Free NEET AI Question Bank: Chapter-wise MCQs with Solutions

BiologyAnatomy of Flowering PlantsDicot and monocot rootsEasy

Q1Which layer of the root has barrel-shaped cells with deposits of waterproof, suberin-rich bands called Casparian strips on the radial and tangential walls?

BiologyAnatomy of Flowering PlantsEpidermis and stomataEasy

Q2Guard cells of the stomata are usually bean-shaped. In which group of plants are they dumb-bell shaped?

BiologyAnatomy of Flowering PlantsHairs and ground tissueMedium

Q3Match each tissue or feature with the plant organ where it is characteristically found.

Column I

Column II

P. Hypodermis of collenchyma

1. Monocot stem

Q. Hypodermis of sclerenchyma

2. Dicot stem

R. Bulliform cells

3. Grass leaf

S. Casparian strips

4. Root endodermis

BiologyAnatomy of Flowering PlantsVascular bundlesMedium

Q4Vascular bundles differ in their structure. Evaluate the two statements.

Statement I: Open vascular bundles have a strip of cambium between xylem and phloem, and they are present in dicot stems.
Statement II: The vascular bundles of a monocot stem are conjoint and closed, and a well-developed phloem parenchyma is present in them.

BiologyAnatomy of Flowering PlantsDicot and monocot rootsMedium

Q5In a transverse section of a root, more than six xylem bundles (polyarch) are seen around a large, well-developed pith. What does this indicate?

BiologyAnatomy of Flowering PlantsDicot and monocot rootsMedium

Q6Lateral roots and, in dicot roots, part of the vascular cambium arise from a tissue just inside the endodermis. Which tissue is this?

BiologyAnatomy of Flowering PlantsMonocot stemMedium

Q7Monocot stems typically do not increase in girth by secondary growth. Evaluate the Assertion and Reason.

Assertion (A): Monocot stems do not show secondary growth.
Reason (R): The vascular bundles of the monocot stem are closed, with no cambium between the xylem and phloem.

BiologyAnatomy of Flowering PlantsEpidermis and stomataHard

Q8Which one of the following statements about the stomatal apparatus of a leaf epidermis is INCORRECT?

BiologyAnatomy of Flowering PlantsIsobilateral leafEasy

Q9Which of the following is a feature of the isobilateral leaf of monocots such as grasses?

BiologyAnatomy of Flowering PlantsDicot stemHard

Q10Which sequence correctly gives the tissues met in a dicot stem, going from the outside inwards up to the vascular bundles?

BiologyAnimal KingdomLevels of organisationEasy

Q11Animals show different grades of body organisation. In which phylum are the cells arranged only at the cellular level, with some division of labour but no true tissues?

BiologyAnimal KingdomCoelom, segmentation and notochordEasy

Q12The body of an earthworm is externally and internally divided into segments with a serial repetition of organs. In which phylum is such metamerism first seen?

BiologyAnimal KingdomFlatworms, roundworms and annelidsMedium

Q13Match each phylum with its excretory structure.

Column I

Column II

P. Platyhelminthes

1. Malpighian tubules

Q. Annelida

2. Flame cells

R. Arthropoda

3. Nephridia

S. Hemichordata

4. Proboscis gland

BiologyAnimal KingdomCoelom, segmentation and notochordMedium

Q14Body cavities and gut completeness vary among worms. Evaluate the two statements.

Statement I: In aschelminthes the body cavity is not lined by mesoderm, so they are pseudocoelomates.
Statement II: Flatworms have a true coelom and a complete digestive tract with both mouth and anus.

BiologyAnimal KingdomEchinoderms and hemichordatesMedium

Q15Which statement correctly describes the symmetry of echinoderms such as starfish?

BiologyAnimal KingdomJawless and jawed fishesMedium

Q16A marine fish has a streamlined body, a ventral mouth, gill slits without an operculum, a tough skin with placoid scales and no air bladder. Males have claspers on the pelvic fins. Which class does it belong to?

BiologyAnimal KingdomSponges, cnidarians and comb jelliesMedium

Q17Sponges are the simplest multicellular animals. Evaluate the Assertion and Reason.

Assertion (A): Sponges show the cellular level of organisation.
Reason (R): In sponges the cells are loosely arranged and show some division of labour, but they are not organised into tissues.

BiologyAnimal KingdomChordates and non-chordatesHard

Q18A rod-like notochord, or a structure resembling it, is found in several animal groups, but its extent and how long it lasts differ from group to group. Which description of it is accurate?

BiologyAnimal KingdomSponges, cnidarians and comb jelliesEasy

Q19Sea walnuts and comb jellies move using eight external rows of ciliated comb plates, and many show bioluminescence. Which phylum are they?

BiologyAnimal KingdomAmphibians and reptilesHard

Q20Which one of the following correctly pairs a vertebrate class with a characteristic of it?

BiologyBiological ClassificationThe five kingdom classificationEasy

Q21Under the five kingdom classification of Whittaker, Chlamydomonas, Chlorella and Paramoecium are all placed in one kingdom. Which kingdom is it?

BiologyBiological ClassificationArchaebacteria, eubacteria and mycoplasmaEasy

Q22Mycoplasma are among the smallest living cells known and can survive without oxygen. Which feature distinguishes them from other bacteria?

BiologyBiological ClassificationKingdom ProtistaMedium

Q23Match each protistan group with its characteristic feature.

Column I

Column II

P. Gonyaulax

1. Rapid multiplication causes red tides

Q. Diatoms

2. Silica walls that leave diatomaceous earth

R. Euglena

3. Flexible protein-rich pellicle

S. Trypanosoma

4. Flagellated parasite causing sleeping sickness

BiologyBiological ClassificationArchaebacteria, eubacteria and mycoplasmaMedium

Q24Blue-green algae are often a source of confusion in classification. Examine the two statements below.

Statement I: Cyanobacteria are placed in Kingdom Protista because they are algae and photosynthetic.
Statement II: Nostoc and Anabaena are filamentous forms that fix atmospheric nitrogen in specialised cells called heterocysts.

BiologyBiological ClassificationKingdom Fungi: body, nutrition and reproductionMedium

Q25In the sexual cycle of some fungi, plasmogamy is not immediately followed by karyogamy. The resulting cell contains two nuclei from the two parents. What is this stage called, and what is its nuclear condition?

BiologyBiological ClassificationThe four classes of fungiMedium

Q26A mushroom such as Agaricus forms four spores borne externally on a club-shaped structure at the tip of a hypha. To which class of fungi does it belong?

BiologyBiological ClassificationThe four classes of fungiHard

Q27Genera are listed with the class of fungi in which NCERT places them. Which pairing is INCORRECT?

BiologyBiological ClassificationViroids, prions and lichensMedium

Q28Viroids are agents of disease in plants. Evaluate the following Assertion and Reason.

Assertion (A): Viroids, the agents of diseases such as potato spindle tuber disease, are smaller than viruses.
Reason (R): A viroid is a free RNA of low molecular weight that lacks the protein coat found in viruses.

BiologyBiological ClassificationViroids, prions and lichensEasy

Q29Lichens are symbiotic associations. Which statement correctly names the partners?

BiologyBiological ClassificationKingdom ProtistaHard

Q30Dinoflagellates and euglenoids are both photosynthetic protists. Which feature do they have in common?

BiologyBiomoleculesLipids, nucleotides and sugarsEasy

Q31Nitrogen bases in nucleic acids are classed as purines or pyrimidines. Which pair contains only purines?

BiologyBiomoleculesLipids, nucleotides and sugarsEasy

Q32Adenosine consists of the nitrogen base adenine linked to a ribose sugar, without a phosphate group. What is it called?

BiologyBiomoleculesClassification of enzymes and co-factorsMedium

Q33Match each class of enzymes with the type of reaction it catalyses.

Column I

Column II

P. Oxidoreductases

1. Hydrolysis of ester, ether, peptide or glycosidic bonds

Q. Transferases

2. Removal of groups from substrates by mechanisms other than hydrolysis, leaving double bonds

R. Hydrolases

3. Transfer of a group other than hydrogen between a pair of substrates

S. Lyases

4. Oxidation-reduction between two substrates

BiologyBiomoleculesFactors affecting enzyme activityMedium

Q34Enzymes and their inhibitors are often misunderstood. Evaluate the two statements.

Statement I: Malonate inhibits succinic dehydrogenase competitively because it closely resembles the substrate succinate in structure.
Statement II: An enzyme speeds up a reaction by changing the energy content of the substrate and of the product, not by lowering the activation energy barrier between them.

BiologyBiomoleculesStructure of proteinsMedium

Q35Adult human haemoglobin consists of four subunits, two α and two β chains, held together. At which level of protein structure is haemoglobin described?

BiologyBiomoleculesPolysaccharidesMedium

Q36A polysaccharide gives a blue colour with iodine because it forms helical secondary structures that hold iodine molecules. Which polysaccharide is this and what can be said about cellulose?

BiologyBiomoleculesFactors affecting enzyme activityMedium

Q37Enzymes respond differently to cold and heat. Evaluate the Assertion and Reason.

Assertion (A): An enzyme kept at a low temperature can usually regain its activity when warmed, but one exposed to a very high temperature loses its activity.
Reason (R): Low temperature only keeps an enzyme in a temporarily inactive state, whereas high temperature denatures its protein structure.

BiologyBiomoleculesClassification of enzymes and co-factorsHard

Q38Which one of the following correctly pairs a co-factor category with an example?

BiologyBiomoleculesProteinsEasy

Q39Different proteins are the most abundant in different contexts. Which is the most abundant protein in the whole biosphere?

BiologyBiomoleculesAmino acidsHard

Q40The R group of an amino acid determines its identity. Which of the following pairs of amino acid and R group is correct?

BiologyBody Fluids and CirculationBlood groupsEasy

Q41Which ABO blood group has neither A nor B antigens on the surface of its red blood cells and is therefore called the universal donor?

BiologyBody Fluids and CirculationThe cardiac cycleEasy

Q42The first heart sound, 'lub', is associated with the closure of which valves?

BiologyBody Fluids and CirculationFormed elements: RBCs, WBCs and plateletsMedium

Q43Match each type of leucocyte with its feature.

Column I

Column II

P. Neutrophils

1. Most numerous WBC, 60-65 per cent

Q. Eosinophils

2. Resist infections; associated with allergic reactions

R. Basophils

3. Secrete histamine, serotonin and heparin

S. Lymphocytes

4. B and T forms responsible for immune responses

BiologyBody Fluids and CirculationElectrocardiogram (ECG)Medium

Q44Examine the following statements about cardiac activity and the ECG.

Statement I: The sino-atrial node (SAN) can generate the maximum number of action potentials per minute and therefore acts as the pacemaker.
Statement II: The QRS complex of an ECG represents the repolarisation of the ventricles.

BiologyBody Fluids and CirculationBlood groupsMedium

Q45In which situation is a baby most likely to suffer from erythroblastosis foetalis?

BiologyBody Fluids and CirculationThe cardiac cycleMedium

Q46A resting person has a heart rate of 80 beats per minute and a stroke volume of 60 mL. What is the cardiac output?

BiologyBody Fluids and CirculationBlood groupsMedium

Q47Blood group AB individuals can receive blood of any ABO group. Evaluate the Assertion and Reason.

Assertion (A): Persons with blood group AB are called universal recipients.
Reason (R): The plasma of group AB persons contains neither anti-A nor anti-B antibodies.

BiologyBody Fluids and CirculationCoagulation of bloodHard

Q48In the clotting cascade, which enzyme converts fibrinogen into fibrin threads, and how is it formed?

BiologyBody Fluids and CirculationRegulation of cardiac activity and disordersEasy

Q49What is the normal blood pressure of a healthy adult, written as systolic over diastolic pressure?

BiologyBody Fluids and CirculationBlood groupsHard

Q50A patient with blood group B Rh-negative needs a transfusion. Considering both ABO and Rh systems, which of the following donors is safe?

BiologyBreathing and Exchange of GasesRespiratory organs — human respiratory systemEasy

Q51Which one of the following correctly gives the sequence of passages through which inhaled air travels, from the external nostrils to the alveoli, in humans?

BiologyBreathing and Exchange of GasesRespiratory organs — larynxEasy

Q52The larynx, commonly called the sound box, lies between the pharynx and the trachea. Which of the following correctly describes a key feature of the larynx and its role during swallowing?

BiologyBreathing and Exchange of GasesMechanism of breathingMedium

Q53During a normal, quiet inspiration in humans, contraction of the diaphragm and the external intercostal muscles brings about a pressure change that draws air into the lungs. Which of the following correctly explains this sequence of events?

BiologyBreathing and Exchange of GasesRespiratory volumes and capacitiesMedium

Q54For an adult, take Tidal Volume (TV) = 500 mL, Inspiratory Reserve Volume (IRV) = 2500 mL and Expiratory Reserve Volume (ERV) = 1000 mL, values within the approximate ranges NCERT gives for a healthy adult. What is the Vital Capacity?

BiologyBreathing and Exchange of GasesExchange of gasesMedium

Q55Efficient gas exchange at the alveoli depends on the properties of the gases themselves as well as on the structure of the membrane they must cross. Evaluate the two statements below on this exchange.

Statement I: The solubility of CO₂ is 20–25 times higher than that of O₂, so the amount of CO₂ that can diffuse through the diffusion membrane per unit difference in partial pressure is much higher than that of O₂.
Statement II: The diffusion membrane is made up of three major layers — the thin squamous epithelium of the alveoli, the endothelium of the alveolar capillaries, and the basement substance in between them — and its total thickness is much less than a millimetre.

BiologyBreathing and Exchange of GasesTransport of gases — oxygenMedium

Q56Read the following two statements about the transport of oxygen in human blood and choose the option that correctly evaluates them.

Statement I: About 97% of the oxygen carried in blood is bound to haemoglobin as oxyhaemoglobin, and each haemoglobin molecule can bind a maximum of four O₂ molecules.
Statement II: A higher partial pressure of CO₂, a higher hydrogen ion concentration, and a higher temperature, as found in the tissues, all favour dissociation of oxygen from oxyhaemoglobin, helping O₂ unload where it is needed.

BiologyBreathing and Exchange of GasesTransport of gases — carbon dioxideHard

Q57Only a small fraction of the CO₂ produced by tissues travels dissolved in plasma. Which of the following correctly describes how most CO₂ is carried in the blood, and which enzyme catalyses the key step of this route?

BiologyBreathing and Exchange of GasesRegulation of respirationHard

Q58Breathing rate is adjusted moment to moment by chemical signals reaching the medulla, not by mechanical stretch alone. Evaluate the following Assertion and Reason on how CO₂ levels drive this regulation.

Assertion (A): A rise in the CO₂ concentration of blood changes the rate and depth of breathing far more strongly than a comparable fall in O₂ concentration.
Reason (R): A chemosensitive area adjacent to the rhythm centre in the medulla, together with receptors associated with the aortic arch and carotid artery, is highly sensitive to CO₂ and H⁺ concentration and signals the rhythm centre to make the necessary adjustments.

BiologyBreathing and Exchange of GasesDisorders of the respiratory systemEasy

Q59Emphysema is a chronic respiratory disorder commonly caused by long-term cigarette smoking. Which of the following correctly describes what happens to the lungs in this disease and its immediate functional consequence?

BiologyBreathing and Exchange of GasesDisorders of the respiratory systemMedium

Q60Workers in industries involving grinding or stone-breaking are exposed over years to excessive dust in their workplace. What kind of respiratory damage does chronic exposure of this sort typically cause, and what is this category of disorders called?

BiologyCell Cycle and Cell DivisionInterphase: G1, S and G2Easy

Q61In the interphase of the cell cycle, during which phase does DNA synthesis and replication take place?

BiologyCell Cycle and Cell DivisionProphase IEasy

Q62Crossing over between non-sister chromatids of homologous chromosomes, at recombination nodules, takes place in which sub-stage of prophase I?

BiologyCell Cycle and Cell DivisionProphase IMedium

Q63Match each sub-stage of prophase I of meiosis with its characteristic event.

Column I

Column II

P. Zygotene

1. Terminalisation of chiasmata

Q. Pachytene

2. X-shaped chiasmata become visible

R. Diplotene

3. Pairing of homologous chromosomes

S. Diakinesis

4. Crossing over at recombination nodules

BiologyCell Cycle and Cell DivisionQuiescent stage and which cells divideMedium

Q64Cells vary in their division behaviour. Evaluate the following statements.

Statement I: In the S phase the DNA content of a cell doubles from 2C to 4C, but the number of chromosomes stays the same.
Statement II: Cells that leave G1 and enter the quiescent stage (G0) become metabolically inactive.

BiologyCell Cycle and Cell DivisionProphase and metaphaseMedium

Q65Cells in the root tip of an onion have 16 chromosomes. How many chromatids are present in one such cell at metaphase of mitosis?

BiologyCell Cycle and Cell DivisionMetaphase I to interkinesisMedium

Q66Meiosis I and meiosis II are separated by a short stage. Which statement describes this stage, called interkinesis, correctly?

BiologyCell Cycle and Cell DivisionSignificance of mitosisMedium

Q67Mitosis is called an equational division. Evaluate the Assertion and Reason.

Assertion (A): Mitosis is described as an equational division.
Reason (R): The number of chromosomes in the daughter cells is the same as that in the parent cell.

BiologyCell Cycle and Cell DivisionMeiosis and its key featuresHard

Q68A diploid cell has DNA content 2C in G1 phase. What is the DNA content of one cell at G2, at the end of meiosis I (each daughter cell) and at the end of meiosis II (each daughter cell) respectively?

BiologyCell Cycle and Cell DivisionCytokinesisEasy

Q69If karyokinesis is not followed by cytokinesis, a multinucleate condition results. What is this condition called, and in which structure is it seen?

BiologyCell Cycle and Cell DivisionAnaphase and telophaseHard

Q70A diploid cell has 2n = 12. During meiosis, how many chromosomes move to each pole in anaphase I and in anaphase II of one of the dividing cells, respectively?

BiologyCell: The Unit of LifeCell TheoryEasy

Q71The cell theory, as it stands today, states that all living organisms are composed of cells and cell products, and that new cells arise only from pre-existing cells. Which scientist added this second part — that cells arise only from pre-existing cells — to Schleiden and Schwann's original formulation?

BiologyCell: The Unit of LifeRibosomesEasy

Q72A prokaryotic ribosome sediments as a 70S particle made of a 50S and a 30S subunit. Free ribosomes lying in the cytoplasm of a eukaryotic cell are larger. What is their sedimentation coefficient and subunit composition?

BiologyCell: The Unit of LifePlasma membraneMedium

Q73The fluid mosaic model of the plasma membrane, proposed by Singer and Nicolson in 1972, describes how membrane lipids and proteins are organised. Which statement correctly describes this arrangement?

BiologyCell: The Unit of LifeEndomembrane system — Golgi apparatusMedium

Q74The Golgi apparatus is an important part of the endomembrane system that packages materials received from the endoplasmic reticulum. Evaluate the two statements below on its structure.

Statement I: The Golgi apparatus consists of many flat, disc-shaped sacs called cisternae, which are stacked parallel to each other and concentrically arranged near the nucleus.
Statement II: The Golgi cisternae have a convex cis face, called the forming face, and a concave trans face, called the maturing face; the two faces are entirely different but interconnected.

BiologyCell: The Unit of LifeMitochondriaMedium

Q75Mitochondria are unusual among cytoplasmic organelles in carrying a genome of their own, in addition to their distinctive double-membrane, cristae-folded architecture. Evaluate the two statements below on mitochondrial structure and genetics.

Statement I: Mitochondria are bound by a double membrane, and the inner membrane is thrown into infoldings called cristae that increase the surface area for ATP synthesis.
Statement II: The mitochondrial matrix contains single circular DNA, a few RNA molecules, ribosomes, and the enzymes required for the synthesis of some of the organelle's own proteins.

BiologyCell: The Unit of LifeEndomembrane system — LysosomesMedium

Q76Lysosomes, popularly nicknamed the 'suicide bags' of the cell because of the powerful digestive enzymes they hold, belong to the endomembrane system. Which statement correctly describes how lysosomes are formed and what they contain?

BiologyCell: The Unit of LifeMitochondria and plastidsHard

Q77Mitochondria and chloroplasts are unlike most other organelles in retaining a trace of genetic independence from the nucleus. Evaluate the following Assertion and Reason on why they are termed semi-autonomous.

Assertion (A): Mitochondria and plastids are described as semi-autonomous organelles.
Reason (R): Both organelles possess their own double-stranded circular DNA, 70S ribosomes, and the machinery to synthesise some of their own proteins, but still depend on nuclear genes for many other proteins.

BiologyCell: The Unit of LifeCell wallMedium

Q78In a mature plant cell that has formed a secondary wall, the wall region between the cell and its neighbour shows three distinct layers. Which of the following correctly lists these layers from outermost to innermost?

BiologyCell: The Unit of LifeCilia and flagellaHard

Q79A transverse section through the shaft of a cilium or flagellum, viewed under the electron microscope, shows a characteristic microtubule arrangement called the axoneme. Which of the following correctly describes this arrangement and the structure that anchors it in the cell?

BiologyCell: The Unit of LifeNucleusEasy

Q80Robert Brown first described the nucleus as a cell organelle in 1831. Inside the nucleoplasm, one or more dense, spherical structures are seen, and they are sites of active ribosomal RNA synthesis. What are these structures called, and are they bound by a membrane?

ChemistryChemical Bonding and Molecular StructureHybridisationEasy

Q81In ethyne (HC≡CH), what is the hybridisation of each carbon atom, and how many sigma (σ) bonds does each carbon form?

ChemistryChemical Bonding and Molecular StructureVSEPR theoryEasy

Q82Sulfur hexafluoride (SF₆) has 6 S–F bond pairs and no lone pair on the central sulfur atom. What molecular shape does VSEPR theory predict for it?

ChemistryChemical Bonding and Molecular StructureHydrogen bondingEasy

Q83Between hydrogen fluoride (HF) and hydrogen chloride (HCl), which molecule(s) show intermolecular hydrogen bonding?

ChemistryChemical Bonding and Molecular StructureMolecular orbital theory / bond orderMedium

Q84Using molecular orbital theory, what is the bond order of the nitrogen molecule (N₂), and is N₂ paramagnetic or diamagnetic?

ChemistryChemical Bonding and Molecular StructureDipole momentMedium

Q85Boron trifluoride (BF₃) contains three polar B–F bonds, yet its measured net dipole moment is zero. What is the correct explanation?

ChemistryChemical Bonding and Molecular StructureHybridisation and VSEPR (expanded octet)Medium

Q86What is the hybridisation of sulfur and the molecular shape of SF₄?

ChemistryChemical Bonding and Molecular StructureHybridisation and molecular shapeMedium

Q87The Assertion (A) and Reason (R) below concern the shape of a xenon fluoride. Read them and choose the option that correctly describes their relationship.

Assertion (A): Xenon tetrafluoride (XeF₄) has a square planar molecular shape.
Reason (R): The Xe atom in XeF₄ is sp³d² hybridised, and its two lone pairs occupy the axial positions of the octahedral electron-pair geometry, leaving the four F atoms and Xe in one plane.

ChemistryChemical Bonding and Molecular StructureMolecular orbital theory / bond order trendsHard

Q88Two statements about the bond orders of O₂, O₂⁺ (dioxygenyl cation), and O₂⁻ (superoxide ion) are given below. Study them and choose the correct option.

Statement I: The bond order of O₂⁺ is higher than the bond order of O₂.
Statement II: The bond order of O₂⁻ is lower than the bond order of O₂.

ChemistryChemical Bonding and Molecular StructureVSEPR theory (expanded octet)Hard

Q89Chlorine trifluoride (ClF₃) has 3 Cl–F bond pairs and 2 lone pairs on the central chlorine atom. What molecular shape does VSEPR theory predict?

BiologyChemical Coordination and IntegrationThe pituitary glandEasy

Q90Where are the hormones oxytocin and vasopressin (ADH) actually synthesised, before being stored and released by the posterior pituitary?

BiologyChemical Coordination and IntegrationPineal and thyroid glandsEasy

Q91Deficiency of iodine in the diet causes enlargement of the thyroid gland. What is this condition called?

BiologyChemical Coordination and IntegrationThe pituitary glandMedium

Q92Match each disorder with its hormonal cause.

Column I

Column II

P. Acromegaly

1. Excess growth hormone in adults

Q. Diabetes insipidus

2. Impaired ADH function

R. Pituitary dwarfism

3. Deficiency of growth hormone in childhood

S. Cretinism

4. Thyroid hormone deficiency during pregnancy

BiologyChemical Coordination and IntegrationPancreasMedium

Q93Evaluate the following statements about the endocrine pancreas.

Statement I: Glucagon, secreted by the α-cells of the islets of Langerhans, acts mainly on hepatocytes and stimulates glycogenolysis, causing hyperglycemia.
Statement II: Insulin, secreted by the β-cells, is a hyperglycemic hormone because it increases the release of glucose from the liver.

BiologyChemical Coordination and IntegrationParathyroid gland and thymusMedium

Q94Which hormone acts on bones to stimulate bone resorption and increases Ca²⁺ absorption by renal tubules and from digested food, thereby increasing blood calcium?

BiologyChemical Coordination and IntegrationAdrenal glandMedium

Q95Which of the following correctly matches a zone or region of the adrenal gland with the main type of hormone it secretes?

BiologyChemical Coordination and IntegrationMechanism of hormone actionHard

Q96Hormones act through receptors located in different places. Evaluate the Assertion and Reason.

Assertion (A): Steroid hormones such as cortisol usually act through intracellular receptors and regulate gene expression.
Reason (R): Steroid hormones are lipid-soluble, so they can cross the cell membrane to reach the intracellular receptors, whereas protein hormones bind to membrane-bound receptors.

BiologyChemical Coordination and IntegrationTestis and ovaryHard

Q97Which of the following correctly pairs a hormone with the cells or structure that mainly secrete it?

BiologyChemical Coordination and IntegrationHormones of heart, kidney and gutEasy

Q98Atrial natriuretic factor (ANF) is secreted by the atrial wall of the heart. What is its effect on blood pressure?

BiologyChemical Coordination and IntegrationThe pituitary glandMedium

Q99Which hormone is secreted only by the pars intermedia of the pituitary gland?

ChemistryClassification of Elements and Periodicity in PropertiesNomenclature of elements with Z > 100Easy

Q100Before an element receives its official name, IUPAC gives it a systematic name built from the digits of its atomic number. What is the systematic name of the element with Z = 109?

ChemistryClassification of Elements and Periodicity in PropertiesElectronic configuration and position in the tableEasy

Q101An element has the ground-state configuration [Ar]3d¹⁰4s²4p³. Where does it sit in the long form of the periodic table?

ChemistryClassification of Elements and Periodicity in PropertiesIonic radiusEasy

Q102N³⁻, O²⁻, Na⁺ and Mg²⁺ each have 10 electrons. Which order of ionic radius is correct?

ChemistryClassification of Elements and Periodicity in PropertiesIonization enthalpyMedium

Q103Which is the correct order of first ionization enthalpy for boron, carbon, nitrogen and oxygen?

ChemistryClassification of Elements and Periodicity in PropertiesElectron gain enthalpyMedium

Q104Arrange F, Cl, Br and I in order of decreasing magnitude of electron gain enthalpy (most negative first).

ChemistryClassification of Elements and Periodicity in PropertiesIonization enthalpyMedium

Q105Magnesium and aluminium sit next to each other in period 3. Judge the Assertion (A) and the Reason (R) below.

Assertion (A): The first ionization enthalpy of magnesium is higher than that of aluminium.
Reason (R): The electron removed from aluminium is a 3p electron, which is shielded by the 3s electrons and lies higher in energy than a 3s electron.

ChemistryClassification of Elements and Periodicity in PropertiesAnomalous properties of second period elementsMedium

Q106Lithium, beryllium and boron often behave differently from the heavier members of their groups. Which of the statements below are correct?

Statement I: The maximum covalency of a second-period element is 4, because it has only four valence orbitals.
Statement II: Boron forms the ion [BF₆]³⁻ just as aluminium forms [AlF₆]³⁻.
Statement III: Lithium shows several similarities to magnesium, an example of a diagonal relationship.
Statement IV: Sodium oxide, Na₂O, is amphoteric.

ChemistryClassification of Elements and Periodicity in PropertiesPeriodic trends and chemical reactivityMedium

Q107Oxides change character across the periodic table. Match each oxide in List I with its acid–base nature in List II.

Column I

Column II

P. Na₂O

1. Amphoteric

Q. Cl₂O₇

2. Neutral

R. As₂O₃

3. Basic

S. N₂O

4. Acidic

ChemistryClassification of Elements and Periodicity in PropertiesIonization enthalpyHard

Q108The first four ionization enthalpies of a main-group element M are 578, 1817, 2745 and 11 577 kJ mol⁻¹. What is the most likely formula of its oxide?

ChemistryClassification of Elements and Periodicity in PropertiesIonization enthalpyHard

Q109Which order of first ionization enthalpy is correct for sodium, magnesium, aluminium and silicon?

ChemistryEquilibriumRelationship between Kp and KcEasy

Q110For the gas-phase equilibrium 2SO₃(g) ⇌ 2SO₂(g) + O₂(g), which relation between Kp and Kc is correct?

ChemistryEquilibriumFactors affecting equilibria: Le Chatelier's principleEasy

Q111For the equilibrium N₂O₄(g) ⇌ 2NO₂(g), ΔH > 0, which change increases the amount of NO₂ present at the new equilibrium?

ChemistryEquilibriumCalculating equilibrium constantsMedium

Q1122.0 mol of A(g) and 2.0 mol of B(g) are placed in a sealed 2.0 L flask at a fixed temperature. The reaction A(g) + B(g) ⇌ 2C(g) reaches equilibrium when 1.6 mol of C is present. What is Kc?

ChemistryEquilibriumIonization constants of weak acidsMedium

Q113What is the pH of a 0.020 M aqueous solution of a weak monobasic acid HA whose Ka = 2.0 × 10⁻⁵ at 298 K? (log 2 = 0.301, log 6.32 = 0.80)

ChemistryEquilibriumCommon ion effect in ionization of acidsMedium

Q114Read the Assertion (A) and Reason (R) and choose the correct option.

Assertion (A): Dissolving solid sodium acetate in an aqueous solution of acetic acid raises the pH of the solution.
Reason (R): The added acetate ions shift the equilibrium CH₃COOH ⇌ CH₃COO⁻ + H⁺ to the left, lowering [H⁺].

ChemistryEquilibriumSolubility product constantMedium

Q115A sparingly soluble salt M₂X dissociates as M₂X(s) ⇌ 2M⁺(aq) + X²⁻(aq). Its solubility product at 298 K is 3.2 × 10⁻¹¹. What is its molar solubility in pure water?

ChemistryEquilibriumThe pH scale: strong basesEasy

Q116What is the pH of a 0.005 M aqueous solution of Ba(OH)₂ at 298 K? Assume complete dissociation. (Kw = 1.0 × 10⁻¹⁴, log 2 = 0.301)

ChemistryEquilibriumBuffer solutionsHard

Q11760 mL of 0.10 M aqueous NH₃ is mixed with 20 mL of 0.10 M HCl at 298 K. What is the pH of the resulting solution? (pKb of NH₃ = 4.75, log 2 = 0.301, log 3 = 0.477, Kw = 1.0 × 10⁻¹⁴)

ChemistryEquilibriumRelationship between equilibrium constant K and ΔG°Hard

Q118For a reaction at 300 K, ΔG° = +5.74 kJ mol⁻¹. What is the value of the equilibrium constant K at this temperature? (R = 8.314 J K⁻¹ mol⁻¹; e^(−2.30) ≈ 0.10)

BiologyExcretory Products and Their EliminationNitrogenous wastesEasy

Q119Among the nitrogenous wastes ammonia, urea and uric acid, which is the most toxic and requires the largest amount of water for its elimination?

BiologyExcretory Products and Their EliminationGlomerular filtrationEasy

Q120What is the approximate glomerular filtration rate (GFR) in a healthy human?

BiologyExcretory Products and Their EliminationExcretory structures in animalsMedium

Q121Excretory organs differ across animal groups. Pair each animal in the left list with the organ that removes its wastes.

Column I

Column II

P. Planaria

1. Protonephridia (flame cells)

Q. Earthworm

2. Nephridia

R. Cockroach

3. Malpighian tubules

S. Prawn

4. Antennal or green glands

BiologyExcretory Products and Their EliminationFunction of the tubulesMedium

Q122The loop of Henle has two limbs with different permeabilities. Evaluate the statements.

Statement I: The descending limb of the loop of Henle is permeable to water but almost impermeable to electrolytes.
Statement II: The ascending limb is permeable to water and impermeable to electrolytes.

BiologyExcretory Products and Their EliminationRegulation of kidney functionMedium

Q123Excessive loss of body fluid, for example during heavy sweating, activates the osmoreceptors. Which hormone is released from the neurohypophysis as a result?

BiologyExcretory Products and Their EliminationRegulation of kidney functionMedium

Q124A fall in glomerular blood pressure activates the renin-angiotensin mechanism. Which hormone then acts on the distal parts of the tubule to cause reabsorption of Na⁺ and water?

BiologyExcretory Products and Their EliminationCounter current mechanismMedium

Q125Human kidneys can produce urine about four times as concentrated as the initial filtrate. Evaluate the Assertion and Reason.

Assertion (A): Human kidneys can produce urine that is about four times more concentrated than the glomerular filtrate.
Reason (R): The counter current arrangement of the loop of Henle and vasa recta maintains an osmolarity gradient in the medullary interstitium, from about 300 mOsmol L⁻¹ in the cortex to about 1200 mOsmol L⁻¹ in the inner medulla.

BiologyExcretory Products and Their EliminationReabsorption and secretionHard

Q126A healthy adult has a GFR of 125 mL per minute and passes about 1.5 litres of urine a day. Roughly what percentage of the glomerular filtrate is reabsorbed?

BiologyExcretory Products and Their EliminationThe nephronEasy

Q127Which of the following parts of the nephron are all located in the renal cortex?

BiologyExcretory Products and Their EliminationRole of other organs in excretionHard

Q128Besides the kidneys, other organs help in excretion. Which of the following pairings of an organ and the substance it eliminates is correct?

PhysicsGravitationKepler's lawsEasy

Q129A planet moves round a star in an elliptical orbit. Its closest distance from the star is 1.0 × 10¹¹ m, where its speed is 30 km s⁻¹, and its farthest distance is 1.5 × 10¹¹ m. Its speed at the farthest point is

PhysicsGravitationg above and below the surfaceEasy

Q130A body weighs 72 N on the earth's surface. What would it weigh at a height above the surface equal to the earth's radius?

PhysicsGravitationEscape speedEasy

Q131Consider statements I to IV about the escape speed from the surface of a planet (atmosphere ignored). Select the option that names every correct statement and no incorrect one.

I. The escape speed does not depend on the mass of the body being launched.
II. The escape speed from the moon's surface is less than that from the earth's surface.
III. The escape speed from a planet's surface is √2 times the speed of a satellite orbiting just above that surface.
IV. The escape speed from the earth's surface is about 7.9 km s⁻¹.

PhysicsGravitationg above and below the surfaceMedium

Q132At a height of 32 km above the earth's surface the acceleration due to gravity has some value g′. Treating the earth as a uniform sphere and using the small-height approximation, at what depth below the surface does g have the same value g′?

PhysicsGravitationEnergy of an orbiting satelliteHard

Q133A satellite of mass m orbits the earth (mass M, radius R) in a circular orbit of radius 2R. How much energy must be supplied to shift it to a circular orbit of radius 3R?

PhysicsGravitationEarth satellitesMedium

Q134Satellite P circles a planet with period 8 h at orbital radius r. Satellite Q circles the same planet at radius 4r. The period of Q is

PhysicsGravitationEscape speedMedium

Q135A planet has the same mean density as the earth but twice its radius. If the escape speed from the earth's surface is 11.2 km s⁻¹, the escape speed from this planet's surface is

PhysicsGravitationEnergy of an orbiting satelliteMedium

Q136Why is a satellite bound to the earth? Weigh the Assertion (A) on the sign of its total mechanical energy against the Reason (R) comparing its kinetic and potential energies.

Assertion (A): The total mechanical energy of a satellite in a circular orbit round the earth is negative.
Reason (R): The gravitational potential energy of the satellite is negative and its magnitude is greater than the satellite's kinetic energy.

PhysicsGravitationEarth satellitesMedium

Q137A satellite of mass m moves in a circular orbit of radius r round a planet of mass M. Match each quantity in List I with its expression in List II.

Column I

Column II

P. Orbital speed

1. −GMm/2r

Q. Kinetic energy

2. √(GM/r)

R. Potential energy

3. −GMm/r

S. Total energy

4. GMm/2r

PhysicsGravitationg above and below the surfaceHard

Q138At what height above the earth's surface does the acceleration due to gravity fall to 64% of its value at the surface? Take the earth's radius as 6400 km.

ChemistryHydrocarbonsAddition of hydrogen halides to alkenesEasy

Q139Propene reacts with HBr in the dark and with no peroxide present. What is the major product?

ChemistryHydrocarbonsAcidic character of alkynesEasy

Q140Which hydrocarbon reacts with sodium metal to liberate hydrogen gas and form a sodium salt?

ChemistryHydrocarbonsConformations of ethaneEasy

Q141Which statement about the conformations of ethane is correct?

ChemistryHydrocarbonsOzonolysis of alkenesMedium

Q142An alkene C₅H₁₀ on ozonolysis (O₃, then Zn/H₂O) gives propanone and ethanal. What is the alkene?

ChemistryHydrocarbonsPeroxide effectMedium

Q143Propene is treated with HCl in the presence of benzoyl peroxide. Judge the Assertion (A) and the Reason (R) below.

Assertion (A): The product is 2-chloropropane, the Markovnikov product, even though peroxide is present.
Reason (R): The H–Cl bond is too strong to be split by the free radicals formed from the peroxide, so no radical chain starts.

ChemistryHydrocarbonsPreparation of alkanesMedium

Q144A concentrated aqueous solution of sodium propanoate is electrolysed. Which alkane is formed at the anode?

ChemistryHydrocarbonsBenzene structure and aromaticityMedium

Q145Benzene was once drawn with alternating single and double bonds. Which of the statements below about its structure and aromaticity are correct?

Statement I: Benzene is a planar molecule in which every carbon atom is sp² hybridised.
Statement II: Cyclooctatetraene is aromatic because it is cyclic and fully conjugated.
Statement III: All six carbon–carbon bonds in benzene have the same length, 139 pm.
Statement IV: Benzene readily undergoes addition reactions in preference to substitution.

ChemistryHydrocarbonsDirective influence of functional groupsMedium

Q146A substituent already on a benzene ring decides where the next electrophile goes and how fast. Match each substituent in List I with its behaviour in List II.

Column I

Column II

P. –CH₃

1. ortho/para-directing, deactivating

Q. –NO₂

2. meta-directing, deactivating

R. –Cl

3. ortho/para-directing, strongly activating by resonance

S. –OH

4. ortho/para-directing, activating by +I effect and hyperconjugation

ChemistryHydrocarbonsElectrophilic substitution in benzeneHard

Q147Starting from benzene, which sequence gives 1-bromo-3-nitrobenzene (m-bromonitrobenzene) as the major product?

ChemistryHydrocarbonsPreparation of alkenes from alkynesHard

Q148Pent-2-yne is reduced in two separate experiments: (i) with H₂ over Lindlar's catalyst to give X, and (ii) with sodium in liquid ammonia to give Y. Which statement is correct?

PhysicsKinetic TheoryKinetic interpretation of temperatureEasy

Q149The average translational kinetic energy of a molecule of an ideal gas at 300 K is (k_B = 1.38 × 10⁻²³ J K⁻¹)

PhysicsKinetic TheoryKinetic interpretation of temperatureEasy

Q150A sealed flask holds a mixture of hydrogen (H₂) and oxygen (O₂) gases in thermal equilibrium. How do the average translational kinetic energies of their molecules compare?

PhysicsKinetic TheoryPressure of an ideal gas from molecular impactsEasy

Q151A bicycle pump's outlet is blocked and its piston is pushed in slowly, so the trapped air stays at room temperature. Evaluate the Assertion (A) about the air's pressure and the molecular Reason (R) offered for it.

Assertion (A): When the trapped air is compressed at constant temperature, its pressure increases.
Reason (R): The number of molecules per unit volume increases, so molecules strike each unit area of the walls more often.

PhysicsKinetic TheoryKinetic interpretation of temperatureMedium

Q152At what temperature will hydrogen molecules (molar mass 2 g mol⁻¹) have the same rms speed as oxygen molecules (molar mass 32 g mol⁻¹) have at 27 °C?

PhysicsKinetic TheoryKinetic interpretation of temperatureMedium

Q153Find the rms speed of helium atoms (molar mass 4.0 g mol⁻¹) at 127 °C. Take R = 8.31 J mol⁻¹ K⁻¹.

PhysicsKinetic TheorySpecific heats of gasesHard

Q154One mole of a monatomic ideal gas is mixed with one mole of a rigid diatomic ideal gas. The ratio of specific heats γ = C_p/C_v of the mixture is

PhysicsKinetic TheoryDalton's law of partial pressuresMedium

Q155A 20.0 L vessel at 300 K contains 0.50 mol of O₂ and 1.50 mol of N₂, which do not react. Take R = 8.31 J mol⁻¹ K⁻¹. The partial pressure of oxygen is about

PhysicsKinetic TheoryDegrees of freedom and equipartitionMedium

Q156Using the law of equipartition of energy, match each substance in List I with its molar specific heat at constant volume in List II.

Column I

Column II

P. Monatomic gas

1. 3R

Q. Rigid diatomic gas

2. 7R/2

R. Diatomic gas with one vibrational mode

3. 3R/2

S. Solid (equipartition)

4. 5R/2

PhysicsKinetic TheoryMean free pathMedium

Q157Gas molecules move fast, yet a smell spreads slowly across a room because each molecule travels only a short distance between collisions. Which of the claims I to IV about this mean free path are correct?

I. At a fixed temperature, doubling the pressure of the gas halves the mean free path.
II. The mean free path is directly proportional to the square of the molecular diameter.
III. At a fixed pressure, raising the temperature increases the mean free path.
IV. The mean free path increases when the number of molecules per unit volume increases.

PhysicsKinetic TheoryPressure of an ideal gas from molecular impactsHard

Q158Oxygen gas fills a 2.0 L container at a pressure of 1.5 × 10⁵ Pa. Treating it as an ideal gas, the total translational kinetic energy of all its molecules is

PhysicsLaws of MotionImpulseEasy

Q159A 0.40 kg football moving horizontally at 12 m/s strikes a vertical wall head-on and rebounds along the same line at 8 m/s. The ball is in contact with the wall for 0.05 s. What is the magnitude of the average force exerted by the wall on the ball?

PhysicsLaws of MotionNewton's second law of motionEasy

Q160A 5.0 kg block rests on a frictionless horizontal floor. It is pulled by a rope with a constant force of 20 N directed at 37° above the horizontal. The block stays in contact with the floor. Take sin 37° = 0.6 and cos 37° = 0.8. What is the acceleration of the block?

PhysicsLaws of MotionNewton's third law of motionEasy

Q161Four claims about action-reaction force pairs (Newton's third law) are listed below as I to IV. Select the option that names every correct claim and no incorrect one.

I. The action and reaction forces of a pair always act on two different bodies.
II. Action and reaction cancel each other, so the net force on any body is always zero.
III. For a book resting on a table, the book's weight and the normal force from the table on the book form an action-reaction pair.
IV. Action and reaction are equal in magnitude even when the interacting bodies are accelerating.

PhysicsLaws of MotionSolving problems in mechanics (connected bodies)Medium

Q162Two blocks of masses 5 kg and 3 kg hang at the two ends of a light inextensible string that passes over a light frictionless pulley fixed to the ceiling. The system is released from rest. Take g = 10 m s⁻². What is the tension in the string while the blocks move?

PhysicsLaws of MotionFrictionMedium

Q163A 4 kg crate rests on a horizontal floor. The coefficient of static friction between the crate and the floor is 0.5 and the coefficient of kinetic friction is 0.4. A worker pushes the crate with a horizontal force of 18 N. Take g = 10 m s⁻². What is the frictional force acting on the crate?

PhysicsLaws of MotionApparent weight (Newton's second law)Medium

Q164A 60 kg student stands on a bathroom scale placed on the floor of a lift. The lift is moving upward but slowing down at a steady rate of 2.5 m s⁻². Take g = 10 m s⁻². What force does the scale show?

PhysicsLaws of MotionCircular motion (car on a level road)Medium

Q165A car takes an unbanked, level circular turn of radius 50 m. The coefficient of static friction between the tyres and the road is 0.45. Take g = 10 m s⁻². What is the maximum speed at which the car can take the turn without skidding?

PhysicsLaws of MotionSolving problems in mechanics (friction with connected bodies)Hard

Q166A 4 kg block rests on a rough horizontal table. A light inextensible string tied to it runs horizontally to a light frictionless pulley at the table's edge and then hangs vertically, carrying a 2 kg block. The coefficient of kinetic friction between the 4 kg block and the table is 0.25. The system is released and the blocks slide. Take g = 10 m s⁻². What is the tension in the string?

PhysicsLaws of MotionConservation of momentumHard

Q167A 60 kg skater stands at rest on frictionless ice holding a 3 kg ball. She throws the ball horizontally forward so that, just after release, the ball moves at 12 m/s relative to her. What is the skater's recoil speed relative to the ice?

BiologyLocomotion and MovementAxial skeletonEasy

Q168How many bones are present in the skeleton of an adult human?

BiologyLocomotion and MovementTypes of muscleEasy

Q169Which type of muscle is striated in appearance, branched, and involuntary in action?

BiologyLocomotion and MovementJointsMedium

Q170Match each type of synovial joint with an example.

Column I

Column II

P. Ball and socket

1. Between humerus and pectoral girdle

Q. Hinge

2. Knee joint

R. Pivot

3. Between atlas and axis

S. Gliding

4. Between the carpals

BiologyLocomotion and MovementMechanism of muscle contractionMedium

Q171Examine the statements about muscle contraction.

Statement I: During contraction of a sarcomere, the I band and the H zone become narrower, while the length of the A band remains the same.
Statement II: Ca²⁺ ions released from the sarcoplasmic reticulum bind to tropomyosin and thereby expose the active sites on actin.

BiologyLocomotion and MovementAxial skeletonMedium

Q172Humans have 12 pairs of ribs. Which statement correctly describes the last two pairs, called floating ribs?

BiologyLocomotion and MovementMechanism of muscle contractionMedium

Q173During muscle contraction, Ca²⁺ ions bind to a subunit of troponin on the thin filament. What happens immediately after this?

BiologyLocomotion and MovementRed and white fibresMedium

Q174Muscle fibres are classified as red or white. Evaluate the Assertion and Reason.

Assertion (A): Red muscle fibres depend mainly on aerobic respiration for energy.
Reason (R): Red fibres have a high amount of myoglobin and plenty of mitochondria, and they utilise large amounts of oxygen.

BiologyLocomotion and MovementAxial skeletonHard

Q175The 80 bones of the human axial skeleton are grouped by NCERT into the skull, vertebral column (26 bones), sternum (1) and ribs (12 pairs). The skull itself includes 8 cranial bones and 14 facial bones, along with some other bones. How many bones of the skull are neither cranial nor facial?

BiologyLocomotion and MovementJointsEasy

Q176The bones of the skull are joined to each other by sutures. To which type of joint do these belong?

BiologyLocomotion and MovementStructure of contractile proteinsHard

Q177Four descriptions of the protein filaments of a sarcomere are given below. Which description is accurate?

PhysicsMechanical Properties of FluidsAtmospheric and gauge pressureEasy

Q178A diver descends in a freshwater lake (density 1000 kg m⁻³). Atmospheric pressure at the surface is 1.0 × 10⁵ Pa; take g = 10 m s⁻². At what depth is the absolute pressure on the diver twice the atmospheric pressure?

PhysicsMechanical Properties of FluidsHydraulic machinesEasy

Q179In a hydraulic lift the small piston has area 10 cm² and the large piston has area 500 cm². What force on the small piston will just support a car of weight 15 000 N on the large piston (pistons at the same level, friction negligible)?

PhysicsMechanical Properties of FluidsAngle of contact, drops and bubblesEasy

Q180A soap bubble and a liquid drop of equal radius are made from the same soap solution. Decide whether the Assertion (A) about their excess pressures is true, and whether the Reason (R) accounts for it.

Assertion (A): The excess pressure inside a soap bubble is twice the excess pressure inside a liquid drop of the same radius, made from the same solution.
Reason (R): A soap bubble film has two surfaces in contact with air, while a liquid drop has only one.

PhysicsMechanical Properties of FluidsBernoulli's principleMedium

Q181Water flows steadily through a horizontal pipe that narrows from a cross-section of 20 cm² to 5 cm². The speed in the wide part is 1.0 m s⁻¹. Taking the density of water as 1000 kg m⁻³, the pressure in the wide part exceeds that in the narrow part by

PhysicsMechanical Properties of FluidsBernoulli's principleMedium

Q182An open tank stands on level ground. A small hole in its side is 1.8 m above the ground and 0.80 m below the water surface. Take g = 10 m s⁻² and treat the water surface as nearly stationary. How far from the base of the tank does the jet first strike the ground?

PhysicsMechanical Properties of FluidsViscosity and Stokes' lawMedium

Q183A steel ball of radius 1.0 mm falling through glycerine reaches a terminal speed of 2.0 cm s⁻¹. What terminal speed will a ball of the same steel, of radius 3.0 mm, reach in the same glycerine (Stokes' law assumed to hold)?

PhysicsMechanical Properties of FluidsCapillary riseMedium

Q184A clean glass capillary of internal diameter 0.40 mm is dipped vertically in water. Surface tension of water = 0.072 N m⁻¹, angle of contact = 0°, density = 1000 kg m⁻³, g = 10 m s⁻². How high does the water rise in the tube?

PhysicsMechanical Properties of FluidsViscosity and Stokes' lawMedium

Q185Honey, air and glycerine all resist flow. Which of the claims I to IV about viscosity, its temperature dependence and Stokes' drag are correct?

I. The viscosity of a liquid decreases as its temperature rises.
II. The viscosity of a gas increases as its temperature rises.
III. The SI unit of the coefficient of viscosity is the pascal second (Pa s).
IV. In Stokes' law, the viscous drag on a sphere is proportional to the square of its speed.

PhysicsMechanical Properties of FluidsDynamic liftHard

Q186Air flows past the wing of a small aircraft at 70 m s⁻¹ over the upper surface and 60 m s⁻¹ under the lower surface. The wing area is 30 m² and the density of air is 1.2 kg m⁻³. Treating the wing as thin, the upward lift on the wing is about

PhysicsMechanical Properties of FluidsAngle of contact, drops and bubblesHard

Q187A tiny air bubble of radius 0.10 mm is 0.50 m below the surface of water. Take atmospheric pressure = 1.00 × 10⁵ Pa, density of water = 1000 kg m⁻³, g = 10 m s⁻² and surface tension of water = 0.072 N m⁻¹. The pressure of the air inside the bubble is

PhysicsMechanical Properties of SolidsYoung's modulusEasy

Q188A wire 2.0 m long with cross-sectional area 1.0 mm² stretches by 1.0 mm when a force of 100 N is applied along its length. Young's modulus of the material is

PhysicsMechanical Properties of SolidsYoung's modulusEasy

Q189Rubber stretches far more than steel under the same load, yet physics calls steel the more elastic material. Judge the Assertion (A) and Reason (R) on this point.

Assertion (A): Steel is more elastic than rubber.
Reason (R): For the same stress, steel shows a much smaller strain than rubber, so its Young's modulus is much larger.

PhysicsMechanical Properties of SolidsBulk modulus and compressibilityEasy

Q190Which elastic modulus can be defined for a liquid?

PhysicsMechanical Properties of SolidsYoung's modulusMedium

Q191Wires A and B are made of the same steel. B is twice as long as A and has twice the radius. When the same load hangs from each, the ratio of extensions ΔL_A : ΔL_B is

PhysicsMechanical Properties of SolidsBulk modulus and compressibilityMedium

Q192The bulk modulus of water is 2.2 × 10⁹ N m⁻². By what fraction does the volume of a water sample decrease when the pressure on it is increased by 1.1 × 10⁷ N m⁻²?

PhysicsMechanical Properties of SolidsPoisson's ratio and elastic energyMedium

Q193A steel wire (Y = 2.0 × 10¹¹ N m⁻²) is under a tensile stress of 2.0 × 10⁸ N m⁻², within its elastic limit. The elastic potential energy stored per unit volume of the wire is

PhysicsMechanical Properties of SolidsHooke's law and the stress-strain curveMedium

Q194A metal wire is loaded steadily until it breaks. Match each feature of its stress-strain curve in List I with its description in List II.

Column I

Column II

P. Proportional limit

1. Strain that remains after the load is removed from beyond the yield point

Q. Yield point (elastic limit)

2. Largest stress up to which stress is proportional to strain

R. Permanent set

3. Stress beyond which the wire does not regain its original length on unloading

S. Fracture point

4. Stress at which the wire breaks

PhysicsMechanical Properties of SolidsShear modulusMedium

Q195Young's, shear and bulk moduli and Poisson's ratio describe how a solid deforms. Pick the option listing exactly the true claims among I to IV on their signs, sizes and dimensions.

I. Poisson's ratio has neither unit nor dimensions.
II. For most materials the shear modulus is about one-third of Young's modulus.
III. The bulk modulus of a material is negative because its volume decreases when pressure increases.
IV. Stress has the same dimensional formula as pressure.

PhysicsMechanical Properties of SolidsShear modulusHard

Q196A metal cube of side 10 cm is fixed at its base. A tangential force of 5.0 × 10⁴ N acts on its top face. The shear modulus of the metal is 2.5 × 10¹⁰ N m⁻². By how much is the top face displaced relative to the bottom?

PhysicsMechanical Properties of SolidsPoisson's ratio and elastic energyHard

Q197A wire 2.0 m long and 1.0 mm in diameter is stretched by 1.0 mm. The Poisson's ratio of its material is 0.30. The decrease in its diameter is

BiologyMorphology of Flowering PlantsRoot systems and the root tipEasy

Q198The root tip of a flowering plant has four regions. In which region do root hairs form, increasing the surface area for absorption of water and minerals?

BiologyMorphology of Flowering PlantsCompound leaves and phyllotaxyEasy

Q199In a palmately compound leaf the leaflets are attached at a common point at the tip of the petiole. Which of the following plants has such leaves?

BiologyMorphology of Flowering PlantsGynoecium and placentationHard

Q200Match each type of placentation with a plant that shows it.

Column I

Column II

P. Marginal

1. Sunflower

Q. Axile

2. Mustard

R. Parietal

3. Lemon

S. Basal

4. Pea

BiologyMorphology of Flowering PlantsRacemose and cymose inflorescenceMedium

Q201Flowers on an inflorescence axis may open in different orders. Evaluate the following statements.

Statement I: In a racemose inflorescence the main axis continues to grow, and the flowers are borne in acropetal succession, with younger flowers towards the tip.
Statement II: In a cymose inflorescence the main axis terminates in a flower, and the flowers are borne in acropetal order.

BiologyMorphology of Flowering PlantsOvary position on the thalamusMedium

Q202In flowers of plum, rose and peach, the gynoecium is situated in the centre and the other floral parts are located on the rim of the thalamus almost at the same level as it. How are the ovary and the flower described?

BiologyMorphology of Flowering PlantsCalyx, corolla and aestivationMedium

Q203The petals in the flower buds of Cassia and gulmohur overlap one another at the margins but not in any definite direction. This type of aestivation is called

BiologyMorphology of Flowering PlantsAndroeciumMedium

Q204Stamens may be attached to different floral parts. Evaluate the Assertion and Reason.

Assertion (A): The stamens of lily are described as epiphyllous.
Reason (R): In lily the calyx and corolla are not distinct and together form a perianth, and the stamens are attached to this perianth.

BiologyMorphology of Flowering PlantsFruit and seedMedium

Q205A mango develops from a monocarpellary, superior, one-seeded ovary. Its pericarp has a fleshy edible mesocarp and a stony hard endocarp. Which type of fruit is it?

BiologyMorphology of Flowering PlantsFruit and seedEasy

Q206In a maize grain the embryonic axis has protective sheaths. Which of these correctly names the sheath that covers the plumule and the sheath that covers the radicle?

BiologyMorphology of Flowering PlantsFloral formula and SolanaceaeHard

Q207The floral formula of a Solanaceae flower is ⊕ ⚥ K(5) C(5) A5 G(2), with the stamens epipetalous and the ovary superior. Which description fits it?

PhysicsMotion in a PlaneAdding vectors analyticallyEasy

Q208Two forces of magnitudes 3 N and 4 N act on a particle, with an angle of 60° between them. The magnitude of their resultant is closest to

PhysicsMotion in a PlaneProjectile motionEasy

Q209A ball is thrown with speed v₀ at angle θ₀ above the horizontal (air resistance negligible). At the highest point of its path, which statement about its velocity and acceleration is correct?

PhysicsMotion in a PlaneUniform circular motionEasy

Q210A small stone tied to a 0.50 m string is whirled in a horizontal circle at a steady 2.0 revolutions per second. The magnitude of its centripetal acceleration is

PhysicsMotion in a PlaneResolving vectors into componentsMedium

Q211Two vectors are A = 3î + 4ĵ and B = î − 2ĵ. The magnitude of 2A − B is

PhysicsMotion in a PlaneProjectile motionMedium

Q212Two balls are projected from level ground with the same speed, one at 30° and the other at 60° to the horizontal. If R₁, H₁ belong to the 30° ball and R₂, H₂ to the 60° ball, then R₁ : R₂ and H₁ : H₂ are

PhysicsMotion in a PlaneProjectile motionMedium

Q213A stone is thrown horizontally at 15 m s⁻¹ from the top of a cliff 45 m high. Take g = 10 m s⁻² and neglect air resistance. With what speed does it hit the ground below?

PhysicsMotion in a PlaneUniform circular motionMedium

Q214A stone whirls round a horizontal circle at constant speed. Is its acceleration a constant vector? Evaluate the Assertion (A) and the Reason (R) given for it.

Assertion (A): The acceleration of a body in uniform circular motion is constant.
Reason (R): The speed of a body in uniform circular motion is constant.

PhysicsMotion in a PlaneProjectile motionMedium

Q215A projectile is launched from level ground and lands back on the same level; air resistance is negligible. Consider statements I to IV and select the option that names every correct statement and no incorrect one.

I. The horizontal component of the projectile's velocity stays constant.
II. The time of flight depends only on the vertical component of the launch velocity.
III. The speed of the projectile at the highest point is zero.
IV. For a given launch speed, the range is maximum at a launch angle of 45°.

PhysicsMotion in a PlaneConstant acceleration in a planeHard

Q216The position of a particle moving in the x-y plane is r(t) = (3t) î + (4t − 5t²) ĵ, with r in metres and t in seconds. At the instant its velocity is perpendicular to its acceleration, what are the particle's speed and position?

PhysicsMotion in a PlaneAdding vectors analyticallyHard

Q217The resultant of two vectors A and B is perpendicular to A, and its magnitude is half the magnitude of B. The angle between A and B is

PhysicsMotion in a Straight LineAverage velocity and average speedEasy

Q218A cyclist rides 3.0 km due east along a straight road in 10 min, then turns around and rides 1.0 km due west along the same road in 5 min. For the whole 15-minute trip, what are the cyclist's average speed and the magnitude of the average velocity?

PhysicsMotion in a Straight LineKinematic equations for uniformly accelerated motionEasy

Q219A car moving at 54 km/h on a straight level road brakes with constant deceleration and comes to rest after travelling 45 m. What is the magnitude of the deceleration?

PhysicsMotion in a Straight LinePosition-time and velocity-time graphsEasy

Q220A student reviewing kinematics graphs for a body moving along a straight line writes four claims, labelled I to IV below. Identify which of the student's claims are physically correct.

I. The area under a velocity-time graph over an interval equals the displacement in that interval.
II. The slope of a position-time graph at an instant equals the acceleration at that instant.
III. A body can have zero velocity and a non-zero acceleration at the same instant.
IV. If the velocity and acceleration of a body have opposite signs, the body is speeding up.

PhysicsMotion in a Straight LineFree fallMedium

Q221A stone is released from rest at the top of a tower and falls freely to the ground. In the last one second of its fall it covers 35 m. Neglect air resistance and take g = 10 m s⁻². What is the height of the tower?

PhysicsMotion in a Straight LineVertical motion under gravityMedium

Q222A ball is thrown vertically upward at 15 m/s from the edge of a cliff 20 m above flat ground. On the way down it just misses the cliff edge and lands on the ground at the foot of the cliff. Neglect air resistance and take g = 10 m s⁻². How long after the throw does the ball hit the ground?

PhysicsMotion in a Straight LineUniform motion: position as a function of timeMedium

Q223On a straight two-lane highway, a bus 12 m long travelling at 72 km/h overtakes a truck 18 m long travelling at 54 km/h in the same direction. Overtaking starts when the front of the bus is level with the rear of the truck and ends when the rear of the bus is level with the front of the truck. Both speeds stay constant. How long does the overtaking take?

PhysicsMotion in a Straight LineAccelerationMedium

Q224Read the Assertion (A) and Reason (R) about a ball thrown vertically upward, with air resistance neglected, and choose the correct option.

Assertion (A): At the highest point of its flight, the acceleration of the ball is zero.
Reason (R): At the highest point of its flight, the velocity of the ball is zero.

PhysicsMotion in a Straight LineVelocity-time graph and uniformly accelerated motionHard

Q225A car starts from rest on a straight road and accelerates uniformly at 2 m s⁻² for some time. It then brakes immediately with a uniform deceleration of 4 m s⁻² until it stops. The whole journey, from start to stop, lasts 12 s. What total distance does the car cover?

PhysicsMotion in a Straight LineInstantaneous velocity; distance vs displacementHard

Q226A particle moves along the x-axis with position x = 6t² − t³, where x is in metres and t in seconds. What is the total distance (path length) travelled by the particle between t = 0 and t = 6 s?

BiologyNeural Control and CoordinationResting potentialEasy

Q227The sodium-potassium pump maintains the resting membrane potential of a neuron. How many ions does it move in each cycle?

BiologyNeural Control and CoordinationThe brainEasy

Q228The brain is covered by three layers of meninges. Which is the correct order from the outermost to the innermost?

BiologyNeural Control and CoordinationThe brainMedium

Q229Match each part of the brain with its function or description.

Column I

Column II

P. Hypothalamus

1. Contains centres that control body temperature and the urge for eating and drinking

Q. Corpus callosum

2. Tract of nerve fibres connecting the two cerebral hemispheres

R. Cerebellum

3. Very convoluted surface that provides space for many more neurons

S. Medulla oblongata

4. Contains centres that control respiration, cardiovascular reflexes and gastric secretions

BiologyNeural Control and CoordinationNerve impulseMedium

Q230Consider the changes in a nerve fibre when a stimulus is applied.

Statement I: When a stimulus is applied, the membrane becomes freely permeable to Na⁺, so Na⁺ rushes in and the polarity of the membrane is reversed.
Statement II: Resting potential is restored by the rapid inflow of K⁺ ions into the axon.

BiologyNeural Control and CoordinationTransmission of impulsesMedium

Q231At a chemical synapse, an arriving action potential triggers a sequence of events. Which sequence is correct?

BiologyNeural Control and CoordinationForebrainMedium

Q232The forebrain consists of the cerebrum, thalamus and hypothalamus. Which of these is the major coordinating centre for sensory and motor signalling?

BiologyNeural Control and CoordinationStructure of a neuronMedium

Q233Axons may be myelinated or non-myelinated. Evaluate the Assertion and Reason.

Assertion (A): Myelinated nerve fibres are found in spinal and cranial nerves.
Reason (R): The gaps between two adjacent myelin sheaths along an axon are called nodes of Ranvier.

BiologyNeural Control and CoordinationTransmission of impulsesHard

Q234Which statement correctly compares electrical and chemical synapses?

BiologyNeural Control and CoordinationStructure of a neuronEasy

Q235In a neuron, which part carries impulses towards the cell body, and which carries them away from it?

BiologyNeural Control and CoordinationForebrainHard

Q236Which statement about the cerebral cortex is correct?

ChemistryOrganic Chemistry – Some Basic Principles and TechniquesIUPAC nomenclatureEasy

Q237A student draws (CH₃)₂CH–CH₂–CH₃ and is unsure whether it is a straight-chain or branched alkane. What is its correct IUPAC name?

ChemistryOrganic Chemistry – Some Basic Principles and TechniquesPurification techniquesEasy

Q238Two completely miscible organic liquids have boiling points differing by only 8 K. Which technique is most suitable for separating them?

ChemistryOrganic Chemistry – Some Basic Principles and TechniquesInductive effectEasy

Q239Among F, Cl, Br, and I, which halogen shows the strongest −I (electron-withdrawing inductive) effect when directly attached to a carbon chain?

ChemistryOrganic Chemistry – Some Basic Principles and TechniquesCarbocation stabilityMedium

Q240Which of the following carbocations is the most stable: CH₃⁺ (methyl), CH₃–CH₂⁺ (ethyl, 1°), (CH₃)₂CH⁺ (isopropyl, 2°), or (CH₃)₃C⁺ (tert-butyl, 3°)?

ChemistryOrganic Chemistry – Some Basic Principles and TechniquesResonanceMedium

Q241In the acetate ion, CH₃COO⁻, both carbon–oxygen bonds are experimentally found to be equal in length, intermediate between a typical C–O single bond and a C=O double bond. What best explains this observation?

ChemistryOrganic Chemistry – Some Basic Principles and TechniquesIsomerismMedium

Q242How many structurally isomeric alcohols (compounds containing an –OH group, excluding ethers) have the molecular formula C₄H₁₀O?

ChemistryOrganic Chemistry – Some Basic Principles and TechniquesInductive effectMedium

Q243The Assertion (A) and Reason (R) below concern how far the inductive effect reaches along a carbon chain. Read them and choose the option that correctly describes their relationship.

Assertion (A): The inductive effect of a substituent becomes negligible after about three bonds along a carbon chain.
Reason (R): The inductive effect is a permanent polarisation transmitted through σ bonds, and the displacement of electron density falls off rapidly with each additional bond from the substituent.

ChemistryOrganic Chemistry – Some Basic Principles and TechniquesResonance / carbocation stabilityHard

Q244Allyl chloride (CH₂=CH–CH₂–Cl) ionises to give the allyl cation, represented by the two resonance structures CH₂=CH–CH₂⁺ ↔ ⁺CH₂–CH=CH₂. Which statement about this cation is correct?

ChemistryOrganic Chemistry – Some Basic Principles and TechniquesIUPAC nomenclatureHard

Q245A five-carbon chain carries a C=C double bond and a chlorine atom: CH₃–CH=CH–CHCl–CH₃. The compound has no principal characteristic group (chloro is always cited as a prefix). What is its correct IUPAC name?

PhysicsOscillationsForce law for SHM: F = −kxEasy

Q246A 0.50 kg block attached to a spring of force constant 200 N m⁻¹ oscillates on a smooth horizontal surface. Its period of oscillation is about

PhysicsOscillationsThe simple pendulumEasy

Q247The bob of a simple pendulum is replaced by one of the same size but four times the mass. The length and the small amplitude are unchanged. The new period is

PhysicsOscillationsVelocity and acceleration in SHMEasy

Q248A particle performs SHM along a straight line about its mean position O. Which of the claims I to IV about how its displacement, velocity and acceleration are related are correct?

I. The speed of the particle is maximum at O.
II. The magnitude of its acceleration is maximum at the extreme positions.
III. Its velocity and displacement are in phase.
IV. Its acceleration and displacement are opposite in phase.

PhysicsOscillationsVelocity and acceleration in SHMMedium

Q249A particle executes SHM with amplitude 10 cm and angular frequency 4.0 rad s⁻¹. Its speed when it is 6.0 cm from the mean position is

PhysicsOscillationsEnergy in SHMMedium

Q250For a particle in SHM of amplitude A, at what distance from the mean position is its kinetic energy three times its potential energy?

PhysicsOscillationsEnergy in SHMMedium

Q251A block on a spring oscillates with period T. Decide whether the Assertion (A) about how often its kinetic energy repeats is true, and whether the trigonometric Reason (R) explains it.

Assertion (A): The kinetic energy of a particle in SHM varies periodically with a period of T/2.
Reason (R): For x = A cos(ωt + φ), the kinetic energy is proportional to sin²(ωt + φ), and sin² repeats every half period of the motion.

PhysicsOscillationsSimple harmonic motion: amplitude, phase and angular frequencyMedium

Q252The displacement of a particle is x(t) = 3 sin ωt + 4 cos ωt, in centimetres. The motion is simple harmonic with amplitude

PhysicsOscillationsSimple harmonic motion: amplitude, phase and angular frequencyMedium

Q253Which one of the following functions of time represents simple harmonic motion (ω is a positive constant)?

PhysicsOscillationsForce law for SHM: F = −kxHard

Q254A 0.25 kg block on a smooth horizontal table is attached between two identical springs, each of force constant 50 N m⁻¹, whose far ends are fixed to walls. The block is pulled 4.0 cm to one side and released. Its maximum speed is

PhysicsOscillationsThe simple pendulumHard

Q255A simple pendulum clock that keeps correct time on the earth is taken to a planet where the acceleration due to gravity is one-quarter of the earth's value. During 24 hours of true time on that planet, the clock

BiologyPhotosynthesis in Higher PlantsWhere does photosynthesis take placeEasy

Q256Within the chloroplast, the light reactions of photosynthesis and the carbon-fixation reactions occur in two distinct sub-compartments. Where do these two sets of reactions respectively take place?

BiologyPhotosynthesis in Higher PlantsPigments involved in photosynthesisEasy

Q257Photosynthetic pigments can be separated into distinct coloured bands by paper chromatography. Among chlorophyll a, chlorophyll b, xanthophyll, and carotenoid, which one is regarded as the chief pigment because it participates directly in converting light energy to chemical energy?

BiologyPhotosynthesis in Higher PlantsEarly experiments — van NielMedium

Q258Cornelius van Niel studied purple and green sulphur bacteria, which photosynthesise using H₂S instead of H₂O as the hydrogen donor and release sulphur or sulphate, not O₂. He summarised photosynthesis as 2H₂A + CO₂ → 2A + CH₂O + H₂O (in light), where H₂A is the hydrogen donor. What did he infer about the O₂ released by green plants?

BiologyPhotosynthesis in Higher PlantsLight reaction — photosystemsMedium

Q259Photosystem I and Photosystem II each have a reaction-centre chlorophyll a molecule, named after the wavelength at which it shows its absorption peak. Which of the following correctly pairs each photosystem with its reaction-centre pigment and identifies the photosystem associated with the splitting of water into O₂, H⁺ and electrons?

BiologyPhotosynthesis in Higher PlantsThe electron transport — photophosphorylationMedium

Q260The light reaction of photosynthesis can proceed along two alternative electron-flow routes through the photosystems, each yielding a different set of products. Evaluate the two statements below on these two routes.

Statement I: Non-cyclic photophosphorylation involves both Photosystem I and Photosystem II acting in series and generates ATP, NADPH, and O₂.
Statement II: Cyclic photophosphorylation involves only Photosystem I, produces only ATP with no NADPH or O₂ formed, and can occur in regions such as the stroma lamellae, which lack Photosystem II.

BiologyPhotosynthesis in Higher PlantsCalvin cycle (C₃ pathway)Medium

Q261The biosynthetic phase of photosynthesis begins when a specific five-carbon acceptor molecule reacts with CO₂ in the chloroplast stroma. Evaluate the two statements below on this carbon-fixation step.

Statement I: The primary CO₂ acceptor of the Calvin cycle is ribulose-1,5-bisphosphate (RuBP), a five-carbon sugar, and the enzyme catalysing its carboxylation is RuBisCO.
Statement II: The first stable product formed when CO₂ combines with RuBP is a three-carbon compound, 3-phosphoglyceric acid (3-PGA), which is why this pathway is also called the C₃ pathway.

BiologyPhotosynthesis in Higher PlantsThe C₄ pathwayHard

Q262Plants such as maize and sugarcane show Kranz anatomy. They first fix CO₂ in their mesophyll cells using PEP carboxylase (PEPcase), and the Calvin cycle then operates in their bundle sheath cells. Which of the following correctly explains why this two-step strategy gives C₄ plants better productivity than C₃ plants?

BiologyPhotosynthesis in Higher PlantsPhotorespirationHard

Q263RuBisCO's active site can bind both CO₂ and O₂, and the relative concentration of the two gases decides which one binds. Evaluate the following Assertion and Reason about what happens in C₃ plants when O₂ binds instead.

Assertion (A): Photorespiration in C₃ plants is regarded as a wasteful process that lowers the net amount of CO₂ fixed.
Reason (R): In the photorespiratory pathway there is neither synthesis of sugars nor of ATP; instead it results in the release of CO₂ with the utilisation of ATP.

BiologyPhotosynthesis in Higher PlantsATP synthesis — chemiosmotic hypothesisMedium

Q264According to the chemiosmotic hypothesis of ATP synthesis in chloroplasts, protons (H⁺) accumulate in a particular compartment during the light reaction, creating a gradient that drives ATP synthase. In which compartment do these protons accumulate, and in which direction do they move to synthesise ATP?

BiologyPhotosynthesis in Higher PlantsFactors affecting photosynthesisEasy

Q265A crop is grown under bright sunlight with adequate water, but the surrounding air has an unusually low CO₂ concentration. According to Blackman's Law of Limiting Factors, what would you expect to happen to the rate of photosynthesis if light intensity is increased further while CO₂ availability stays low?

BiologyPlant Growth and DevelopmentGibberellins and cytokininsEasy

Q266Japanese scientists studying 'foolish seedling' (bakanae) disease of rice, caused by the fungus Gibberella fujikuroi, discovered a plant growth regulator. Which one is it?

BiologyPlant Growth and DevelopmentEthylene and abscisic acidEasy

Q267Which plant growth regulator is called the stress hormone because it closes stomata under water deficit and also induces seed dormancy?

BiologyPlant Growth and DevelopmentPlant growth regulators and their discoveryMedium

Q268Match each plant growth regulator with the scientist or group whose work is linked to its discovery.

Column I

Column II

P. Auxin

1. F.W. Went

Q. Gibberellin

2. E. Kurosawa

R. Cytokinin (kinetin)

3. Skoog and Miller

S. Ethylene

4. H.H. Cousins

BiologyPlant Growth and DevelopmentArithmetic and geometric growthMedium

Q269Growth can follow different mathematical patterns. Evaluate the statements.

Statement I: In arithmetic growth, only one daughter cell continues to divide after mitosis, and the length increases as Lt = L0 + rt, which gives a linear curve.
Statement II: Geometric growth has only a lag phase and a stationary phase, and its curve is a straight line.

BiologyPlant Growth and DevelopmentAbsolute and relative growth rateMedium

Q270Two leaves A and B have initial areas of 5 cm² and 10 cm². In one week A grows to 10 cm² and B grows to 15 cm². Which statement is correct?

BiologyPlant Growth and DevelopmentDifferentiation, dedifferentiation and redifferentiationMedium

Q271In a dicot stem, the interfascicular cambium and the cork cambium arise from fully differentiated parenchyma cells that regain the capacity to divide. What is this process called?

BiologyPlant Growth and DevelopmentGrowth and why it never stops in plantsMedium

Q272Plant growth is termed open, in contrast to the determinate growth of most animals. Evaluate the Assertion and Reason.

Assertion (A): Plants show an open form of growth.
Reason (R): Meristems at certain locations in the plant body retain the capacity to divide throughout the life of the plant.

BiologyPlant Growth and DevelopmentDevelopment and plasticityHard

Q273Cotton, coriander and buttercup all show heterophylly (different leaf forms on the same plant), but not for the same reason. Which statement correctly gives the cause in each?

BiologyPlant Growth and DevelopmentEthylene and abscisic acidEasy

Q274Which plant growth regulator is a gaseous hormone, hastens fruit ripening and promotes the respiratory climacteric in fruits?

BiologyPlant Growth and DevelopmentArithmetic and geometric growthHard

Q275In the equation for geometric growth, W₁ = W₀ e^(rt), what do W₀ and r represent?

BiologyPlant KingdomWhy algae matterEasy

Q276Several algae provide commercially useful hydrocolloids. Which of the following is obtained from brown algae?

BiologyPlant KingdomBryophytes: amphibians of the plant kingdomEasy

Q277In the life cycle of a bryophyte such as a moss or liverwort, which phase is the main, dominant plant body?

BiologyPlant KingdomAlgae: body and reproductionMedium

Q278Sexual reproduction in algae is classified by the type of gametes that fuse. Match each type of sexual reproduction with the NCERT example.

Column I

Column II

P. Isogamy with flagellated gametes

1. Some species of Chlamydomonas, with gametes dissimilar in size

Q. Isogamy with non-flagellated gametes

2. Volvox and Fucus

R. Anisogamy

3. Chlamydomonas, with gametes similar in size

S. Oogamy

4. Spirogyra

BiologyPlant KingdomLiverworts and mossesMedium

Q279Mosses show a clear alternation between two phases. Evaluate the following statements.

Statement I: The moss gametophyte has two stages, a creeping protonema that arises from a spore and a leafy stage that develops from it as a lateral bud.
Statement II: The sporophyte of a moss is free-living and independent of the gametophyte for water and food.

BiologyPlant KingdomPteridophytesMedium

Q280The horsetail Equisetum is a pteridophyte. Under NCERT's grouping of pteridophytes, to which class does it belong?

BiologyPlant KingdomHomospory, heterospory and the seed habitMedium

Q281Most pteridophytes produce spores of one kind, but a few produce two kinds of spores, large and small. Which pair of genera is heterosporous?

BiologyPlant KingdomHomospory, heterospory and the seed habitMedium

Q282In some pteridophytes the female gametophyte stays on the plant that produced it. Evaluate the Assertion and Reason.

Assertion (A): In heterosporous pteridophytes such as Selaginella and Salvinia, the retention of the female gametophyte on the parent sporophyte is regarded as a precursor to the seed habit.
Reason (R): In these plants the zygote develops into a young embryo within the female gametophyte while the gametophyte is still retained on the parent sporophyte.

BiologyPlant KingdomGymnosperms: naked seedsHard

Q283Roots of some gymnosperms live in association with other organisms. Which pair of genus and association is correct?

BiologyPlant KingdomLiverworts and mossesEasy

Q284Sphagnum, a moss, is of great economic importance. It is the source of which material used as fuel and packing for live plants?

BiologyPlant KingdomGreen, brown and red algaeHard

Q285Four features are listed for the class Rhodophyceae. Identify the one that does NOT belong to this class.

ChemistryRedox ReactionsOxidation number rulesEasy

Q286In which of these compounds does oxygen carry a positive oxidation number?

ChemistryRedox ReactionsRedox as electron transferEasy

Q287A zinc strip is placed in copper sulphate solution: Zn(s) + Cu²⁺(aq) → Zn²⁺(aq) + Cu(s). Which species acts as the reducing agent?

ChemistryRedox ReactionsTypes of redox reactionsEasy

Q288On standing, hydrogen peroxide slowly breaks down: 2H₂O₂(aq) → 2H₂O(l) + O₂(g). Which type of redox reaction is this best described as?

ChemistryRedox ReactionsFractional oxidation numbersMedium

Q289Tetrathionate ion, S₄O₆²⁻, is formed when iodine oxidises thiosulphate. What is the average oxidation number of sulphur in S₄O₆²⁻?

ChemistryRedox ReactionsBalancing redox reactionsMedium

Q290Acidified permanganate oxidises oxalate ions to carbon dioxide, itself being reduced to Mn²⁺. In the balanced ionic equation with the smallest whole numbers, what are the coefficients of MnO₄⁻, C₂O₄²⁻ and H⁺ respectively?

ChemistryRedox ReactionsDisproportionation reactionsMedium

Q291Chlorine, bromine and iodine disproportionate in alkali, but fluorine behaves differently. Judge the Assertion (A) and the Reason (R) below.

Assertion (A): Fluorine does not undergo disproportionation reactions.
Reason (R): Fluorine is the most electronegative element and cannot show a positive oxidation number.

ChemistryRedox ReactionsCompetitive electron transfer reactionsMedium

Q292Rods of zinc and copper are dipped in solutions of metal salts at room temperature. Which of the statements below are correct?

Statement I: A zinc rod in copper sulphate solution becomes coated with copper while the blue colour of the solution fades.
Statement II: A copper rod in silver nitrate solution becomes coated with silver while the solution turns blue.
Statement III: A copper rod in zinc sulphate solution becomes coated with zinc.
Statement IV: The tendency to release electrons decreases in the order Zn > Cu > Ag.

ChemistryRedox ReactionsOxidation number rulesMedium

Q293Several compounds break the usual oxidation-number rules. Match the element in each compound of List I with its oxidation number in List II.

Column I

Column II

P. O in O₂F₂

1. −1

Q. C in C₃O₂

2. +1

R. O in KO₂

3. +4/3

S. H in CaH₂

4. −½

ChemistryRedox ReactionsRedox titrationsHard

Q294What volume of 0.020 M KMnO₄ is needed to oxidise completely 25.0 mL of 0.10 M FeSO₄ in acidic solution?

ChemistryRedox ReactionsRedox couples and electrode potentialsHard

Q295Standard reduction potentials: MnO₄⁻/Mn²⁺ +1.51 V; Cl₂/Cl⁻ +1.36 V; Cr₂O₇²⁻/Cr³⁺ +1.33 V; Ag⁺/Ag +0.80 V. Under standard conditions in acid, which of these oxidising agents can oxidise Cl⁻ to Cl₂?

BiologyRespiration in PlantsGlycolysisEasy

Q296Glycolysis is the partial oxidation of glucose to pyruvic acid. Where does it occur in the cell, and what is the net gain of ATP per glucose molecule?

BiologyRespiration in PlantsTricarboxylic acid cycleEasy

Q297Where in the mitochondrion do the link reaction (pyruvic acid to acetyl CoA) and Krebs' cycle take place?

BiologyRespiration in PlantsAerobic respiration: pyruvate to acetyl CoAMedium

Q298Match each reaction of respiration with the enzyme that catalyses it.

Column I

Column II

P. Pyruvic acid to acetyl CoA

1. Hexokinase

Q. Acetyl CoA + OAA to citric acid

2. Invertase

R. Glucose to glucose-6-phosphate

3. Pyruvic dehydrogenase

S. Sucrose to glucose + fructose

4. Citrate synthase

BiologyRespiration in PlantsElectron transport system and oxidative phosphorylationMedium

Q299Consider the following about the oxidation of acetyl CoA and the electron transport system.

Statement I: In each turn of Krebs' cycle, three NADH, one FADH₂ and one GTP (which can be converted to ATP) are produced.
Statement II: Oxygen is used in glycolysis as the final hydrogen acceptor, and the ETS operates on the outer mitochondrial membrane.

BiologyRespiration in PlantsRespiratory quotientMedium

Q300When a fat such as tripalmitin is the respiratory substrate and is completely oxidised, the volume of O₂ consumed exceeds the volume of CO₂ released. What is the approximate RQ?

BiologyRespiration in PlantsFermentationMedium

Q301A student compares alcoholic fermentation in yeast with complete aerobic respiration of glucose. Which statement is correct?

BiologyRespiration in PlantsAmphibolic pathwayHard

Q302Respiratory intermediates are drawn off for synthesis of other compounds. Evaluate the Assertion and Reason.

Assertion (A): The respiratory pathway is considered amphibolic rather than purely catabolic.
Reason (R): Fatty acids are broken down to acetyl CoA for respiration, and acetyl CoA is also withdrawn from the pathway to synthesise fatty acids.

BiologyRespiration in PlantsElectron transport system and oxidative phosphorylationHard

Q303Using the NCERT values of 3 ATP per NADH and 2 ATP per FADH₂ in the ETS, how many ATP are produced by oxidative phosphorylation from the NADH and FADH₂ formed in the link reaction and Krebs' cycle, per glucose molecule? (Ignore glycolysis and the GTP of the cycle.)

BiologyRespiration in PlantsElectron transport system and oxidative phosphorylationMedium

Q304ATP synthase (complex V) of the inner mitochondrial membrane has two major components. Which statement correctly describes them?

BiologyRespiration in PlantsAmphibolic pathwayEasy

Q305When fats are used as the respiratory substrate, in what form do the fatty acids enter the respiratory pathway?

ChemistrySome Basic Concepts of ChemistryMole concept and molar massesEasy

Q306How many hydrogen atoms are present in 5.1 g of ammonia (NH₃)? (N = 14 u, H = 1 u, Nᴀ = 6.022 × 10²³ mol⁻¹)

ChemistrySome Basic Concepts of ChemistryUncertainty in measurement: significant figuresEasy

Q307A mass is recorded as 0.020300 g. How many significant figures does this reading contain?

ChemistrySome Basic Concepts of ChemistryLimiting reagentMedium

Q3085.4 g of aluminium is heated with 14.2 g of chlorine gas. The reaction is 2Al(s) + 3Cl₂(g) → 2AlCl₃(s). What is the maximum mass of AlCl₃ that can be formed? (Al = 27 u, Cl = 35.5 u)

ChemistrySome Basic Concepts of ChemistryReactions in solutions: molarityMedium

Q30912.0 g of urea (molar mass 60 g mol⁻¹) is dissolved in 200 g of water. The density of the resulting solution is 1.05 g mL⁻¹. What is the molarity of the solution?

ChemistrySome Basic Concepts of ChemistryEmpirical and molecular formulaMedium

Q310An organic compound contains 54.5% carbon, 9.1% hydrogen and 36.4% oxygen by mass. Its vapour density (relative to hydrogen) is 44. What is its molecular formula? (C = 12 u, H = 1 u, O = 16 u)

ChemistrySome Basic Concepts of ChemistryLaws of chemical combinationsEasy

Q311Which observation is a direct illustration of the law of multiple proportions?

ChemistrySome Basic Concepts of ChemistryAtomic and molecular massesMedium

Q312Consider the following statements: Which of the statements are correct?

Statement I: One atomic mass unit (u) is defined as exactly one-twelfth of the mass of one carbon-12 atom.
Statement II: The molar mass of a substance in g mol⁻¹ is numerically equal to its molecular (or formula) mass in u.
Statement III: One mole of O₂ gas contains 6.022 × 10²³ oxygen atoms.
Statement IV: The atomic mass of chlorine is 35.5 u because every chlorine atom has a mass of 35.5 u.

ChemistrySome Basic Concepts of ChemistryReactions in solutions: molarity to molalityHard

Q313An aqueous solution of NaCl is 3.00 M and has a density of 1.25 g mL⁻¹. What is its molality? (Molar mass of NaCl = 58.5 g mol⁻¹)

ChemistrySome Basic Concepts of ChemistryStoichiometry with purity and limiting reagentHard

Q31425.0 g of a limestone sample that is 80% CaCO₃ by mass (the rest is unreactive) is treated with 200 mL of 1.5 M HCl. CaCO₃(s) + 2HCl(aq) → CaCl₂(aq) + H₂O(l) + CO₂(g) What volume of CO₂ is released? Take the molar volume of a gas under the conditions of the experiment as 22.7 L mol⁻¹. (Ca = 40 u, C = 12 u, O = 16 u)

BiologyStructural Organisation in AnimalsExternal features of the frogEasy

Q315How many digits are present on the fore limb and on the hind limb of a frog?

BiologyStructural Organisation in AnimalsCirculation, blood and lymphEasy

Q316The heart of a frog is a muscular structure situated in the upper part of the body cavity. How many chambers does it have?

BiologyStructural Organisation in AnimalsExternal features of the frogMedium

Q317Match each structure of the frog with its role or description.

Column I

Column II

P. Tympanum

1. Receives sound signals

Q. Nictitating membrane

2. Protects the eye while in water

R. Vocal sacs

3. Sound-producing sacs present only in the male

S. Copulatory pad

4. Present on the first digit of each fore limb of the male

BiologyStructural Organisation in AnimalsRespirationMedium

Q318The frog is amphibious and uses different respiratory surfaces. Evaluate the statements.

Statement I: A frog does not drink water but absorbs it through its moist, mucus-covered skin.
Statement II: On land a frog respires only through its skin, and the lungs and buccal cavity do not take part in gas exchange.

BiologyStructural Organisation in AnimalsCirculation, blood and lymphMedium

Q319Which pair of portal systems is present in the circulatory system of a frog?

BiologyStructural Organisation in AnimalsExcretory systemMedium

Q320In a male frog, which structure carries both urine and sperms to the cloaca?

BiologyStructural Organisation in AnimalsDigestive systemMedium

Q321The frog's alimentary canal is relatively short. Evaluate the Assertion and Reason.

Assertion (A): The alimentary canal of a frog is short.
Reason (R): The frog is a carnivore, and carnivores need only a short intestine.

BiologyStructural Organisation in AnimalsNervous and endocrine controlHard

Q322Four statements describe the brain and cranial nerves of a frog. Which one is INCORRECT?

BiologyStructural Organisation in AnimalsThe frog and its way of lifeEasy

Q323During the summer, a frog goes into a deep burrow to protect itself from heat and dryness. What is this summer sleep called?

BiologyStructural Organisation in AnimalsCirculation, blood and lymphHard

Q324In the heart of a frog, the sinus venosus and the conus arteriosus are accessory structures. Which description of them is correct?

ChemistryStructure of AtomQuantum numbersEasy

Q325Which set of quantum numbers (n, l, mₗ, mₛ) is NOT possible for an electron in an atom?

ChemistryStructure of AtomIsotopes and isobarsEasy

Q326Which pair of species are isobars?

ChemistryStructure of AtomPlanck's quantum theoryEasy

Q327What is the energy of one photon of ultraviolet light of wavelength 300 nm? (h = 6.626 × 10⁻³⁴ J s, c = 3.0 × 10⁸ m s⁻¹)

ChemistryStructure of AtomBohr's model for hydrogen-like ionsMedium

Q328Using Eₙ = −2.18 × 10⁻¹⁸ (Z²/n²) J, what is the energy of the electron in the second Bohr orbit (n = 2) of He⁺?

ChemistryStructure of AtomLine spectrum of hydrogenMedium

Q329An electron in a hydrogen atom drops from n = 4 to n = 2. Taking the Rydberg constant as 109 677 cm⁻¹, what is the wavenumber of the line emitted?

ChemistryStructure of AtomDual behaviour of matterMedium

Q330What is the de Broglie wavelength of an electron (mass 9.11 × 10⁻³¹ kg) moving at 2.0 × 10⁶ m s⁻¹? (h = 6.626 × 10⁻³⁴ J s)

ChemistryStructure of AtomStability of half-filled and fully filled orbitalsMedium

Q331Chromium breaks the simple aufbau filling order in its ground state. Judge the Assertion (A) and the Reason (R) below.

Assertion (A): The ground-state configuration of chromium (Z = 24) is [Ar]3d⁵4s¹ rather than [Ar]3d⁴4s².
Reason (R): Exactly half-filled subshells are extra stable because of their symmetrical distribution and larger exchange energy.

ChemistryStructure of AtomPhotoelectric effectMedium

Q332Light of different frequencies and intensities falls on a clean metal surface. Which of the statements about the photoelectric effect are correct?

Statement I: Increasing the intensity of light of a fixed frequency increases the kinetic energy of the ejected electrons.
Statement II: Light below the threshold frequency ejects no electrons, however intense it is.
Statement III: Above the threshold frequency, the number of electrons ejected per second rises with the intensity of light.
Statement IV: Electrons are ejected as soon as suitable light strikes the metal, with no measurable time lag.

ChemistryStructure of AtomShapes of atomic orbitalsHard

Q333Match each hydrogen-like orbital in List I with the number of radial and angular nodes it has in List II.

Column I

Column II

P. 3s

1. 1 radial, 2 angular

Q. 3p

2. 0 radial, 3 angular

R. 4d

3. 2 radial, 0 angular

S. 4f

4. 1 radial, 1 angular

ChemistryStructure of AtomHeisenberg's uncertainty principleHard

Q334An electron is known to lie within a region of width 0.10 nm. What is the minimum uncertainty in its velocity? (h = 6.626 × 10⁻³⁴ J s, mₑ = 9.11 × 10⁻³¹ kg, π = 3.14)

PhysicsSystem of Particles and Rotational MotionCentre of massEasy

Q335A 2 kg particle sits at x = 0 and a 3 kg particle at x = 5 m on the x-axis. Where is the centre of mass of the pair?

PhysicsSystem of Particles and Rotational MotionTorque and angular momentumEasy

Q336A force of 20 N is applied at the free end of a 0.50 m spanner, at an angle of 30° to the length of the spanner, in the plane of rotation. The magnitude of the torque about the nut is

PhysicsSystem of Particles and Rotational MotionMoment of inertiaEasy

Q337A metre stick is easy to twirl about its own length but hard to swing about an axis through its middle at right angles. Judge the Assertion (A) and Reason (R) about the moment of inertia behind this.

Assertion (A): The moment of inertia of a rigid body is not a fixed quantity; it depends on the axis of rotation.
Reason (R): The moment of inertia depends on how the body's mass is distributed about the axis of rotation.

PhysicsSystem of Particles and Rotational MotionKinematics of rotationMedium

Q338A grinding wheel spinning at 600 rpm is switched off and comes to rest in 10 s with uniform angular deceleration. How many revolutions does it make while stopping?

PhysicsSystem of Particles and Rotational MotionAngular momentum and its conservationMedium

Q339A skater spins at 1.5 rev s⁻¹ with arms outstretched, when her moment of inertia about the vertical axis is 4.0 kg m². She pulls her arms in, reducing it to 2.5 kg m². Ignoring friction with the ice, her new rate of spin is

PhysicsSystem of Particles and Rotational MotionDynamics of rotationMedium

Q340A uniform solid disc of mass 4.0 kg and radius 0.50 m can turn freely about a fixed horizontal axle through its centre. A light string wound round its rim is pulled with a steady tangential force of 10 N. The angular acceleration of the disc is

PhysicsSystem of Particles and Rotational MotionMotion of the centre of massMedium

Q341A shell flying along a parabolic path explodes in mid-air into several fragments. Air resistance is negligible. Consider statements I to IV and select the option that names every correct statement and no incorrect one.

I. The centre of mass of the fragments continues along the original parabola until a fragment hits the ground.
II. The total momentum of the fragments just after the explosion equals the shell's momentum just before.
III. The total kinetic energy of the fragments just after the explosion equals the shell's kinetic energy just before.
IV. The forces of the explosion can change the velocity of the centre of mass.

PhysicsSystem of Particles and Rotational MotionPrinciple of moments and centre of gravityMedium

Q342A uniform rod 1.00 m long with mass 400 g is pivoted at its 40 cm mark. What mass must be hung at the 20 cm mark to keep the rod horizontal?

PhysicsSystem of Particles and Rotational MotionVector product of two vectorsHard

Q343A force F = (î − ĵ + k̂) N acts at a point whose position vector relative to the origin is r = (2î + 3ĵ) m. The torque of the force about the origin is

PhysicsSystem of Particles and Rotational MotionAngular momentum and its conservationHard

Q344A disc with moment of inertia I spins freely at ω₀ about a frictionless vertical axle. A second disc, at rest and with moment of inertia 2I about the same axle, is dropped gently onto it, and the two soon rotate together. What fraction of the initial kinetic energy is lost?

BiologyThe Living WorldBinomial nomenclatureEasy

Q345A herbarium label reads 'Mangifera indica Linn.' What does the abbreviation 'Linn.' at the end of the name indicate?

BiologyThe Living WorldBinomial nomenclatureEasy

Q346A student handwrites the scientific name of humans, Homo sapiens, in an answer sheet. How should the name be underlined according to the convention for handwritten names?

BiologyThe Living WorldTaxonomic categories and hierarchyMedium

Q347Which sequence lists the taxonomic categories correctly from the lowest rank to the highest rank?

BiologyThe Living WorldTaxonomic categories and hierarchyMedium

Q348The hierarchy of taxonomic categories is built on shared characters. Read the two statements below and decide which are correct.

Statement I: As one moves from species up to kingdom, the number of characters shared by the members of a category decreases.
Statement II: A genus is a higher category than a family because it contains more kinds of organisms.

BiologyThe Living WorldFamily, order and classHard

Q349Match each organism with its family as given in the NCERT table of taxonomic categories.

Column I

Column II

P. Housefly

1. Hominidae

Q. Man

2. Poaceae

R. Mango

3. Muscidae

S. Wheat

4. Anacardiaceae

BiologyThe Living WorldFamily, order and classMedium

Q350Solanum, Petunia and Datura are placed in the family Solanaceae. In which order is Solanaceae grouped together with the family Convolvulaceae?

BiologyThe Living WorldPhylum, kingdom and the hierarchy tableMedium

Q351Mango (a dicot) and wheat (a monocot) are different in many ways. What is the lowest category in the NCERT hierarchy that they share?

BiologyThe Living WorldClassification, taxonomy and systematicsMedium

Q352Taxonomy and systematics are related but not identical. Evaluate the following Assertion and Reason.

Assertion (A): Besides identification, nomenclature and classification, systematics also takes into account the evolutionary relationships between organisms.
Reason (R): Linnaeus used 'Systema Naturae' as the title of his publication.

BiologyThe Living WorldFamily, order and classHard

Q353Using the NCERT hierarchy, in which pair do the two organisms belong to the same class but to different orders?

BiologyThe Living WorldBinomial nomenclatureEasy

Q354Two international codes govern the naming of organisms. Which pair gives the code for plants first and the code for animals second?

PhysicsThermal Properties of MatterTemperature, heat and thermometer scalesEasy

Q355The temperature of a cup of milk rises by 40 °C as it is heated. Expressed on the Fahrenheit and Kelvin scales, this rise is

PhysicsThermal Properties of MatterRadiation and blackbody radiationEasy

Q356The radiation from a star, treated as a black body, has its maximum intensity at a wavelength of 500 nm. Using Wien's constant b = 2.9 × 10⁻³ m K, the star's surface temperature is about

PhysicsThermal Properties of MatterAnomalous expansion of water and thermal stressEasy

Q357A pond is cooled by winter air from 10 °C down to freezing. Which of the claims I to IV about how water's density behaves in this range are correct?

I. Water has its maximum density at about 4 °C.
II. When water is cooled from 4 °C to 0 °C, it contracts.
III. A lake freezes from the top downward partly because water colder than 4 °C rises to the surface.
IV. At 0 °C, ice is denser than liquid water.

PhysicsThermal Properties of MatterThermal expansionMedium

Q358A solid metal sphere has a coefficient of linear expansion of 1.2 × 10⁻⁵ K⁻¹. By what percentage does its volume increase when it is heated through 100 K?

PhysicsThermal Properties of MatterCalorimetryMedium

Q35950 g of ice at 0 °C is dropped into 200 g of water at 40 °C in a container of negligible heat capacity, with no heat lost to the surroundings. Take the specific heat of water as 4200 J kg⁻¹ K⁻¹ and the latent heat of fusion of ice as 3.36 × 10⁵ J kg⁻¹. The final temperature of the mixture is

PhysicsThermal Properties of MatterConductionMedium

Q360Two rods of equal length and equal cross-section are joined end to end and insulated along their sides. The rod with thermal conductivity 3K has its free end at 100 °C; the rod with conductivity K has its free end at 0 °C. In the steady state, the equivalent conductivity of the pair and the junction temperature are

PhysicsThermal Properties of MatterNewton's law of coolingHard

Q361A body cools from 80 °C to 60 °C in 5.0 minutes in a room at 20 °C. Using Newton's law of cooling with the average temperature over each interval, how long will it take to cool further from 60 °C to 40 °C?

PhysicsThermal Properties of MatterRadiation and blackbody radiationMedium

Q362A black body at 27 °C is heated to 327 °C. By what factor does the power it radiates increase?

PhysicsThermal Properties of MatterSpecific heat capacityMedium

Q363Match each thermal quantity in List I with its SI unit in List II.

Column I

Column II

P. Specific heat capacity

1. J mol⁻¹ K⁻¹

Q. Molar specific heat capacity

2. J kg⁻¹

R. Thermal conductivity

3. J kg⁻¹ K⁻¹

S. Latent heat

4. W m⁻¹ K⁻¹

PhysicsThermal Properties of MatterAnomalous expansion of water and thermal stressHard

Q364A steel rod of cross-sectional area 2.0 cm² is clamped rigidly between two walls at room temperature and then heated through 50 K. For steel, Y = 2.0 × 10¹¹ N m⁻² and α = 1.2 × 10⁻⁵ K⁻¹. The compressive force the walls exert on the rod is

ChemistryThermodynamicsFirst law of thermodynamicsEasy

Q365A gas in a cylinder absorbs 250 J of heat from the surroundings and, in the same process, does 400 J of work on the surroundings by expanding. What is the change in internal energy of the gas?

ChemistryThermodynamicsEnthalpy: relation between ΔH and ΔUMedium

Q366In a bomb calorimeter at 298 K, the internal energy change for the complete combustion of liquid ethanol is ΔU = −1364.5 kJ mol⁻¹: C₂H₅OH(l) + 3O₂(g) → 2CO₂(g) + 3H₂O(l) What is ΔH for this reaction at 298 K? (R = 8.314 J K⁻¹ mol⁻¹)

ChemistryThermodynamicsHess's law of constant heat summationMedium

Q367Use the following data at 298 K to find the standard enthalpy of formation of propane, C₃H₈(g): ΔcH°[C₃H₈(g)] = −2220.0 kJ mol⁻¹ ΔfH°[CO₂(g)] = −393.5 kJ mol⁻¹ ΔfH°[H₂O(l)] = −285.8 kJ mol⁻¹

ChemistryThermodynamicsGibbs energy and spontaneityEasy

Q368A reaction has ΔH > 0 and ΔS > 0, and both are nearly independent of temperature. Under what conditions is the reaction spontaneous at constant pressure?

ChemistryThermodynamicsGibbs energy: threshold temperatureMedium

Q369A solid decomposes with ΔH° = +178.0 kJ mol⁻¹ and ΔS° = +160.0 J K⁻¹ mol⁻¹. Assuming both are independent of temperature, in which temperature range is the decomposition spontaneous under standard conditions?

ChemistryThermodynamicsWork: isothermal reversible expansion of an ideal gasMedium

Q3702.0 mol of an ideal gas expands isothermally and reversibly at 300 K from 10.0 L to 100.0 L. What is the work done on the gas? (R = 8.314 J K⁻¹ mol⁻¹)

ChemistryThermodynamicsThermodynamic terms and enthalpyHard

Q371Consider the following statements and choose the option that lists ALL the correct ones.

Statement I: In an adiabatic process q = 0, so the change in internal energy equals the work done on the system (ΔU = wₐd).
Statement II: The standard enthalpy of formation of O₃(g) is zero, because ozone is a form of the element oxygen.
Statement III: Heat capacity of a sample is an extensive property, whereas its molar heat capacity is an intensive property.
Statement IV: For N₂(g) + 3H₂(g) → 2NH₃(g) at constant temperature, with all gases behaving ideally, ΔH is less than ΔU.

ChemistryThermodynamicsBond enthalpyHard

Q372Using the mean bond enthalpies below, estimate ΔrH for the gas-phase hydrogenation of ethene: CH₂=CH₂(g) + H₂(g) → CH₃–CH₃(g) C=C: 614 kJ mol⁻¹; C–C: 348 kJ mol⁻¹; C–H: 413 kJ mol⁻¹; H–H: 436 kJ mol⁻¹

ChemistryThermodynamicsInternal energy as a state functionEasy

Q373A gas is taken from state 1 to state 2 along path X, absorbing 50 J of heat while doing 20 J of work on the surroundings. It is then returned to state 1 and taken to state 2 again along path Y, on which it does 45 J of work on the surroundings. How much heat does the gas absorb along path Y?

PhysicsThermodynamicsFirst law of thermodynamicsEasy

Q374A gas in a cylinder absorbs 500 J of heat and, at the same time, pushes a piston outward, doing 200 J of work on the surroundings. The change in its internal energy is

PhysicsThermodynamicsCarnot engineEasy

Q375A Carnot engine works between a hot reservoir at 227 °C and a cold reservoir at 27 °C. Its efficiency is

PhysicsThermodynamicsQuasi-static and isothermal processesEasy

Q376An ideal gas expands slowly while kept in contact with a large reservoir at a fixed temperature. Assess the Assertion (A) about where the absorbed heat goes and the Reason (R) offered for it.

Assertion (A): In an isothermal expansion of an ideal gas, all the heat absorbed by the gas is converted into work done by it.
Reason (R): The internal energy of an ideal gas depends only on its temperature.

PhysicsThermodynamicsSpecific heat capacityMedium

Q377Two moles of a rigid diatomic ideal gas are heated at constant pressure so that their temperature rises by 50 K. Take R = 8.31 J mol⁻¹ K⁻¹. The heat supplied to the gas is about

PhysicsThermodynamicsQuasi-static and isothermal processesMedium

Q378One mole of an ideal gas at 300 K expands isothermally and reversibly from 10 L to 20 L. Take R = 8.31 J mol⁻¹ K⁻¹ and ln 2 = 0.693. The work done by the gas is about

PhysicsThermodynamicsAdiabatic processMedium

Q379A monatomic ideal gas at 300 K is compressed adiabatically and reversibly to one-eighth of its original volume. Its final temperature is

PhysicsThermodynamicsIsochoric, isobaric and cyclic processesMedium

Q380An ideal gas is taken once round a rectangular cycle on a P–V diagram (P on the vertical axis) in the clockwise direction. The pressure switches between 1.0 × 10⁵ Pa and 3.0 × 10⁵ Pa, and the volume between 1.0 L and 4.0 L. The net heat absorbed by the gas in one cycle is

PhysicsThermodynamicsSecond law of thermodynamicsMedium

Q381Which of the claims I to IV about the second law of thermodynamics, Carnot engines and the nature of heat are correct?

I. Heat cannot be drawn from a single reservoir and turned entirely into work as the only outcome of any process.
II. Heat cannot pass from a colder body to a hotter body as the only outcome of any process.
III. A Carnot engine working between two given temperatures can reach 100% efficiency if all friction is removed.
IV. Heat is a thermodynamic state variable.

PhysicsThermodynamicsAdiabatic processHard

Q382Two moles of a monatomic ideal gas expand adiabatically and reversibly, and the temperature falls from 400 K to 300 K. Take R = 8.31 J mol⁻¹ K⁻¹. The work done by the gas is about

PhysicsThermodynamicsCarnot engineHard

Q383A Carnot engine has an efficiency of 40% with its sink at 300 K. Keeping the sink temperature fixed, by how much must the source temperature be raised so that the efficiency becomes 50%?

PhysicsUnits and MeasurementSignificant figuresEasy

Q384A student records the thickness of a sheet as 0.020500 m. How many significant figures does this reading have?

PhysicsUnits and MeasurementDimensions and dimensional formulaeEasy

Q385Which pair of physical quantities has the same dimensional formula?

PhysicsUnits and MeasurementThe SI systemEasy

Q386The SI system is built on seven base units. Which of the units named in statements I to IV are among those seven?

I. The candela is an SI base unit.
II. The radian is an SI base unit.
III. The mole is an SI base unit.
IV. The newton is an SI base unit.

PhysicsUnits and MeasurementArithmetic with significant figuresMedium

Q387The length and breadth of a rectangular tile are measured as 4.234 m and 1.05 m. Its area, reported with the correct number of significant figures, is

PhysicsUnits and MeasurementArithmetic with significant figuresMedium

Q388Three samples with masses 2.3 kg, 0.415 kg and 13.07 kg are placed together on a tray. Their total mass, written with the correct precision, is

PhysicsUnits and MeasurementUncertainty in calculated resultsMedium

Q389The density of a metal cube is found from ρ = m/L³. The mass m is measured with a percentage error of 1% and the side L with a percentage error of 2%. The maximum percentage error in ρ is

PhysicsUnits and MeasurementDimensions and dimensional formulaeMedium

Q390Match each quantity in List I with its dimensional formula in List II.

Column I

Column II

P. Pressure

1. [M L² T⁻³]

Q. Power

2. [M⁻¹ L³ T⁻²]

R. Coefficient of viscosity

3. [M L⁻¹ T⁻²]

S. Gravitational constant G

4. [M L⁻¹ T⁻¹]

PhysicsUnits and MeasurementDeducing relations by dimensionsMedium

Q391Can matching the dimensions of length, g and mass give the complete formula for a pendulum's period? Assess the Assertion (A) and Reason (R).

Assertion (A): The formula T = 2π√(l/g) for a simple pendulum cannot be derived completely by dimensional analysis.
Reason (R): Dimensional analysis gives no information about dimensionless constants.

PhysicsUnits and MeasurementDeducing relations by dimensionsHard

Q392A small liquid drop vibrates when disturbed. Assume its frequency ν depends only on the surface tension S of the liquid (force per unit length), its density ρ and the drop radius r. Dimensional analysis gives ν proportional to

PhysicsUnits and MeasurementChecking dimensional consistencyHard

Q393The speed of a body is given by v = αt + β/(t + γ), where t is time. For this equation to be dimensionally consistent, the dimensions of αγ/β are

PhysicsWavesDisplacement relation of a progressive waveEasy

Q394A wave on a string is described by y(x, t) = 0.05 sin(20x − 400t), with x and y in metres and t in seconds. The speed of the wave is

PhysicsWavesTransverse and longitudinal wavesEasy

Q395Sound travels through air only as compressions and rarefactions. Judge whether the Assertion (A) about transverse mechanical waves in gases holds, and whether the Reason (R) about shearing stress explains it.

Assertion (A): Transverse mechanical waves cannot travel through a gas.
Reason (R): A gas cannot sustain a shearing stress.

PhysicsWavesBeatsEasy

Q396Two sound sources of equal amplitude, with frequencies 340 Hz and 336 Hz, are sounded together. What are the beat frequency and the frequency of the resultant tone whose loudness rises and falls?

PhysicsWavesWave speed on a stretched stringMedium

Q397A string of length 1.25 m and mass 5.0 g is stretched with a tension of 100 N. The speed of transverse waves on it is about

PhysicsWavesHarmonics of strings and pipesMedium

Q398A pipe 0.85 m long is closed at one end and open at the other. The speed of sound in air is 340 m s⁻¹. Which of the following frequencies can NOT be a natural frequency of this pipe?

PhysicsWavesSpeed of sound: Newton and LaplaceMedium

Q399A gas has density 1.25 kg m⁻³ at a pressure of 1.0 × 10⁵ Pa, and its ratio of specific heats is γ = 1.4. Using Laplace's formula, the speed of sound in it is about

PhysicsWavesReflection and standing wavesMedium

Q400A string 1.5 m long, fixed at both ends, vibrates in a standing-wave pattern with three loops (two nodes between the ends). The speed of transverse waves on the string is 120 m s⁻¹. The frequency of vibration is

PhysicsWavesHarmonics of strings and pipesMedium

Q401For each system in List I, the length is L and the wave speed is v. Match each with its frequency in List II.

Column I

Column II

P. String fixed at both ends, fundamental

1. 3v/4L

Q. Pipe open at both ends, second harmonic

2. v/4L

R. Pipe closed at one end, fundamental

3. v/2L

S. Pipe closed at one end, first overtone

4. v/L

PhysicsWavesBeatsHard

Q402A guitar string sounded with a 300 Hz tuning fork gives 4 beats per second. When the tension in the string is slightly reduced, the beats increase to 6 per second. The original frequency of the string was

PhysicsWavesPrinciple of superpositionHard

Q403Two waves y₁ = a sin(kx − ωt) and y₂ = a sin(kx − ωt + 2π/3) travel along the same string. The amplitude of the resultant wave is

PhysicsWork, Energy and PowerWorkEasy

Q404A box is dragged 8.0 m along a straight horizontal floor by a rope. The rope pulls with a constant force of 25 N directed at 60° above the horizontal. How much work does the rope's force do on the box?

PhysicsWork, Energy and PowerKinetic energyEasy

Q405The linear momentum of a body of fixed mass increases by 30%. By what percentage does its kinetic energy increase?

PhysicsWork, Energy and PowerCollisionsEasy

Q406Read the Assertion (A) and Reason (R) about a one-dimensional elastic collision between two bodies of different masses, and choose the correct option.

Assertion (A): In an elastic collision, the kinetic energy of each colliding body is the same before and after the collision.
Reason (R): In an elastic collision, the total kinetic energy of the system is the same before and after the collision.

PhysicsWork, Energy and PowerPotential energy of a springMedium

Q407A 0.50 kg block slides at 2.0 m/s on a smooth horizontal surface and runs head-on into the free end of a light horizontal spring of spring constant 200 N/m. The other end of the spring is fixed to a wall. What is the maximum compression of the spring?

PhysicsWork, Energy and PowerPowerMedium

Q408An electric pump lifts 200 kg of water through a vertical height of 15 m every minute, delivering it at negligible speed. The pump is 75% efficient. Take g = 10 m s⁻². What is the electrical power input to the pump?

PhysicsWork, Energy and PowerWork-energy theoremMedium

Q409A 2.0 kg block is given an initial speed of 6.0 m/s along a rough horizontal floor and slides to rest. The coefficient of kinetic friction between the block and the floor is 0.30. Take g = 10 m s⁻². How far does the block slide?

PhysicsWork, Energy and PowerConservative forces and potential energyMedium

Q410The four claims I to IV below concern conservative forces, potential energy and mechanical energy. Pick the option listing exactly the true claims.

I. The work done by a conservative force on a body moving around any closed path is zero.
II. A potential energy function can be defined only for a conservative force.
III. The total mechanical energy of a body remains constant even while kinetic friction acts on it.
IV. The work done by a conservative force depends only on the initial and final positions of the body.

PhysicsWork, Energy and PowerCollisions (elastic collision in one dimension)Hard

Q411A 2 kg ball moving at 6 m/s on a smooth horizontal track collides head-on, elastically, with a 4 kg ball that is at rest. What fraction of the first ball's initial kinetic energy is transferred to the 4 kg ball?

PhysicsWork, Energy and PowerConservation of mechanical energy with frictionHard

Q412A 0.50 kg block is released from rest at a height of 1.8 m on a smooth curved ramp. At the bottom, the ramp joins a horizontal floor. The block first crosses a rough strip of the floor 2.0 m long, where the coefficient of kinetic friction is 0.20. After that the floor is smooth. On the smooth part, the block runs into a light horizontal spring of spring constant 400 N/m with its far end fixed. Take g = 10 m s⁻². What is the maximum compression of the spring?

ChemistryAlcohols, Phenols and EthersReactions of alcoholsEasy

Q413Which alcohol gives turbidity at once with the Lucas reagent (conc. HCl + ZnCl₂) at room temperature?

ChemistryAlcohols, Phenols and EthersAcidity of alcohols and phenolsEasy

Q414Why is phenol more acidic than ethanol?

ChemistryAlcohols, Phenols and EthersPreparation of ethersEasy

Q415Which pair of reagents is the better choice for making tert-butyl methyl ether by Williamson synthesis?

ChemistryAlcohols, Phenols and EthersAcidity of alcohols and phenolsMedium

Q416Arrange in order of INCREASING acid strength: (I) phenol, (II) 4-nitrophenol, (III) 4-methylphenol, (IV) ethanol.

ChemistryAlcohols, Phenols and EthersOxidation of alcoholsMedium

Q417Butan-2-ol is oxidised with acidified potassium dichromate. What is the main product?

ChemistryAlcohols, Phenols and EthersReactions of phenolsMedium

Q418Phenol is treated with chloroform and aqueous NaOH, and the product is then acidified. What is the main product?

ChemistryAlcohols, Phenols and EthersReactions of phenolsMedium

Q419Phenol reacts with bromine under different conditions to give different products. Judge the Assertion (A) and the Reason (R) below.

Assertion (A): Phenol with bromine water gives a white precipitate of 2,4,6-tribromophenol.
Reason (R): The –OH group activates the benzene ring so strongly that, in a polar solvent such as water, bromine substitutes at every free ortho and para position without a Lewis acid.

ChemistryAlcohols, Phenols and EthersMethanol and ethanolMedium

Q420Methanol and ethanol are the two simplest alcohols of commercial importance. Which of the statements below are correct?

Statement I: Methanol is made by catalytic hydrogenation of carbon monoxide.
Statement II: Fermentation of sugars to ethanol needs a steady supply of air.
Statement III: Yeast enzymes convert sugars into ethanol during fermentation.
Statement IV: Ethanol for industrial use is denatured by mixing it with an equal volume of water.

ChemistryAlcohols, Phenols and EthersReactions of ethersHard

Q421Each ether in List I is heated with one equivalent of HI. Match it with the pair of products in List II.

Column I

Column II

P. CH₃–O–C₂H₅

1. C₆H₅OH + CH₃I

Q. C₆H₅–O–CH₃

2. C₆H₅OH + C₂H₅I

R. (CH₃)₃C–O–CH₃

3. CH₃I + C₂H₅OH

S. C₆H₅–O–C₂H₅

4. (CH₃)₃CI + CH₃OH

ChemistryAlcohols, Phenols and EthersPreparation of alcoholsHard

Q422Propene is treated with diborane, and the product is oxidised with H₂O₂ in aqueous NaOH. Which alcohol forms, and how does it compare with acid-catalysed hydration of propene?

ChemistryAldehydes, Ketones and Carboxylic AcidsNucleophilic additionEasy

Q423Which compound is the most reactive towards nucleophilic addition to the carbonyl group?

ChemistryAldehydes, Ketones and Carboxylic AcidsOxidation and testsEasy

Q424Which compound gives a silver mirror with Tollens' reagent?

ChemistryAldehydes, Ketones and Carboxylic AcidsReduction of carbonyl compoundsEasy

Q425Acetophenone (C₆H₅COCH₃) is heated with zinc amalgam and concentrated HCl. What forms?

ChemistryAldehydes, Ketones and Carboxylic AcidsReactions due to α-hydrogenMedium

Q426Which aldehyde does NOT undergo aldol condensation with dilute NaOH, but undergoes Cannizzaro reaction with concentrated NaOH?

ChemistryAldehydes, Ketones and Carboxylic AcidsOxidation and testsMedium

Q427Which compound gives a yellow precipitate when warmed with iodine and sodium hydroxide?

ChemistryAldehydes, Ketones and Carboxylic AcidsAcidity of carboxylic acidsMedium

Q428Which acid is the strongest?

ChemistryAldehydes, Ketones and Carboxylic AcidsReactions of carboxylic acidsMedium

Q429Carboxylic acids with α-hydrogens can be halogenated using red phosphorus. Judge the Assertion (A) and the Reason (R) below.

Assertion (A): Ethanoic acid treated with Cl₂ and red phosphorus gives chloroethanoic acid.
Reason (R): Carboxylic acids have no α-hydrogens, so halogen must replace the hydrogen of the –COOH group.

ChemistryAldehydes, Ketones and Carboxylic AcidsNucleophilic additionMedium

Q430Aldehydes and ketones react with many nucleophiles. Which of the statements below are correct?

Statement I: Ethanal reacts with HCN to give a cyanohydrin, which on hydrolysis gives 2-hydroxypropanoic acid.
Statement II: Aldehydes and ketones react with hydroxylamine to form oximes.
Statement III: Sodium hydrogensulphite reduces aldehydes to primary alcohols.
Statement IV: Propanone gives a red-brown precipitate with Fehling's solution.

ChemistryAldehydes, Ketones and Carboxylic AcidsPreparation of aldehydes and ketonesHard

Q431Each conversion in List I needs a specific reagent or set of conditions to make an aldehyde or ketone. Match each conversion with the reagents in List II.

Column I

Column II

P. Benzoyl chloride → benzaldehyde

1. CrO₂Cl₂ in CS₂, then H₃O⁺

Q. Ethanenitrile → ethanal

2. H₂, Pd on BaSO₄

R. Toluene → benzaldehyde

3. CH₃COCl, anhydrous AlCl₃

S. Benzene → acetophenone

4. SnCl₂ + HCl, then H₃O⁺

ChemistryAldehydes, Ketones and Carboxylic AcidsCannizzaro reactionHard

Q432A mixture of methanal and benzaldehyde is heated with concentrated NaOH. What are the main products?

PhysicsAlternating CurrentRMS values and average powerEasy

Q433An ac supply has instantaneous voltage v = 311 sin(314t) volts, with t in seconds. What are its rms voltage and frequency?

PhysicsAlternating CurrentAC through a capacitorEasy

Q434What is the reactance of a 10 μF capacitor connected to a 50 Hz ac supply?

PhysicsAlternating CurrentSeries LCR circuit and impedanceMedium

Q435A series LCR circuit has R = 30 Ω, X_L = 80 Ω and X_C = 40 Ω, and is connected to a 100 V (rms) ac supply. What is the rms current?

PhysicsAlternating CurrentResonanceMedium

Q436A series LCR circuit contains an inductor of 0.40 H and a capacitor of 25 μF. At what frequency of the source does resonance occur?

PhysicsAlternating CurrentAC through an inductorMedium

Q437An ideal inductor (no resistance) is connected across an ac source. Read the Assertion (A) and Reason (R) and choose the correct option.

Assertion (A): The average power delivered to the inductor over a complete cycle is zero.
Reason (R): In an ideal inductor the current lags the voltage by π/2, so the power factor cos φ is zero.

PhysicsAlternating CurrentPower factorMedium

Q438A series LCR circuit with R = 40 Ω, X_L = 60 Ω and X_C = 30 Ω is connected to a 200 V (rms) ac supply. What average power does it draw?

PhysicsAlternating CurrentResonanceHard

Q439A series LCR circuit with R = 100 Ω is at resonance at frequency f₀, where X_L = X_C = 100 Ω. The source frequency is now doubled to 2f₀ with the same components. What is the new power factor, and how is the current related to the voltage?

PhysicsAlternating CurrentTransformersMedium

Q440An ideal transformer (no energy losses) has 100 turns on its primary coil and 2000 turns on its secondary coil. The primary is connected to a 230 V (rms) ac supply, and the secondary delivers a current of 0.50 A (rms) to a load. What are the secondary voltage and the primary current?

PhysicsAlternating CurrentPhasorsEasy

Q441Consider the following statements about ac circuits with a single ideal element. Which of them are correct?

I. In a pure resistor, current and voltage are in phase.
II. In a pure inductor, current leads the voltage by π/2.
III. In a pure capacitor, current leads the voltage by π/2.
IV. The length of a phasor represents the peak value of the quantity, and its projection on the vertical axis gives the instantaneous value.

PhysicsAlternating CurrentSeries LCR circuit and impedanceHard

Q442A coil draws 4.0 A when connected to a 12 V dc source. When the same coil is connected to a 12 V (rms), 50 Hz ac source, it draws 2.4 A (rms). What is the inductance of the coil?

ChemistryAminesReactions of aminesEasy

Q443Which compound gives a foul-smelling isocyanide when warmed with chloroform and alcoholic KOH?

ChemistryAminesPreparation of aminesEasy

Q444Why can Gabriel phthalimide synthesis not be used to prepare aniline?

ChemistryAminesPreparation of aminesEasy

Q445Propanamide (CH₃CH₂CONH₂) is treated with Br₂ and aqueous NaOH. What amine forms?

ChemistryAminesBasic character of aminesMedium

Q446Which order of basic strength in aqueous solution is correct?

ChemistryAminesBasic character of aminesMedium

Q447Why is aniline a weaker base than methanamine?

ChemistryAminesElectrophilic substitution in anilineMedium

Q448Direct nitration of aniline with a nitrating mixture gives a considerable amount of meta-nitroaniline. Why?

ChemistryAminesHinsberg's testMedium

Q449Benzenesulphonyl chloride (Hinsberg's reagent) is used to tell apart primary, secondary and tertiary amines. Judge the Assertion (A) and the Reason (R) below.

Assertion (A): The sulphonamide formed from a secondary amine is insoluble in alkali.
Reason (R): The sulphonamide from a secondary amine has no hydrogen on nitrogen that is acidic enough to be removed by alkali.

ChemistryAminesDiazonium saltsMedium

Q450Arenediazonium salts are prepared from aromatic amines and used widely in synthesis. Which of the statements below are correct?

Statement I: Benzenediazonium chloride is prepared from aniline with NaNO₂ and HCl at 273–278 K.
Statement II: The arenediazonium ion is stabilised by resonance with the benzene ring.
Statement III: Primary aliphatic amines form diazonium salts that are stable at room temperature.
Statement IV: Benzenediazonium chloride is usually dried and stored as a solid for later use.

ChemistryAminesReactions of diazonium saltsHard

Q451Benzenediazonium chloride is treated with each reagent in List I. Match each reagent with the main organic product in List II.

Column I

Column II

P. Warm water

1. Benzene

Q. Hypophosphorous acid (H₃PO₂)

2. p-Hydroxyazobenzene

R. Fluoroboric acid, then heat

3. Phenol

S. Phenol in alkaline solution

4. Fluorobenzene

ChemistryAminesDiazonium salts in synthesisHard

Q452Which sequence converts aniline into 1,3,5-tribromobenzene?

PhysicsAtomsLine spectra of the hydrogen atomEasy

Q453In a hydrogen discharge tube, an electron drops from the n = 3 level to the n = 2 level. What is the energy of the emitted photon? (Eₙ = −13.6/n² eV.)

PhysicsAtomsAlpha-particle scattering and Rutherford's nuclear modelEasy

Q454When a beam of alpha particles is fired at a thin gold foil, most pass almost straight through, but a very small fraction bounce back at angles greater than 90°. What does the rare large-angle scattering show?

PhysicsAtomsEnergy levels of the hydrogen atomMedium

Q455A hydrogen atom is in a state whose total energy is −3.4 eV. What are the kinetic energy and the electrostatic potential energy of its electron in this state?

PhysicsAtomsBohr model of the hydrogen atomMedium

Q456An electron in a hydrogen atom is raised from the ground state (n = 1) to the n = 3 orbit. By what factors do its orbital radius and orbital speed change?

PhysicsAtomsAlpha-particle scattering and Rutherford's nuclear modelMedium

Q457An alpha particle with kinetic energy 5.0 MeV heads directly towards a gold nucleus (Z = 79). How close does it get before stopping momentarily? (Take e²/4πε₀ = 1.44 MeV fm and ignore recoil of the nucleus.)

PhysicsAtomsBohr model of the hydrogen atomMedium

Q458A student tries to use Bohr's formula to predict the spectrum of a neutral helium atom, which has two electrons, and the predictions disagree with experiment. Read the Assertion (A) and Reason (R) and choose the correct option.

Assertion (A): The Bohr model cannot give accurate energy levels for a neutral helium atom.
Reason (R): The Bohr model considers only the attraction between one electron and the nucleus and ignores the repulsion between electrons.

PhysicsAtomsLine spectra of the hydrogen atomMedium

Q459A sample of hydrogen atoms is excited so that every atom reaches the n = 4 level. As the atoms return to the ground state by every possible route, how many different spectral lines can appear, and which transition gives the longest wavelength?

PhysicsAtomsDe Broglie's explanation of Bohr's second postulateHard

Q460Take the radius of the first Bohr orbit of hydrogen as 0.053 nm. Using de Broglie's picture of a standing wave fitting around the orbit, what is the electron's de Broglie wavelength in the n = 3 orbit?

PhysicsAtomsBohr model of the hydrogen atomHard

Q461In the Bohr model of hydrogen, what is the ratio of the electron's frequency of revolution in the n = 2 orbit to that in the n = 1 orbit?

PhysicsAtomsBohr model of the hydrogen atomEasy

Q462Bohr proposed his postulates to rescue the nuclear atom from collapsing. Which of the following claims about an electron in a hydrogen atom agree with those postulates?

I. The electron can occupy only certain orbits, called stationary states.
II. In those orbits its angular momentum is a whole-number multiple of h/2π.
III. While moving in a stationary orbit it radiates energy continuously, because it is accelerating.
IV. It emits a photon of energy hν = Eᵢ − E_f when it jumps from a higher to a lower orbit.

BiologyBiodiversity and ConservationWhat biodiversity isEasy

Q463The term 'biodiversity', meaning the combined variety of life from macromolecules to biomes, was popularised by which sociobiologist?

BiologyBiodiversity and ConservationWhat biodiversity isEasy

Q464Plants of one medicinal species growing in different Himalayan ranges are found to differ in the concentration of the alkaloid they make. This is an example of which level of biodiversity?

BiologyBiodiversity and ConservationThe evil quartetEasy

Q465A large forest is cut by highways and farms into small isolated patches, and many forest-interior animals disappear from the patches. Which cause of biodiversity loss, regarded by NCERT as the most important, does this describe?

BiologyBiodiversity and ConservationSpecies-area relationshipMedium

Q466Two statements about the species-area relationship are given. Select the correct option.

Statement I: When species richness is plotted against area on logarithmic axes, the relationship is a straight line.
Statement II: For comparisons of areas within a single region, the slope Z usually lies between 0.6 and 1.2.

BiologyBiodiversity and ConservationThe evil quartetMedium

Q467Match the concept in Column I with the example or description in Column II, and choose the option with all matches correct.

Column I

Column II

P. Alien species invasion

1. Introduction of a predatory fish into a lake, followed by the loss of more than 200 cichlid species

Q. Co-extinction

2. Loss of an obligately linked species, such as a parasite, when its host disappears

R. Genetic diversity

3. India's more than 50,000 distinct strains of a single cereal crop

S. Ex situ conservation

4. Storing gametes of threatened species at very low temperature

BiologyBiodiversity and ConservationIn situ and ex situ conservationMedium

Q468Which one of the following is an ex situ conservation measure?

BiologyBiodiversity and ConservationPatterns of biodiversityMedium

Q469Read the Assertion and the Reason about the latitudinal gradient of species richness, then choose the correct option.

Assertion (A): Species diversity generally decreases as we move from the equator towards the poles.
Reason (R): Tropical regions receive more solar energy, which contributes to higher productivity and, in turn, indirectly to greater species diversity.

BiologyBiodiversity and ConservationDiversity and stabilityMedium

Q470In long-term plot experiments, ecologist David Tilman found that plots with more species showed which result?

BiologyBiodiversity and ConservationLoss of biodiversityHard

Q471According to the Red List data discussed in NCERT, which of these groups has the highest percentage of its species threatened with extinction?

BiologyBiodiversity and ConservationBiodiversity hotspotsHard

Q472NCERT names three of the world's 34 biodiversity hotspots as covering India's regions of exceptionally high biodiversity. Which option lists these three?

ChemistryBiomoleculesDisaccharidesEasy

Q473Which sugar is non-reducing?

ChemistryBiomoleculesVitaminsEasy

Q474Which vitamin is water-soluble and must therefore be supplied regularly in the diet?

ChemistryBiomoleculesNucleic acidsEasy

Q475Which base is found in RNA but not in DNA?

ChemistryBiomoleculesStructure of glucoseMedium

Q476Glucose forms a pentaacetate on acetylation with acetic anhydride. What does this show about its structure?

ChemistryBiomoleculesRing forms of glucoseMedium

Q477α-D-Glucose and β-D-glucose are called anomers. How do they differ?

ChemistryBiomoleculesProteinsMedium

Q478When an egg is boiled, the albumin coagulates. Which level of protein structure is NOT changed?

ChemistryBiomoleculesRing forms of glucose and fructoseMedium

Q479Fructose is a ketose, yet it is classed as a reducing sugar. Judge the Assertion (A) and the Reason (R) below.

Assertion (A): Fructose reduces Tollens' reagent.
Reason (R): Ketones are always oxidised more easily than aldehydes.

ChemistryBiomoleculesAmino acidsMedium

Q480Amino acids carry both an amino group and a carboxyl group. Which of the statements below are correct?

Statement I: In aqueous solution an amino acid exists mainly as a dipolar ion called a zwitterion.
Statement II: Amino acids are amphoteric, reacting with both acids and bases.
Statement III: Amino acids that the body cannot synthesise are called essential amino acids.
Statement IV: Glycine is optically active.

ChemistryBiomoleculesVitaminsHard

Q481Deficiency of each vitamin listed in List I causes a characteristic disease. Match each vitamin with the deficiency disease in List II.

Column I

Column II

P. Vitamin B₁ (thiamine)

1. Convulsions

Q. Vitamin B₆ (pyridoxine)

2. Increased blood clotting time

R. Vitamin E

3. Beri-beri

S. Vitamin K

4. Increased fragility of red blood cells and muscular weakness

ChemistryBiomoleculesNucleic acidsHard

Q482In a sample of double-stranded DNA, 22% of the bases are guanine. What percentage of the bases are adenine?

BiologyBiotechnology and its ApplicationsGenetically modified crops: Bt cottonEasy

Q483The Bt crystal protein is harmless to Bacillus thuringiensis itself but kills a feeding insect larva. What activates the protein inside the larva?

BiologyBiotechnology and its ApplicationsTissue culture — Meristem cultureEasy

Q484Healthy, virus-free plantlets of crops such as banana and sugarcane can be raised from an infected plant by culturing which plant part?

BiologyBiotechnology and its ApplicationsGene therapyMedium

Q485The first clinical gene therapy, carried out in 1990 on a young girl, was aimed at correcting deficiency of which enzyme?

BiologyBiotechnology and its ApplicationsGenetically engineered insulinMedium

Q486Two statements about production of human insulin by recombinant DNA technology are given. Choose the correct option.

Statement I: In the first recombinant insulin, the A and B chains were produced separately and then joined by disulphide bonds.
Statement II: Mature human insulin retains the C peptide of pro-insulin joining the A and B chains.

BiologyBiotechnology and its ApplicationsRNA interferenceMedium

Q487Study the Assertion and the Reason on engineered resistance to a root parasite in tobacco, then choose the correct option.

Assertion (A): Transgenic tobacco plants making nematode-specific RNA are protected against Meloidogyne incognita.
Reason (R): The RNAs produced in the plant form double-stranded RNA that silences a specific mRNA of the parasite.

BiologyBiotechnology and its ApplicationsApplications of biotechnologyMedium

Q488Match each application or product of biotechnology in Column I with its description in Column II.

Column I

Column II

P. Pomato

1. Somatic hybrid obtained by protoplast fusion

Q. Golden rice

2. Rice enriched with vitamin A

R. Rosie

3. Transgenic cow whose milk contained a human protein

S. ELISA

4. Diagnosis based on antigen-antibody interaction

BiologyBiotechnology and its ApplicationsTransgenic animalsEasy

Q489More than 95 per cent of all transgenic animals produced so far belong to which group?

BiologyBiotechnology and its ApplicationsEthical issues and biopiracyMedium

Q490In India, which organisation set up by the Government decides on the validity of GM research and on the safety of introducing GM organisms for public services?

BiologyBiotechnology and its ApplicationsGene therapyHard

Q491Gene therapy for ADA deficiency using the patient's lymphocytes needs periodic infusions. A permanent cure would require the functional ADA gene to be introduced into:

BiologyBiotechnology and its ApplicationsRNA interferenceHard

Q492Tobacco plants engineered to resist the root-knot nematode make a molecule that stops the parasite from surviving in the roots. What is that molecule?

BiologyBiotechnology: Principles and ProcessesRestriction enzymesEasy

Q493In the name EcoRI of a restriction enzyme, what does the letter R represent?

BiologyBiotechnology: Principles and ProcessesGel electrophoresisEasy

Q494In agarose gel electrophoresis of a DNA digest, towards which electrode do the fragments move, and which fragments travel farthest from the well?

BiologyBiotechnology: Principles and ProcessesPolymerase chain reactionEasy

Q495Which feature of the DNA polymerase used in PCR makes it suitable, and from which organism is it isolated?

BiologyBiotechnology: Principles and ProcessesRestriction enzymesMedium

Q496Two statements about restriction enzymes are given. Select the correct option.

Statement I: Cutting the two strands at positions slightly away from the centre of a palindromic site leaves single-stranded sticky ends.
Statement II: Exonucleases cut DNA at specific internal recognition sites.

BiologyBiotechnology: Principles and ProcessesCloning vectorsMedium

Q497Read the Assertion and the Reason about selecting recombinants with a plasmid vector in which foreign DNA is inserted at the BamH I site, then choose the correct option.

Assertion (A): Host cells carrying the recombinant plasmid fail to grow on tetracycline but grow on ampicillin.
Reason (R): The insert at the BamH I site inactivates the tetracycline resistance gene.

BiologyBiotechnology: Principles and ProcessesIsolation of the genetic materialMedium

Q498Match each agent used while isolating DNA in Column I with its specific use in Column II.

Column I

Column II

P. Lysozyme

1. Breaks plant cells

Q. Cellulase

2. Breaks bacterial cells

R. Chitinase

3. Breaks fungal cells

S. Ribonuclease

4. Removes RNA from the preparation

BiologyBiotechnology: Principles and ProcessesCloning vectorsMedium

Q499In a vector with a coloured-colony selection system based on β-galactosidase, a colourless colony on a chromogenic substrate indicates:

BiologyBiotechnology: Principles and ProcessesIntroducing DNA into the hostMedium

Q500Which sequence correctly describes making bacterial cells take up a recombinant plasmid by the usual chemical method?

BiologyBiotechnology: Principles and ProcessesPolymerase chain reactionHard

Q501Each PCR cycle doubles the number of copies of the target DNA. Starting from a single copy, about how many copies exist after 30 cycles?

BiologyBiotechnology: Principles and ProcessesRestriction enzymesHard

Q502A recognition site is palindromic if the 5'→3' sequence of one strand equals the 5'→3' sequence of its complementary strand. Which 6-base-pair site is palindromic in this sense?

ChemistryChemical KineticsMolecularity of a reactionEasy

Q503Which statement about the molecularity of a reaction is correct?

ChemistryChemical KineticsRate of a chemical reactionEasy

Q504For 2N₂O₅(g) → 4NO₂(g) + O₂(g), N₂O₅ is consumed at 0.020 mol L⁻¹ s⁻¹ at a certain moment. At what rate is NO₂ being formed at that moment?

ChemistryChemical KineticsOrder of a reactionEasy

Q505The rate law of a reaction is rate = k[A][B], with concentrations in mol L⁻¹ and time in seconds. What are the units of k?

ChemistryChemical KineticsZero order reactionsMedium

Q506A reaction is zero order in its only reactant, with k = 0.010 mol L⁻¹ s⁻¹. If the initial concentration is 0.50 mol L⁻¹, what is its half-life?

ChemistryChemical KineticsRate law and rate constantMedium

Q507For A + B → products, initial rates were measured at 298 K: Run 1: [A] = 0.10 M, [B] = 0.10 M, rate = 2.0 × 10⁻³ M s⁻¹ Run 2: [A] = 0.20 M, [B] = 0.10 M, rate = 8.0 × 10⁻³ M s⁻¹ Run 3: [A] = 0.10 M, [B] = 0.20 M, rate = 4.0 × 10⁻³ M s⁻¹ What is the rate law?

ChemistryChemical KineticsOrder of a reaction and pseudo first orderMedium

Q508Match each type of reaction in List I with an example of it in List II.

Column I

Column II

P. Zero order reaction

1. Acid hydrolysis of ethyl acetate in a large excess of water

Q. First order reaction

2. Decomposition of NH₃ on a hot platinum surface at high pressure

R. Pseudo first order reaction

3. Decay of a radioactive nucleus

S. Termolecular elementary reaction

4. 2NO(g) + O₂(g) → 2NO₂(g)

ChemistryChemical KineticsEffect of catalystMedium

Q509A catalyst is added to a reversible reaction at constant temperature. Which of the statements below are correct?

Statement I: The catalyst lowers the activation energy of the reaction.
Statement II: The Gibbs energy change of the reaction is unaffected by the catalyst.
Statement III: The catalyst increases the equilibrium constant of the forward reaction.
Statement IV: The catalyst provides an alternative pathway, often through a temporary intermediate.

ChemistryChemical KineticsTemperature dependence of rateMedium

Q510Most reactions speed up noticeably when they are warmed. Judge the Assertion (A) and the Reason (R) below.

Assertion (A): For many chemical reactions the rate constant nearly doubles for a 10 K rise in temperature.
Reason (R): A rise in temperature increases the fraction of molecules whose kinetic energy equals or exceeds the activation energy.

ChemistryChemical KineticsArrhenius equationHard

Q511The rate constant of a reaction triples when the temperature is raised from 300 K to 320 K. What is its activation energy? (R = 8.314 J K⁻¹ mol⁻¹, log 3 = 0.477)

ChemistryChemical KineticsIntegrated rate equation: first orderHard

Q512A first-order reaction is 20% complete in 10 minutes. What is its half-life? (log 1.25 = 0.0969)

ChemistryCoordination CompoundsNomenclature of coordination compoundsEasy

Q513What is the IUPAC name of K₃[Fe(CN)₆]?

ChemistryCoordination CompoundsLigands and denticityEasy

Q514Which ligand is ambidentate?

ChemistryCoordination CompoundsWerner's theoryEasy

Q515One mole of a complex with empirical formula CrCl₃·5H₂O gives two moles of AgCl when treated with excess AgNO₃ solution. Assuming a coordination number of 6, what is its formula?

ChemistryCoordination CompoundsCrystal field theoryMedium

Q516How many unpaired electrons are present in the octahedral complex ion [Fe(CN)₆]³⁻? (CN⁻ is a strong-field ligand.)

ChemistryCoordination CompoundsValence bond theoryMedium

Q517According to valence bond theory, which description fits [Ni(CN)₄]²⁻?

ChemistryCoordination CompoundsOptical isomerismMedium

Q518Which complex ion is optically active?

ChemistryCoordination CompoundsColour in coordination compoundsMedium

Q519Aqueous solutions of many titanium(III) salts have a characteristic colour. Judge the Assertion (A) and the Reason (R) below.

Assertion (A): The complex [Ti(H₂O)₆]³⁺ is violet.
Reason (R): [Ti(H₂O)₆]³⁺ absorbs light in the blue-green region, which promotes its single d electron from a t₂g to an e_g orbital.

ChemistryCoordination CompoundsBonding in metal carbonylsMedium

Q520Metal carbonyls contain only carbon monoxide as ligand. Which of the statements below are correct?

Statement I: Ni(CO)₄ is tetrahedral.
Statement II: Fe(CO)₅ is trigonal bipyramidal.
Statement III: The metal–carbon bond in a metal carbonyl has both σ and π character.
Statement IV: Cr(CO)₆ is square planar.

ChemistryCoordination CompoundsStructural isomerismHard

Q521Each pair in List I is a pair of structural isomers. Match each pair with its type of isomerism in List II.

Column I

Column II

P. [Co(NH₃)₄(NO₂)Cl]Cl and [Co(NH₃)₄(ONO)Cl]Cl

1. Ionisation isomerism

Q. [Cu(NH₃)₄][PtCl₄] and [Pt(NH₃)₄][CuCl₄]

2. Hydrate (solvate) isomerism

R. [Pt(NH₃)₄Cl₂]Br₂ and [Pt(NH₃)₄Br₂]Cl₂

3. Linkage isomerism

S. [Cr(H₂O)₄Cl₂]Cl·2H₂O and [Cr(H₂O)₅Cl]Cl₂·H₂O

4. Coordination isomerism

ChemistryCoordination CompoundsCrystal field theoryHard

Q522[Co(NH₃)₆]³⁺ is a low-spin octahedral complex. Ignoring pairing energy, what is its crystal field stabilisation energy (CFSE)?

PhysicsCurrent ElectricityDrift of electrons and the origin of resistivityEasy

Q523A copper wire of uniform cross-sectional area 2.5 mm² carries a steady current of 4.0 A. The number density of free electrons in copper is 8.0 × 10²⁸ m⁻³ and the electronic charge is 1.6 × 10⁻¹⁹ C. What is the drift speed of the free electrons?

PhysicsCurrent ElectricityOhm's law and resistivityEasy

Q524A uniform metal wire has a resistance of 8.0 Ω. It is drawn out uniformly so that its length becomes 25% greater than before, with its volume and resistivity unchanged. What is its new resistance?

PhysicsCurrent ElectricityTemperature dependence of resistivityEasy

Q525A coil of metal wire has a resistance of 20.0 Ω at 20 °C. The temperature coefficient of resistivity of the metal (taking 20 °C as the reference temperature) is 4.0 × 10⁻³ °C⁻¹. Neglecting thermal expansion of the wire, what is the resistance of the coil at 70 °C?

PhysicsCurrent ElectricityCells, emf, internal resistanceMedium

Q526A cell of unknown emf E and internal resistance r is connected in series with an ideal ammeter and a 5.0 Ω resistor; the ammeter reads 0.50 A. The 5.0 Ω resistor is then replaced by an 11.0 Ω resistor (nothing else changes) and the ammeter reads 0.25 A. What are E and r?

PhysicsCurrent ElectricityWheatstone bridgeMedium

Q527Four resistors are joined to form a closed quadrilateral ABCD: 2 Ω between A and B, 4 Ω between B and C, 6 Ω between C and D, and 3 Ω between D and A. A fifth resistor of 5 Ω is connected directly between B and D. What is the equivalent resistance of the network between terminals A and C?

PhysicsCurrent ElectricityCells in series and in parallelHard

Q528Two cells are connected in parallel: their positive terminals are joined to one junction and their negative terminals to another. Cell 1 has emf 6.0 V and internal resistance 1.0 Ω; cell 2 has emf 4.0 V and internal resistance 2.0 Ω. A 4.0 Ω resistor is connected between the two junctions. What is the current through the 4.0 Ω resistor?

PhysicsCurrent ElectricityElectrical energy, powerMedium

Q529Bulb P is rated 100 W, 200 V and bulb Q is rated 25 W, 200 V. The two bulbs are connected in series across a 200 V supply. Assuming each bulb's resistance stays equal to its value at rated operation, what power is dissipated in bulb Q?

PhysicsCurrent ElectricityElectric currents in conductorsMedium

Q530Read the Assertion (A) and Reason (R) about a copper wire whose cross-section tapers steadily from 2 mm² at one end to 1 mm² at the other end, carrying a steady current. Choose the correct option.

Assertion (A): The drift speed of the free electrons at the 1 mm² end is twice their drift speed at the 2 mm² end.
Reason (R): In steady state the same current I crosses every cross-section of the wire, and I = neAv_d with the free-electron density n the same throughout the copper.

PhysicsCurrent ElectricityKirchhoff's rulesHard

Q531An ideal 12 V battery (no internal resistance) has its positive terminal connected to junction A and its negative terminal to junction C. Two branches join A to C: branch 1 runs A → B → C with 2.0 Ω between A and B and 4.0 Ω between B and C; branch 2 runs A → D → C with 4.0 Ω between A and D and 2.0 Ω between D and C. A 2.0 Ω resistor is connected directly between junctions B and D. What is the current in the B–D resistor?

PhysicsDual Nature of Radiation and MatterParticle nature of light: the photonEasy

Q532A green laser pointer emits light of wavelength 500 nm. What is the energy of one photon of this light, in electronvolts? (Take hc = 1240 eV nm.)

PhysicsDual Nature of Radiation and MatterEffect of intensity on photocurrentEasy

Q533Monochromatic light above the threshold frequency falls on a photocell. The intensity is doubled while the frequency is kept the same. What happens to the saturation current and to the stopping potential?

PhysicsDual Nature of Radiation and MatterEinstein's photoelectric equationMedium

Q534Light of wavelength 400 nm falls on a metal surface whose work function is 2.3 eV. What is the stopping potential for the emitted photoelectrons? (Take hc = 1240 eV nm.)

PhysicsDual Nature of Radiation and MatterParticle nature of light: the photonMedium

Q535A red laser of wavelength 660 nm delivers a beam of power 3.0 mW. About how many photons does it emit per second? (h = 6.63 × 10⁻³⁴ J s, c = 3.0 × 10⁸ m s⁻¹.)

PhysicsDual Nature of Radiation and MatterWave nature of matterMedium

Q536An electron and a proton are each accelerated until they have the same kinetic energy. Roughly what is the ratio of the electron's de Broglie wavelength to the proton's? (mₚ/mₑ ≈ 1836.)

PhysicsDual Nature of Radiation and MatterEinstein's photoelectric equationHard

Q537A student measures the stopping potential for one metal at two frequencies: 1.2 V at 8.0 × 10¹⁴ Hz and 2.0 V at 1.0 × 10¹⁵ Hz. Using only these two readings, what is the work function of the metal?

PhysicsDual Nature of Radiation and MatterParticle nature of light: the photonMedium

Q538A beam of monochromatic ultraviolet light is passed through a region with a strong electric field and then into a gas. Which of these statements about its photons are correct?

I. All photons in the beam carry the same energy.
II. The photons are deflected by the electric field because they carry charge.
III. The total number of photons is conserved when the beam is absorbed by the gas.
IV. Each photon carries momentum hν/c.

PhysicsDual Nature of Radiation and MatterPhotoelectric effect and wave theory of lightMedium

Q539A photocell is lit by extremely faint light above its threshold frequency, and a current starts to flow at once. Read the Assertion (A) and Reason (R) and choose the correct option.

Assertion (A): Photoelectrons appear with no measurable delay, even when the light is very dim.
Reason (R): Light energy arrives in discrete photons, and a single photon can give its whole energy hν to one electron at once.

PhysicsDual Nature of Radiation and MatterWave nature of matterHard

Q540For an electron-diffraction experiment, electrons must have a de Broglie wavelength of 0.20 nm. What kinetic energy must each electron have? (For electrons, λ = 1.227/√V nm, with V in volts.)

PhysicsDual Nature of Radiation and MatterElectron emissionEasy

Q541Match each item in List I with what supplies or describes it in List II.

Column I

Column II

P. Thermionic emission

1. Light of frequency above the threshold

Q. Field emission

2. h/e

R. Photoelectric emission

3. Heating the metal

S. Slope of the stopping potential versus frequency graph

4. A very strong electric field (about 10⁸ V m⁻¹)

BiologyEcosystemProductivityEasy

Q542In a grassland, the producers fix 1200 g m⁻² yr⁻¹ of organic matter as gross primary productivity, and 400 g m⁻² yr⁻¹ is used in the producers' own respiration. What is the net primary productivity?

BiologyEcosystemEcological pyramidsEasy

Q543Which type of ecological pyramid is always upright in every ecosystem?

BiologyEcosystemFood chains and food websEasy

Q544Which statement about the major route of energy flow is correct?

BiologyEcosystemDecompositionMedium

Q545Statements I and II below concern the rate and products of decomposition of detritus in an ecosystem. Which of the options is correct?

Statement I: Humus is highly resistant to microbial action and undergoes decomposition at an extremely slow rate.
Statement II: Detritus rich in lignin decomposes faster than detritus rich in nitrogen and water-soluble sugars.

BiologyEcosystemEcological pyramidsMedium

Q546Read the Assertion and the Reason about biomass pyramids in a sea and choose the correct option.

Assertion (A): The pyramid of biomass in a sea is generally inverted.
Reason (R): The standing crop of phytoplankton at any time is small compared with the biomass of the zooplankton and fishes it supports.

BiologyEcosystemDecompositionMedium

Q547Match the step of decomposition in Column I with the process in Column II.

Column I

Column II

P. Fragmentation

1. Enzymatic degradation of detritus into simpler substances

Q. Leaching

2. Breaking of detritus into smaller particles by detritivores

R. Catabolism

3. Movement of water-soluble inorganic nutrients into deeper soil layers

S. Humification

4. Formation of dark, resistant amorphous matter

BiologyEcosystemTrophic levels and the 10 per cent lawMedium

Q548In the food chain grass → grasshopper → frog → snake, the grass fixes 5000 kJ of energy. Using the 10 per cent law, how much energy reaches the snake?

BiologyEcosystemProductivityMedium

Q549What fraction of the incident solar radiation is photosynthetically active radiation (PAR)?

BiologyEcosystemProductivityHard

Q550In a forest the net primary productivity is 900 g m⁻² yr⁻¹, and the producers' respiration uses 40 per cent of their gross primary productivity. What is the gross primary productivity?

BiologyEcosystemProductivityHard

Q551The biosphere's annual net primary productivity is about 170 billion tons (dry weight), of which the oceans, which cover about 70 per cent of the earth's surface, contribute about 55 billion tons. Roughly what share of global NPP is oceanic?

PhysicsElectric Charges and FieldsBasic properties of electric chargeEasy

Q552A plastic comb, initially neutral, is run through dry hair and ends up with a charge of −4.8 μC. Taking e = 1.6 × 10⁻¹⁹ C, how many electrons did the comb gain?

PhysicsElectric Charges and FieldsCoulomb's lawEasy

Q553Two small charged spheres in air repel each other with a force F. The charge on each sphere is doubled and the distance between their centres is made three times as large. What is the new force?

PhysicsElectric Charges and FieldsElectric fieldMedium

Q554Point charges of +2 μC and +8 μC are fixed 30 cm apart in air. At which point on the line joining them is the net electric field zero?

PhysicsElectric Charges and FieldsElectric dipoleMedium

Q555A short electric dipole produces a field of magnitude E at a point on its axis at distance r from its centre. What is the field at a point on its equatorial line at distance 2r from its centre (r much larger than the dipole length)?

PhysicsElectric Charges and FieldsElectric field linesMedium

Q556A student draws the field-line pattern for a pair of point charges and writes four rules beside it. Which of the rules are correct?

I. Two field lines can never cross each other.
II. Electrostatic field lines can form closed loops.
III. Field lines start on positive charges and end on negative charges, or go to or come from infinity.
IV. Where field lines are farther apart, the field is stronger.

PhysicsElectric Charges and FieldsGauss's lawMedium

Q557A closed surface encloses point charges of +3 μC and −5 μC. A third charge of +4 μC lies just outside the surface. Taking ε₀ = 8.854 × 10⁻¹² C² N⁻¹ m⁻², what is the net electric flux out of the closed surface?

PhysicsElectric Charges and FieldsApplications of Gauss's lawEasy

Q558A very large, thin, flat non-conducting sheet carries a uniform surface charge density σ = 8.85 × 10⁻⁹ C m⁻². What are the magnitudes of the electric field at points 2 cm and 4 cm from the sheet, near its middle? (ε₀ = 8.85 × 10⁻¹² C² N⁻¹ m⁻²)

PhysicsElectric Charges and FieldsElectric fieldHard

Q559Charges +q, +q and −q are placed at the three corners of an equilateral triangle of side a. Using k = 1/(4πε₀), what is the magnitude and direction of the electric field at the centroid of the triangle?

PhysicsElectric Charges and FieldsDipole in a uniform external fieldMedium

Q560An electric dipole sits in a uniform electric field with its moment tilted at an angle to the field. Read the Assertion (A) and Reason (R) about it and choose the correct option.

Assertion (A): An electric dipole placed in a uniform electric field, with its moment at an angle to the field, experiences no net force but does experience a torque.
Reason (R): The forces qE and −qE on the two charges are equal and opposite, but they act at different points, forming a couple.

PhysicsElectric Charges and FieldsDipole in a non-uniform fieldHard

Q561A small electric dipole is held at some distance from a fixed point charge +Q, with its dipole moment pointing directly away from Q (that is, along the field of Q). The dipole is then released. What does it experience at the instant of release?

ChemistryElectrochemistryGalvanic cellsEasy

Q562In a working Daniell cell, Zn(s)|Zn²⁺(aq)||Cu²⁺(aq)|Cu(s), which statement is correct?

ChemistryElectrochemistryVariation of conductivity with concentrationEasy

Q563An aqueous KCl solution is diluted step by step. How do its conductivity (κ) and molar conductivity (Λm) change?

ChemistryElectrochemistryBatteriesEasy

Q564A car battery and a watch battery work on different chemistry. Which of the statements below are correct?

Statement I: When a lead storage battery discharges, PbSO₄ forms at both electrodes.
Statement II: In a lead storage battery the anode is lead and the cathode is a lead grid packed with PbO₂.
Statement III: The concentration of sulphuric acid in a lead storage battery rises during discharge.
Statement IV: A mercury cell gives a nearly constant potential of about 1.35 V over its life.

ChemistryElectrochemistryCell potential and Gibbs energyMedium

Q565For the cell Zn(s)|Zn²⁺(aq, 1 M)||Ag⁺(aq, 1 M)|Ag(s), E°(Zn²⁺/Zn) = −0.76 V and E°(Ag⁺/Ag) = +0.80 V. What is ΔrG° for the cell reaction Zn + 2Ag⁺ → Zn²⁺ + 2Ag? (F = 96 487 C mol⁻¹)

ChemistryElectrochemistryNernst equationMedium

Q566A Daniell cell is set up with [Zn²⁺] = 0.010 M and [Cu²⁺] = 1.0 M at 298 K. E°cell = 1.10 V. What is the cell potential? (2.303RT/F = 0.059 V)

ChemistryElectrochemistryQuantitative aspects of electrolysisMedium

Q567A current of 2.0 A is passed for 965 s through aqueous CuSO₄ using inert electrodes. What mass of copper is deposited at the cathode? (Cu = 63.5 g mol⁻¹, F = 96 500 C mol⁻¹)

ChemistryElectrochemistryProducts of electrolysisMedium

Q568The products of electrolysis depend on the electrolyte, its state and the electrodes. Match each electrolysis in List I with an observation in List II.

Column I

Column II

P. Aqueous NaCl, inert electrodes

1. Copper dissolves at the anode and deposits at the cathode

Q. Molten NaCl, inert electrodes

2. Sodium metal forms at the cathode

R. Dilute H₂SO₄, platinum electrodes

3. Oxygen is evolved at the anode

S. Aqueous CuSO₄, copper electrodes

4. Hydrogen at the cathode and chlorine at the anode

ChemistryElectrochemistryMolar conductivity of weak electrolytesMedium

Q569Acetic acid and KCl behave very differently when their solutions are diluted. Judge the Assertion (A) and the Reason (R) below.

Assertion (A): The molar conductivity of acetic acid increases steeply as its solution approaches infinite dilution.
Reason (R): On dilution the degree of dissociation of a weak electrolyte increases, producing more ions per mole.

ChemistryElectrochemistryMeasurement of conductivityHard

Q570A conductivity cell with cell constant 1.5 cm⁻¹ is filled with a 0.050 M solution of an electrolyte, and its resistance is 300 Ω. What is the molar conductivity of the solution, in S cm² mol⁻¹?

ChemistryElectrochemistryKohlrausch's law and degree of dissociationHard

Q571A 0.010 M solution of a weak monobasic acid HA has Λm = 39.0 S cm² mol⁻¹. Its limiting molar conductivity, found from Kohlrausch's law, is Λ°m = 390 S cm² mol⁻¹. What is the dissociation constant Ka of HA?

PhysicsElectromagnetic InductionFaraday's law of inductionEasy

Q572A flat coil of 200 turns, each of area 0.050 m², lies with its plane perpendicular to a uniform magnetic field. The field rises steadily from 0.10 T to 0.50 T in 0.20 s. What is the magnitude of the induced emf?

PhysicsElectromagnetic InductionLenz's law and conservation of energyEasy

Q573The N pole of a bar magnet is pushed towards a closed circular wire loop along the loop's axis. As seen from the magnet's side, what is the direction of the induced current in the loop?

PhysicsElectromagnetic InductionMotional emfMedium

Q574A metal rod of length 0.50 m slides at a constant 4.0 m s⁻¹ along two frictionless horizontal rails joined by a 2.0 Ω resistor. A uniform field of 0.30 T acts vertically. Neglecting the resistance of the rod and rails, what external force is needed to keep the rod moving at constant speed?

PhysicsElectromagnetic InductionRotating rods and wheelsMedium

Q575A metal rod of length 0.80 m rotates at 10 revolutions per second about an axis through one end, perpendicular to the rod. A uniform field of 0.50 T is parallel to the axis of rotation. What emf is developed between the ends of the rod?

PhysicsElectromagnetic InductionSelf-inductance and magnetic energyMedium

Q576An air-cored solenoid 40 cm long has 400 turns and a cross-sectional area of 5.0 cm². How much magnetic energy is stored in it when it carries a steady current of 3.0 A? (μ₀ = 4π × 10⁻⁷ T m A⁻¹)

PhysicsElectromagnetic InductionMutual inductanceMedium

Q577A coil-design worksheet lists four claims about self and mutual inductance. Pick the option that names every correct claim.

I. The SI unit of inductance, the henry, equals one weber per ampere.
II. For two long coaxial solenoids, the mutual inductance of the first with respect to the second equals that of the second with respect to the first.
III. The self-induced emf in a coil opposes a rise in current but does not oppose a fall in current.
IV. Inserting a soft-iron core into a solenoid increases its self-inductance.

PhysicsElectromagnetic InductionAC generatorHard

Q578A coil of 100 turns, each of area 0.020 m², rotates at 50 revolutions per second about an axis perpendicular to a uniform field of 0.10 T. What is the instantaneous emf at the moment the plane of the coil makes an angle of 30° with the field?

PhysicsElectromagnetic InductionLenz's law and conservation of energyMedium

Q579A bar magnet is dropped, N pole first, along the axis of a fixed horizontal copper ring. Read the Assertion (A) and Reason (R) and choose the correct option.

Assertion (A): While the magnet is above the ring and approaching it, its acceleration is less than g.
Reason (R): The current induced in the ring opposes the change in magnetic flux that produces it.

PhysicsElectromagnetic InductionMagnetic fluxHard

Q580A coil of 50 turns, each of area 0.010 m², has total resistance 4.0 Ω and is connected in a closed circuit. It lies with its plane perpendicular to a uniform field of 0.40 T and is flipped through 180° about a diameter in 0.10 s. How much charge flows through the circuit during the flip?

PhysicsElectromagnetic InductionFaraday's law of inductionEasy

Q581Match each expression in List I with what it gives in List II.

Column I

Column II

P. −N dΦ/dt

1. Energy stored in an inductor carrying a current

Q. Blv

2. Emf across a straight rod moving at right angles to a field

R. ½LI²

3. Peak emf of a coil rotating in a uniform field

S. NBAω

4. Emf induced in a coil by a changing flux

PhysicsElectromagnetic WavesNature of electromagnetic wavesEasy

Q582In a plane electromagnetic wave travelling in vacuum, the electric field oscillates with amplitude 120 V m⁻¹. What are the amplitude of the magnetic field and its phase relative to the electric field? (c = 3 × 10⁸ m s⁻¹)

PhysicsElectromagnetic WavesThe electromagnetic spectrumEasy

Q583Which sequence lists these radiations in order of increasing wavelength?

PhysicsElectromagnetic WavesDisplacement currentMedium

Q584While a parallel plate capacitor with plates of area 0.040 m² is being charged, the electric field between the plates increases at a rate of 2.0 × 10¹² V m⁻¹ s⁻¹. What is the displacement current between the plates? (ε₀ = 8.85 × 10⁻¹² C² N⁻¹ m⁻²; ignore fringing)

PhysicsElectromagnetic WavesSpeed in vacuum and in mediaMedium

Q585The electric field of an em wave in vacuum is E_y = E₀ sin(kx − ωt), with ω = 6.0 × 10⁹ rad s⁻¹. What is its wavelength? (c = 3.0 × 10⁸ m s⁻¹)

PhysicsElectromagnetic WavesNature of electromagnetic wavesEasy

Q586A plane em wave travels in the +z direction. At a certain point and instant, its electric field points along +x. Along which direction does its magnetic field point at that point and instant?

PhysicsElectromagnetic WavesThe electromagnetic spectrumMedium

Q587Match each band of the electromagnetic spectrum in List I with a matching fact about it in List II.

Column I

Column II

P. Microwaves

1. Produced when high-energy electrons strike a metal target

Q. Infrared

2. Largely absorbed by the ozone layer in the upper atmosphere

R. Ultraviolet

3. Produced by klystrons, magnetrons and Gunn diodes; used in radar

S. X-rays

4. Used in TV remote controls and in physical therapy

PhysicsElectromagnetic WavesSources of electromagnetic wavesMedium

Q588Four claims are made about how electromagnetic waves are produced and how they travel. Which of them hold?

I. Electromagnetic waves carry energy from one place to another.
II. An accelerated charge radiates em waves, but a charge moving with constant velocity does not.
III. In vacuum, higher-frequency em waves travel faster than lower-frequency ones.
IV. Electromagnetic waves need a material medium to travel.

PhysicsElectromagnetic WavesSpeed in vacuum and in mediaHard

Q589A 100 MHz em wave passes from vacuum into a non-magnetic medium (μᵣ = 1) of relative permittivity εᵣ = 2.25. What is its wavelength in the medium? (c = 3.0 × 10⁸ m s⁻¹)

PhysicsElectromagnetic WavesThe charging capacitor puzzleMedium

Q590A parallel plate capacitor is being charged by a steady current. Read the Assertion (A) and Reason (R) and choose the correct option.

Assertion (A): A magnetic field exists in the region between the plates, even though no charge flows across the gap.
Reason (R): The electric flux between the plates is changing, and a changing electric flux produces a magnetic field just as a conduction current does.

PhysicsElectromagnetic WavesNature of electromagnetic wavesHard

Q591The magnetic field of an em wave in vacuum is B_z = (4.0 × 10⁻⁸ T) sin(1000x + 3.0 × 10¹¹ t), with x in metres and t in seconds. In which direction does the wave travel, and what is the amplitude of its electric field? (c = 3.0 × 10⁸ m s⁻¹)

PhysicsElectrostatic Potential and CapacitancePotential due to a system of chargesEasy

Q592Point charges of +4 nC and −6 nC are fixed 20 cm apart in air. What is the electric potential at the midpoint of the line joining them? (k = 9 × 10⁹ N m² C⁻²)

PhysicsElectrostatic Potential and CapacitanceElectrostatic potentialEasy

Q593A charge of +3 μC is moved slowly (no change in kinetic energy) from a point A at a potential of 20 V to a point B at a potential of 80 V. How much work must an external agent do?

PhysicsElectrostatic Potential and CapacitanceElectrostatics of conductorsMedium

Q594A charged metal body is in electrostatic equilibrium. Which of the following statements about it are correct?

I. The electric field everywhere inside the metal is zero.
II. The electric potential everywhere inside the metal is zero.
III. Just outside the surface, the field is normal to the surface and equals σ/ε₀, where σ is the local surface charge density.
IV. Any excess charge resides on the surface.

PhysicsElectrostatic Potential and CapacitancePotential energy of a system of chargesMedium

Q595Charges of +1 μC, +2 μC and −3 μC are placed at the corners of an equilateral triangle of side 30 cm in air. What is the electrostatic potential energy of the system? (k = 9 × 10⁹ N m² C⁻²)

PhysicsElectrostatic Potential and CapacitanceEffect of dielectric on capacitanceMedium

Q596A parallel plate capacitor is charged by a battery to charge Q₀ and stored energy U₀. The battery is then disconnected, and a slab of dielectric constant K = 4 is inserted to fill the gap completely. What are the new charge and stored energy?

PhysicsElectrostatic Potential and CapacitanceCombination of capacitorsMedium

Q597Capacitors of 2 μF and 3 μF are connected in parallel, and this pair is connected in series with a 5 μF capacitor. The combination is connected across a 100 V supply. What is the charge on the 3 μF capacitor?

PhysicsElectrostatic Potential and CapacitanceEnergy stored in a capacitorHard

Q598A 4 μF capacitor charged to 50 V is disconnected from its supply and connected across an uncharged 6 μF capacitor (positive plate to one plate, negative plate to the other). How much electrostatic energy is lost when the charges settle?

PhysicsElectrostatic Potential and CapacitanceEquipotential surfacesMedium

Q599A small test charge is carried around a circle centred on an isolated point charge. Read the Assertion (A) and Reason (R) about this and choose the correct option.

Assertion (A): No work is done by the electric field on the test charge as it moves along the circle.
Reason (R): The electric field at every point is perpendicular to the equipotential surface through that point.

PhysicsElectrostatic Potential and CapacitancePotential energy in an external fieldHard

Q600An electric dipole of moment 4.0 × 10⁻⁹ C m is in stable equilibrium in a uniform field of 2.0 × 10⁵ N C⁻¹. How much work must an external agent do to rotate it slowly until its moment makes 120° with the field?

PhysicsElectrostatic Potential and CapacitancePotential due to a dipoleEasy

Q601Match each quantity in List I with how it depends on the distance r from the source in List II (for the dipole, r is much larger than its length).

Column I

Column II

P. Potential of a point charge

1. ∝ 1/r

Q. Field of a short dipole

2. ∝ 1/r²

R. Potential inside a charged spherical conducting shell

3. ∝ 1/r³

S. Potential of a short dipole at a point on its axis

4. Independent of r

BiologyEvolutionChemical evolution and the first lifeEasy

Q602In the laboratory simulation of early earth conditions carried out in 1953, an electric discharge was passed through a closed flask. Which mixture of gases was present at 800°C?

BiologyEvolutionHomology and analogyEasy

Q603Which of the following pairs of structures is an example of homology (divergent evolution)?

BiologyEvolutionAdaptive radiationEasy

Q604The different beak shapes of finches on the Galapagos islands, all arising from one ancestral seed-eating form, illustrate:

BiologyEvolutionHardy-Weinberg principleMedium

Q605Statements I and II below concern the Hardy-Weinberg principle for a gene with two alleles. Choose the correct option.

Statement I: In a population in Hardy-Weinberg equilibrium, the frequency of heterozygotes is 2pq.
Statement II: Strong gene flow into a population leaves its allele frequencies unchanged.

BiologyEvolutionNatural selection in actionMedium

Q606Read the Assertion and the Reason about the moth populations observed in industrial England, and choose the correct option.

Assertion (A): After industrialisation, the proportion of dark-winged moths rose in polluted regions of England.
Reason (R): Pollution killed the lichens and darkened tree trunks, so dark moths were better camouflaged against predators.

BiologyEvolutionMutation and selectionMedium

Q607Match the process in Column I with its effect in Column II.

Column I

Column II

P. Stabilising selection

1. Individuals with the mean trait value are favoured, narrowing the distribution

Q. Directional selection

2. Individuals at one extreme are favoured, shifting the mean to that side

R. Disruptive selection

3. Individuals at both extremes are favoured, giving two peaks

S. Genetic drift

4. Random change in allele frequency, especially in small populations

BiologyEvolutionHardy-Weinberg principleMedium

Q608In a large randomly mating population in Hardy-Weinberg equilibrium, 9 per cent of individuals show a recessive trait (genotype aa). What is the expected frequency of heterozygous individuals?

BiologyEvolutionOrigin and evolution of manMedium

Q609Which option arranges the human ancestors in increasing order of cranial capacity?

BiologyEvolutionOrigin and evolution of manHard

Q610Which of the following pairings of a fossil primate or hominid with a feature is correct?

BiologyEvolutionHardy-Weinberg principleHard

Q611Which one of the following is NOT among the factors that NCERT lists as disturbing Hardy-Weinberg (genetic) equilibrium?

ChemistryHaloalkanes and HaloarenesSN2 mechanismEasy

Q612Which bromide reacts fastest with NaI in acetone by the SN2 mechanism?

ChemistryHaloalkanes and HaloarenesPreparation of haloalkanesEasy

Q613Heating CH₃Br with AgF gives CH₃F. What is this reaction called?

ChemistryHaloalkanes and HaloarenesReactions of haloarenesEasy

Q614Why does chlorobenzene undergo nucleophilic substitution far less readily than chloroethane?

ChemistryHaloalkanes and HaloarenesSN1 mechanismMedium

Q615Arrange these chlorides in order of DECREASING reactivity by the SN1 mechanism: (I) C₆H₅CH₂Cl, (II) CH₃CH₂CH₂Cl, (III) (CH₃)₂CHCl, (IV) C₆H₅C(CH₃)₂Cl.

ChemistryHaloalkanes and HaloarenesElimination reactionsMedium

Q6162-Bromopentane is heated with alcoholic KOH. What is the major product?

ChemistryHaloalkanes and HaloarenesReactions with metalsMedium

Q617Ethylmagnesium bromide is prepared from bromoethane and magnesium in dry ether. If a little water is added to it, what forms?

ChemistryHaloalkanes and HaloarenesStereochemistry of substitutionMedium

Q618Optically active (R)-2-bromobutane is treated with hydroxide ion under conditions that favour the SN2 mechanism. Judge the Assertion (A) and the Reason (R) below.

Assertion (A): The butan-2-ol formed has the inverted configuration.
Reason (R): In SN2, the nucleophile attacks from the side opposite the leaving group, and as the new bond forms the other three groups on that carbon swing over to the other side.

ChemistryHaloalkanes and HaloarenesPolyhalogen compoundsMedium

Q619Several polyhalogen compounds were once widely used but are now restricted. Which of the statements below about them are correct?

Statement I: Chloroform is slowly oxidised by air in the presence of light to a poisonous gas, phosgene.
Statement II: Carbon tetrachloride released into the air helps rebuild the ozone layer.
Statement III: DDT is not metabolised quickly by animals and builds up in their fatty tissue.
Statement IV: Freons are quickly decomposed near the earth's surface and rarely reach the stratosphere.

ChemistryHaloalkanes and HaloarenesNamed reactionsHard

Q620Four named reactions start from a halogen compound or a diazonium salt. Match each reagent set in List I with the organic product it gives in List II.

Column I

Column II

P. Bromobenzene + bromomethane + Na in dry ether

1. Chlorobenzene

Q. Bromobenzene + Na in dry ether

2. Toluene

R. Benzenediazonium chloride + Cu₂Cl₂/HCl

3. Iodoethane

S. Bromoethane + NaI in dry acetone

4. Biphenyl

ChemistryHaloalkanes and HaloarenesReactions of haloarenesHard

Q621Which compound undergoes substitution of chlorine by OH⁻ most easily?

BiologyHuman Health and DiseaseCommon diseases in humansEasy

Q622A patient has sustained high fever (39° to 40°C), weakness and stomach pain, and the disease is confirmed by the Widal test. Which pathogen is responsible?

BiologyHuman Health and DiseaseCommon diseases in humansEasy

Q623Which stage of the malarial parasite enters the human body through the bite of an infected female Anopheles mosquito?

BiologyHuman Health and DiseaseAcquired immunityEasy

Q624The yellowish fluid called colostrum, secreted by the mother during the initial days of lactation, is rich in which antibody class?

BiologyHuman Health and DiseaseActive and passive immunityMedium

Q625Statements I and II below compare ways of acquiring immunity. Which of the options is correct?

Statement I: The antibodies a newborn receives through colostrum provide passive immunity.
Statement II: Immunity produced by vaccination with weakened pathogens is passive immunity.

BiologyHuman Health and DiseaseAIDSMedium

Q626Read the Assertion and the Reason about the course of HIV infection and choose the correct option.

Assertion (A): In an HIV-infected person, the number of helper T lymphocytes progressively decreases.
Reason (R): The virus enters helper T lymphocytes, replicates in them and produces progeny viruses that attack more cells.

BiologyHuman Health and DiseaseCommon diseases in humansMedium

Q627Match the pathogen in Column I with the feature in Column II.

Column I

Column II

P. Wuchereria bancrofti

1. Dry, scaly lesions on skin, nails and scalp

Q. Entamoeba histolytica

2. Chronic inflammation of lymphatic vessels of the lower limbs

R. Trichophyton

3. Infection of the large intestine with mucus and blood in stools

S. Plasmodium falciparum

4. Most serious, malignant form of malaria

BiologyHuman Health and DiseaseLymphoid organsMedium

Q628Which pair of organs consists only of primary lymphoid organs?

BiologyHuman Health and DiseaseCancerMedium

Q629Normal cells show contact inhibition. What is the effect of its loss in cancer cells?

BiologyHuman Health and DiseaseDrugs, alcohol and addictionHard

Q630Which pairing of a drug with its source and action is correct?

BiologyHuman Health and DiseaseAIDSHard

Q631Which statement about HIV and its replication is correct?

BiologyHuman ReproductionThe Male Reproductive SystemEasy

Q632Within the seminiferous tubules of the human testis, which cells provide nutrition to the developing germ cells and are regulated by the pituitary hormone FSH?

BiologyHuman ReproductionThe Female Reproductive SystemEasy

Q633In humans, fertilisation of the ovum by a sperm normally occurs in which part of the female reproductive tract?

BiologyHuman ReproductionGametogenesis — SpermatogenesisEasy

Q634One primary spermatocyte undergoes meiosis I followed by meiosis II. How many functional, haploid spermatids does a single primary spermatocyte ultimately give rise to?

BiologyHuman ReproductionGametogenesis — OogenesisMedium

Q635During oogenesis, the primary oocyte completes meiosis I just before ovulation. This first meiotic division is markedly unequal in terms of cytoplasm distribution. What are the two products of this division?

BiologyHuman ReproductionMenstrual CycleMedium

Q636Around the 14th day of a typical 28-day menstrual cycle, a sharp mid-cycle surge of a pituitary hormone triggers rupture of the Graafian follicle and release of the secondary oocyte. Which hormone surge is directly responsible for triggering ovulation?

BiologyHuman ReproductionMenstrual CycleMedium

Q637Consider the following statements about the phases of the human menstrual cycle. Which one/ones is/are correct?

Statement I: During the follicular (proliferative) phase, the growing Graafian follicle secretes estrogen, which causes the uterine endometrium to regenerate and thicken.
Statement II: During the luteal (secretory) phase, the corpus luteum secretes progesterone, which further prepares the endometrium to receive and support a possible embryo.

BiologyHuman ReproductionFertilisation and ImplantationMedium

Q638During fertilisation in humans, a sperm reaches the ovum in the ampullary region of the fallopian tube. Regarding the events that follow, which statement(s) is/are correct?

Statement I: Entry of the sperm into the secondary oocyte induces it to complete its second meiotic division, which is unequal and forms a second polar body and a haploid ovum (ootid).
Statement II: A sperm coming in contact with the zona pellucida layer of the ovum induces changes in the membrane that block the entry of additional sperms, ensuring that only one sperm fertilises an ovum.

BiologyHuman ReproductionPregnancy and Embryonic DevelopmentHard

Q639The placenta acts as an endocrine tissue during pregnancy. Read the Assertion and Reason below about human chorionic gonadotropin (hCG), judge whether each is true, and select the option that correctly relates them.

Assertion (A): The presence of human chorionic gonadotropin (hCG) in a woman's body can be used as an indicator of pregnancy.
Reason (R): hCG is secreted by the placenta and, like hPL and relaxin, is produced in women only during pregnancy.

BiologyHuman ReproductionParturition and LactationMedium

Q640Parturition (childbirth) is initiated by signals that originate mainly from the fully developed foetus and the placenta, producing mild uterine contractions known as the 'foetal ejection reflex.' Which hormone's release is progressively amplified during labour through a positive feedback loop with these uterine contractions?

BiologyHuman ReproductionHormones of the Reproductive SystemHard

Q641Match the hormone in Column I with its correct source and a key role or feature in Column II, then choose the option in which all four matches are correct.

Column I

Column II

P. Follicle-stimulating hormone (FSH)

1. Secreted by the placenta; produced in women only during pregnancy

Q. Luteinising hormone (LH)

2. Secreted by the anterior pituitary; acts on Leydig cells to stimulate androgen secretion and, at its mid-cycle surge, induces ovulation

R. Human chorionic gonadotropin (hCG)

3. Secreted by the anterior pituitary; acts on Sertoli cells and stimulates growth of ovarian follicles

S. Prolactin

4. Secreted by the anterior pituitary; regulates growth of the mammary glands and formation of milk in them

PhysicsMagnetism and MatterDipole in a uniform fieldEasy

Q642A bar magnet of magnetic moment 2.5 A m² is held with its axis at 30° to a uniform magnetic field of 0.040 T. What is the torque on it?

PhysicsMagnetism and MatterThe electrostatic analogMedium

Q643A short bar magnet has magnetic moment 0.50 A m². What is the magnetic field due to it at a point on its equatorial line 10 cm from its centre? (μ₀/4π = 10⁻⁷ T m A⁻¹)

PhysicsMagnetism and MatterDiamagnetismEasy

Q644Which one of the following substances is diamagnetic?

PhysicsMagnetism and MatterMagnetisation and magnetic intensityMedium

Q645A long solenoid with 500 turns per metre carries a current of 1.5 A. Its core is filled with a ferromagnetic material of relative permeability 800. What are the magnetic intensity H and the magnetic field B inside the core? (μ₀ = 4π × 10⁻⁷ T m A⁻¹)

PhysicsMagnetism and MatterParamagnetismMedium

Q646Samples of a paramagnet, a diamagnet, a superconductor and a ferromagnet are studied in a lab. Which of the following observations about such materials are correct?

I. The susceptibility of a paramagnetic material depends on its temperature.
II. Diamagnetic materials have a small negative susceptibility.
III. A superconductor expels a magnetic field completely and behaves as a perfect diamagnet, with μᵣ = 0.
IV. A ferromagnetic material remains ferromagnetic however much it is heated.

PhysicsMagnetism and MatterGauss's law for magnetismMedium

Q647Read the Assertion (A) and Reason (R) about the magnetic field lines of a bar magnet and choose the correct option.

Assertion (A): Unlike electric field lines, the magnetic field lines of a bar magnet have no starting point or end point; they do not stop at the poles but continue through the magnet from S to N.
Reason (R): Isolated magnetic poles (monopoles) are not known to exist, so a magnetic field has no sources or sinks on which its lines could begin or end.

PhysicsMagnetism and MatterMagnetisation and magnetic intensityHard

Q648A uniformly magnetised bar magnet has magnetic moment m. It is cut into four identical pieces by one cut along its length (along the axis) and one cut across it (perpendicular to the axis). Assume the cutting does not change the magnetisation (magnetic moment per unit volume) of the material. What is the magnetic moment of each piece?

PhysicsMagnetism and MatterThe electrostatic analogHard

Q649The magnetic field of a short bar magnet at a point on its axis, at distance r from its centre, has the same magnitude as its field at a point on the equatorial line at distance x from the centre. What is x?

PhysicsMagnetism and MatterGauss's law for magnetismMedium

Q650A closed spherical surface is drawn so that it encloses only the N-pole end of a long bar magnet; the rest of the magnet passes out through the surface. What is the net magnetic flux out of this closed surface?

PhysicsMagnetism and MatterFerromagnetismEasy

Q651Match each material in List I with the description of its magnetic susceptibility χ in List II.

Column I

Column II

P. Bismuth

1. χ = −1

Q. Gadolinium

2. Small and negative

R. Aluminium

3. Small and positive

S. A superconductor (below its critical temperature)

4. Very large and positive (χ ≫ 1)

BiologyMicrobes in Human WelfareMicrobes in household productsEasy

Q652The large holes in Swiss cheese are produced by the release of carbon dioxide from which microbe?

BiologyMicrobes in Human WelfareMicrobes in industrial productsEasy

Q653The first antibiotic to be discovered, penicillin, is obtained from which organism?

BiologyMicrobes in Human WelfareBiogasEasy

Q654Which group of microbes is mainly responsible for generating methane in a biogas plant and also lives in the rumen of cattle?

BiologyMicrobes in Human WelfareFermented beveragesMedium

Q655Statements I and II below concern the production of alcoholic drinks by yeast. Which of the options is correct?

Statement I: Wine and beer are produced without distillation of the fermented broth.
Statement II: Whisky, brandy and rum are produced without distillation.

BiologyMicrobes in Human WelfareSewage treatmentMedium

Q656Read the Assertion and the Reason about the secondary stage of sewage treatment, and choose the correct option.

Assertion (A): The biological treatment of effluent in aeration tanks greatly reduces its BOD.
Reason (R): Vigorous aeration lets aerobic microbes grow as flocs that consume much of the organic matter.

BiologyMicrobes in Human WelfareMicrobes in industrial productsMedium

Q657Match the organic acid in Column I with the microbe that produces it in Column II.

Column I

Column II

P. Citric acid

1. Aspergillus niger

Q. Acetic acid

2. Acetobacter aceti

R. Butyric acid

3. Clostridium butylicum

S. Lactic acid

4. Lactobacillus

BiologyMicrobes in Human WelfareBioactive moleculesMedium

Q658Statins, used to lower blood cholesterol, are obtained from which microbe, and how do they act?

BiologyMicrobes in Human WelfareSewage treatmentMedium

Q659A water sample from a river is found to have a very high biochemical oxygen demand. What does this indicate?

BiologyMicrobes in Human WelfareBiofertilisersHard

Q660Which of the following pairings of a microbe and its role is INCORRECT?

BiologyMicrobes in Human WelfareBiocontrol agentsHard

Q661Which description of the baculoviruses used in integrated pest management is correct?

BiologyMolecular Basis of InheritanceStructure of DNAEasy

Q662The two strands of a DNA double helix are held together by hydrogen bonds between complementary nitrogenous bases. A cytosine on one strand always pairs with which base on the complementary strand, and through how many hydrogen bonds?

BiologyMolecular Basis of InheritanceStructure of DNAEasy

Q663The two polynucleotide strands of a DNA double helix run in opposite directions, one 5'→3' and the other 3'→5'. This arrangement of the two strands is described as:

BiologyMolecular Basis of InheritanceThe Search for Genetic MaterialMedium

Q664In Frederick Griffith's experiment, mice injected with a mixture of heat-killed S-strain (smooth, virulent) Streptococcus pneumoniae and live R-strain (rough, non-virulent) bacteria died, and living S-strain bacteria were recovered from the dead mice. What did Griffith conclude from this result?

BiologyMolecular Basis of InheritanceThe Genetic Material is DNA — Hershey-Chase experimentMedium

Q665Hershey and Chase used bacteriophages labelled separately with radioactive sulphur (³⁵S) and radioactive phosphorus (³²P) to infect E. coli, then agitated the mixture in a blender before centrifuging. Which observation confirmed that DNA, and not protein, is the genetic material?

BiologyMolecular Basis of InheritanceReplication — Meselson-Stahl experimentHard

Q666E. coli cells were grown for many generations in a medium containing only the heavy nitrogen isotope ¹⁵N, so that all their DNA became fully heavy (¹⁵N/¹⁵N). The cells were then shifted to a medium containing only the light isotope ¹⁴N and allowed to divide exactly three times. Assuming semiconservative replication, what fraction of the DNA molecules present after the third division is completely light (¹⁴N/¹⁴N)?

BiologyMolecular Basis of InheritanceReplication — enzymes and Okazaki fragmentsMedium

Q667DNA polymerase can add nucleotides only in the 5'→3' direction. Because the two template strands at a replication fork are antiparallel, one new strand (the lagging strand) cannot be synthesised continuously. How is the lagging strand actually made?

BiologyMolecular Basis of InheritanceTranscription UnitHard

Q668RNA polymerase transcribes only one strand of a DNA segment, even though the DNA is double-stranded. Read the Assertion and Reason below on why transcription is restricted to a single strand, and choose the correct option.

Assertion (A): Within a transcription unit, only one of the two DNA strands (the template strand) is transcribed into RNA.
Reason (R): If both strands were transcribed at the same time, the two RNA molecules formed would be complementary to each other and would pair into a double-stranded RNA that could not be translated into protein.

BiologyMolecular Basis of InheritanceGenetic CodeMedium

Q669Two statements about the genetic code are given below. Which one/ones is/are correct?

Statement I: The genetic code is degenerate, meaning a single amino acid can be specified by more than one codon.
Statement II: The genetic code is ambiguous, meaning a single codon can specify more than one amino acid.

BiologyMolecular Basis of InheritanceRegulation of Gene Expression — the lac operonMedium

Q670Consider the following statements about regulation of the lac operon in E. coli. Which one/ones is/are correct?

Statement I: In the absence of an inducer such as lactose, the repressor protein made by the i gene binds to the operator region and prevents RNA polymerase from transcribing the structural genes.
Statement II: The inducer (lactose or allolactose) switches the operon on by binding directly to the operator DNA and physically pushing the repressor off it.

BiologyMolecular Basis of InheritanceDNA FingerprintingEasy

Q671DNA fingerprinting relies on comparing regions of the genome that show a high degree of polymorphism (variation) between individuals. Which class of DNA sequence is exploited for this purpose?

PhysicsMoving Charges and MagnetismMotion in a magnetic fieldEasy

Q672A proton and an alpha-particle enter the same uniform magnetic field with equal speeds, moving at right angles to the field. Taking the alpha-particle's mass as 4 times and its charge as 2 times that of the proton, what is the ratio r_α/r_p of the radii of their circular paths?

PhysicsMoving Charges and MagnetismMagnetic field and the Lorentz forceEasy

Q673A charged particle moves in a uniform magnetic field with its velocity perpendicular to the field, and no other force acts on it. Which quantity stays constant during the motion?

PhysicsMoving Charges and MagnetismMotion in a magnetic fieldMedium

Q674A proton (m = 1.67 × 10⁻²⁷ kg, q = 1.6 × 10⁻¹⁹ C) enters a uniform magnetic field of 0.10 T with a speed of 4.0 × 10⁵ m s⁻¹, its velocity making 60° with the field. What is the pitch of its helical path?

PhysicsMoving Charges and MagnetismBiot–Savart lawMedium

Q675A wire carrying 4.0 A is bent into a quarter-circle arc of radius 10 cm, with straight leads running radially in and out of the arc's centre. What is the magnetic field at the centre of the arc? (μ₀ = 4π × 10⁻⁷ T m A⁻¹)

PhysicsMoving Charges and MagnetismForce between parallel currentsMedium

Q676Two long straight parallel wires 5.0 cm apart in air carry currents of 10 A and 15 A in opposite directions. What is the force per metre length between them? (μ₀ = 4π × 10⁻⁷ T m A⁻¹)

PhysicsMoving Charges and MagnetismThe moving coil galvanometerMedium

Q677A galvanometer of coil resistance 20 Ω gives full-scale deflection for a current of 5.0 mA. How should it be converted into a voltmeter of range 0–10 V?

PhysicsMoving Charges and MagnetismTorque on a current loopHard

Q678A rectangular coil of 50 turns, 4.0 cm × 5.0 cm, carries a current of 2.0 A in a uniform magnetic field of 0.20 T. The plane of the coil makes an angle of 30° with the field. What is the torque on the coil?

PhysicsMoving Charges and MagnetismMotion in a magnetic fieldMedium

Q679Electrons of different speeds are injected perpendicular to the same uniform magnetic field. Read the Assertion (A) and Reason (R) about their motion and choose the correct option.

Assertion (A): All the electrons take the same time to complete one revolution.
Reason (R): The radius of the circle is proportional to the speed, so the circumference and the speed increase in the same proportion.

PhysicsMoving Charges and MagnetismAmpere's circuital lawEasy

Q680Match each current arrangement in List I with the magnitude of the magnetic field it produces (List II).

Column I

Column II

P. Long straight wire, at distance r

1. μ₀nI

Q. Centre of a circular coil of N turns and radius R

2. μ₀IR²/2x³

R. Inside a long solenoid with n turns per unit length

3. μ₀I/2πr

S. On the axis of a single loop of radius R, at distance x ≫ R

4. μ₀NI/2R

PhysicsMoving Charges and MagnetismAmpere's circuital lawHard

Q681A long straight solid wire of radius a carries a steady current distributed uniformly over its cross-section. What is the ratio of the magnetic field at a distance a/2 from the axis to the field at a distance 2a from the axis?

PhysicsNucleiSize of the nucleusEasy

Q682Two nuclei have mass numbers 216 and 27. What is the ratio of the radius of the heavier nucleus to that of the lighter one?

PhysicsNucleiAtomic masses and composition of nucleusEasy

Q683Isotones are nuclides with the same number of neutrons but different numbers of protons. Which pair below are isotones?

PhysicsNucleiMass–energy and nuclear binding energyMedium

Q684The atomic mass of ⁷₃Li is 7.016003 u. Using m(¹H) = 1.007825 u, mₙ = 1.008665 u and 1 u = 931.5 MeV/c², find the binding energy per nucleon of lithium-7.

PhysicsNucleiNuclear energy: fission and fusionMedium

Q685In one fusion branch, two deuterons combine as ²H + ²H → ³He + n. Using m(²H) = 2.014102 u, m(³He) = 3.016029 u, mₙ = 1.008665 u and 1 u = 931.5 MeV/c², what is the Q-value?

PhysicsNucleiNuclear forceMedium

Q686A nucleus holds many protons together despite their mutual repulsion. Which of these statements about the force responsible are correct?

I. It is much stronger than the Coulomb force at distances of a few femtometres.
II. It acts almost equally between proton–proton, neutron–neutron and proton–neutron pairs.
III. It falls off as the inverse square of distance, like gravity.
IV. It becomes strongly repulsive when nucleons come closer than about 0.8 fm.

PhysicsNucleiMass–energy and nuclear binding energyMedium

Q687A uranium-235 nucleus captures a slow neutron and splits into two medium-mass fragments with a large release of energy. Read the Assertion (A) and Reason (R) and choose the correct option.

Assertion (A): Splitting a nucleus of mass number about 240 into two nuclei of mass number about 120 releases energy.
Reason (R): The binding energy per nucleon is higher for nuclei near A ≈ 120 than for nuclei near A ≈ 240.

PhysicsNucleiNuclear energy: fission and fusionHard

Q688Each fission of a ²³⁵U nucleus releases about 200 MeV. If every nucleus in 1.0 g of pure ²³⁵U undergoes fission, about how much energy is released? (Nₐ = 6.02 × 10²³ mol⁻¹, 1 MeV = 1.6 × 10⁻¹³ J.)

PhysicsNucleiNuclear energy: fission and fusionHard

Q689Two deuterons (²₁H) fuse to form a helium nucleus (⁴₂He). Take the binding energy per nucleon as 1.1 MeV for the deuteron and 7.0 MeV for the helium nucleus (approximate values, given). About how much energy is released in this fusion?

PhysicsNucleiMass–energy and nuclear binding energyEasy

Q690Match each nuclear quantity in List I with its approximate value in List II.

Column I

Column II

P. Energy equivalent of 1 atomic mass unit

1. About 8.75 MeV

Q. Constant R₀ in R = R₀A^(1/3)

2. About 200 MeV

R. Maximum binding energy per nucleon (near A ≈ 56)

3. 931.5 MeV

S. Energy released in one fission of ²³⁵U

4. About 1.2 fm

PhysicsNucleiSize of the nucleusMedium

Q691Taking the mass of a nucleon as 1.66 × 10⁻²⁷ kg and R = R₀A^(1/3) with R₀ = 1.2 fm, what is the approximate density of nuclear matter?

BiologyOrganisms and PopulationsPopulation growthEasy

Q692A population with unlimited food and space increases along a J-shaped curve. This growth is described by dN/dt = rN and is called:

BiologyOrganisms and PopulationsPopulation interactionsEasy

Q693An orchid grows on the branch of a mango tree, using it only for support and not harming it. This interaction is:

BiologyOrganisms and PopulationsPopulation attributesEasy

Q694A population of 50 snails in a pond produces 10 young ones in a year. What is the birth rate?

BiologyOrganisms and PopulationsPopulation growthMedium

Q695Statements I and II below compare logistic and exponential models of population growth. Which of the options is correct?

Statement I: In logistic growth, the growth rate declines as the population size approaches the carrying capacity.
Statement II: In exponential growth, the growth rate declines as the population size increases.

BiologyOrganisms and PopulationsCompetitionMedium

Q696Read the Assertion and the Reason about several closely related warbler species foraging on the same tree, and choose the correct option.

Assertion (A): Several closely related warbler species can live together on the same tree.
Reason (R): Each species forages in a different part of the tree, so they partition the resources.

BiologyOrganisms and PopulationsPopulation interactionsMedium

Q697Match the interaction in Column I with the example in Column II.

Column I

Column II

P. Mutualism

1. A fungus and an alga living together as a lichen

Q. Commensalism

2. Barnacles growing on the back of a whale

R. Parasitism

3. A liver fluke needing a snail and a fish as intermediate hosts

S. Competition

4. One barnacle species excluding another from part of a rocky coast

BiologyOrganisms and PopulationsPopulation growthMedium

Q698A population begins with 500 individuals. During a year there are 60 births, 40 deaths, 25 immigrants and 15 emigrants. What is the population size at the end of the year?

BiologyOrganisms and PopulationsPopulation growthMedium

Q699A population grows logistically with r = 0.2 per year and carrying capacity K = 1000. What is dN/dt when N = 250?

BiologyOrganisms and PopulationsPredationHard

Q700When the starfish Pisaster was removed from an enclosed rocky intertidal area, more than ten invertebrate species disappeared. What was the cause?

BiologyOrganisms and PopulationsCompetitionHard

Q701Which statement about competition between species is correct?

BiologyPrinciples of Inheritance and VariationMendel's Laws of InheritanceEasy

Q702Mendel crossed a true-breeding tall pea plant (TT) with a true-breeding dwarf pea plant (tt). All F₁ plants were tall, but when the F₁ plants were self-pollinated, dwarf plants reappeared in F₂, exactly as dwarf as the original dwarf parent, with no blending. Which Mendelian law is based on this recovery of the parental characters unchanged in F₂, and explains it by the separation of the two alleles into different gametes?

BiologyPrinciples of Inheritance and VariationMendel's Laws of InheritanceEasy

Q703A pea plant with the genotype Tt is grown and its outward height (tall) is recorded. With respect to the height gene, this plant is best described as:

BiologyPrinciples of Inheritance and VariationInheritance of Two GenesMedium

Q704In garden pea, round seed shape (R) is dominant over wrinkled (r), and yellow seed colour (Y) is dominant over green (y); the two genes assort independently. A dihybrid F₁ plant of genotype RrYy is self-pollinated to raise 1,600 F₂ seeds. Based on the expected 9:3:3:1 ratio, how many of these F₂ seeds are expected to be wrinkled and yellow?

BiologyPrinciples of Inheritance and VariationDeviations from Mendelism — Incomplete DominanceMedium

Q705In the dog flower (snapdragon, Antirrhinum sp.), flower colour shows incomplete dominance: a true-breeding red-flowered plant (RR) crossed with a true-breeding white-flowered plant (rr) gives pink-flowered F₁ plants (Rr). If these pink F₁ plants are self-pollinated, what phenotypic ratio is expected among the F₂ plants?

BiologyPrinciples of Inheritance and VariationDeviations from Mendelism — Multiple AllelesMedium

Q706The ABO blood group in humans is controlled by multiple alleles IA, IB and i, where IA and IB are co-dominant and both are dominant over i. A man with blood group A (genotype IAi) marries a woman with blood group B (genotype IBi). What proportion of their children is expected to have blood group O?

BiologyPrinciples of Inheritance and VariationChromosomal Theory of Inheritance — Linkage and RecombinationMedium

Q707With respect to linkage and recombination, which statement(s) is/are correct?

Statement I: Genes located far apart on the same chromosome show a higher recombination frequency than genes located close together on that chromosome.
Statement II: Linked genes located on the same chromosome always show 100% recombination in every generation, identical to genes located on different chromosomes.

BiologyPrinciples of Inheritance and VariationSex DeterminationMedium

Q708Regarding sex-determination mechanisms, which statement(s) is/are correct?

Statement I: In humans, sex is determined by whether a sperm carrying an X or a Y chromosome fertilises the egg, making the male the heterogametic sex.
Statement II: In birds, males are heterogametic (ZW) and females are homogametic (ZZ), the mirror image of the human XY system.

BiologyPrinciples of Inheritance and VariationPedigree Analysis and Mendelian DisordersHard

Q709Haemophilia is a sex-linked disorder in which a single protein of the blood-clotting cascade is affected, so even a small cut can bleed without stopping. Evaluate the Assertion about how often the disorder appears in each sex and the Reason offered for it.

Assertion (A): Haemophilia is much more commonly observed in human males than in human females.
Reason (R): Haemophilia is caused by a recessive allele located on the X chromosome, so a male needs only one copy of the allele to be affected, whereas a female needs two copies.

BiologyPrinciples of Inheritance and VariationMendelian Disorders — Sickle-cell AnaemiaEasy

Q710Sickle-cell anaemia is caused by the substitution of a single amino acid in the beta-globin chain of haemoglobin, which makes red blood cells become rigid and sickle-shaped under low-oxygen conditions. What inheritance pattern does this disorder show?

BiologyPrinciples of Inheritance and VariationChromosomal DisordersHard

Q711Match the condition in Column I with its correct karyotype/chromosomal basis in Column II, then choose the option in which all four matches are correct.

Column I

Column II

P. Down syndrome

1. 47, XXY (an extra X chromosome in a male)

Q. Klinefelter syndrome

2. 45, X0 (a single X chromosome, no second sex chromosome)

R. Turner syndrome

3. Trisomy 21 — 47 chromosomes, an extra copy of chromosome 21

S. Normal human female karyotype

4. 46, XX

PhysicsRay Optics and Optical InstrumentsReflection of light by spherical mirrorsEasy

Q712An object is placed on the principal axis 30 cm in front of a concave mirror of focal length 20 cm. Using the Cartesian sign convention, where and what kind of image is formed?

PhysicsRay Optics and Optical InstrumentsTotal internal reflectionEasy

Q713Light travels at 2.0 × 10⁸ m s⁻¹ in a certain transparent solid and at 3.0 × 10⁸ m s⁻¹ in air. What is the critical angle for light going from the solid towards its boundary with air?

PhysicsRay Optics and Optical InstrumentsPower of a lens and combination of thin lenses in contactEasy

Q714A thin converging lens of focal length 25 cm is placed in contact with a thin diverging lens of focal length 40 cm (both focal lengths given as magnitudes). What is the power of the combination?

PhysicsRay Optics and Optical InstrumentsRefraction: apparent depthMedium

Q715A coin lies at the bottom of a tank. The tank holds a 24 cm deep layer of water (refractive index 4/3), and on top of the water floats a 15 cm thick layer of a transparent oil (refractive index 1.50). Viewed from air almost vertically above (near-normal incidence), how far below the top surface of the oil does the coin appear to be?

PhysicsRay Optics and Optical InstrumentsRefraction by a lens: lensmaker's formulaMedium

Q716A thin biconvex lens of glass (refractive index 1.50) has radii of curvature 20 cm and 30 cm for its two faces. Its focal length in air is 24 cm. The lens is completely immersed in a transparent liquid of refractive index 1.25. What is its focal length in the liquid?

PhysicsRay Optics and Optical InstrumentsRefraction through a prismMedium

Q717A glass prism has a refracting angle of 60°. For monochromatic light, the angle of minimum deviation is measured to be 38°. What is the refractive index of the glass?

PhysicsRay Optics and Optical InstrumentsOptical instruments: telescopeMedium

Q718Consider the following statements about a refracting astronomical telescope used in normal adjustment (final image at infinity). Which of the statements are correct?

I. The distance between the objective and the eyepiece equals f_o + f_e.
II. Its magnifying power is f_o/f_e, so the objective should have a much larger focal length than the eyepiece.
III. Increasing the diameter of the objective (keeping its focal length unchanged) increases the magnifying power.
IV. The final image seen through the telescope is erect.

PhysicsRay Optics and Optical InstrumentsOptical instruments: compound microscopeHard

Q719A compound microscope has an objective of focal length 1.0 cm and an eyepiece of focal length 4.0 cm. An object is placed 1.2 cm in front of the objective, and the eyepiece is adjusted so that the final image forms at the least distance of distinct vision, 25 cm from the eyepiece (the eye is held close to the eyepiece). What is the magnitude of the magnifying power?

PhysicsRay Optics and Optical InstrumentsRefraction by lenses: image by successive lensesHard

Q720A thin converging lens L₁ of focal length 20 cm and a thin diverging lens L₂ of focal length 30 cm (magnitude) are placed coaxially 40 cm apart, with L₂ to the right of L₁. An object is placed on the axis 30 cm to the left of L₁, and light travels from left to right. Using the Cartesian sign convention, where is the final image formed?

BiologyReproductive HealthBirth control: oral pillsEasy

Q721Saheli, an oral contraceptive developed in India, differs from conventional pills in being:

BiologyReproductive HealthBirth control: IUDsEasy

Q722How do copper-releasing intra-uterine devices such as CuT mainly prevent pregnancy?

BiologyReproductive HealthMedical termination of pregnancyEasy

Q723In which year did the Government of India legalise medical termination of pregnancy (MTP) with certain conditions?

BiologyReproductive HealthBirth control: sterilisationMedium

Q724Statements I and II below describe surgical sterilisation. Which of the options is correct?

Statement I: Vasectomy prevents pregnancy by cutting or tying the vas deferens, blocking the transport of sperms.
Statement II: Tubectomy prevents pregnancy by stopping the formation of ova in the ovary.

BiologyReproductive HealthBirth control: natural methodsMedium

Q725Read the Assertion and the Reason about lactational amenorrhea as a contraceptive, and choose the correct option.

Assertion (A): Lactational amenorrhea is an effective contraceptive method only for a limited period after parturition, up to about six months.
Reason (R): During intense lactation, ovulation and the menstrual cycle do not occur.

BiologyReproductive HealthAssisted reproductive technologiesMedium

Q726Match each assisted reproductive technique in Column I with the way it is carried out in Column II.

Column I

Column II

P. ZIFT

1. Zygote or early embryo with up to 8 blastomeres transferred into the fallopian tube

Q. IUT

2. Embryo with more than 8 blastomeres transferred into the uterus

R. GIFT

3. Ovum from a donor transferred into the fallopian tube of a female who cannot produce ova

S. ICSI

4. A sperm injected directly into an ovum in the laboratory

BiologyReproductive HealthBirth control: natural methodsMedium

Q727In the periodic abstinence method, couples avoid coitus during which days of a menstrual cycle?

BiologyReproductive HealthSexually transmitted infectionsMedium

Q728Which set contains only STIs that are not completely curable even when detected early?

BiologyReproductive HealthBirth control: pillsHard

Q729Which description of the oral contraceptive pills containing progestogen or progestogen-estrogen is correct?

BiologyReproductive HealthBirth control: IUDsHard

Q730Which of the following is a hormone-releasing intra-uterine device?

PhysicsSemiconductor Electronics: Materials, Devices and Simple CircuitsExtrinsic semiconductorEasy

Q731A pure silicon crystal is doped with a small amount of arsenic, a group-15 element. What kind of semiconductor results, and what are its majority carriers?

PhysicsSemiconductor Electronics: Materials, Devices and Simple CircuitsClassification of metals, conductors and semiconductorsEasy

Q732Diamond (carbon), silicon and germanium all have the same crystal structure with four valence electrons per atom. Which ordering of their energy band gaps is correct?

PhysicsSemiconductor Electronics: Materials, Devices and Simple CircuitsExtrinsic semiconductorMedium

Q733A silicon sample at a temperature where nᵢ = 2.4 × 10¹⁹ m⁻³ is doped with donors at a concentration of 4.0 × 10²² m⁻³. Taking every donor as ionised, what is the hole concentration?

PhysicsSemiconductor Electronics: Materials, Devices and Simple CircuitsApplication of junction diode as a rectifierEasy

Q734A full-wave rectifier built from two diodes and a centre-tapped transformer is fed from a 60 Hz AC supply. What is the fundamental frequency of the pulsating DC output?

PhysicsSemiconductor Electronics: Materials, Devices and Simple CircuitsSemiconductor diodeMedium

Q735A silicon p-n junction with built-in barrier V₀ is studied first unbiased, then with an external voltage V in forward bias and in reverse bias. Which of these statements are correct?

I. Under forward bias the effective barrier height falls to V₀ − V.
II. Under reverse bias the depletion region becomes wider.
III. The small reverse current is due to majority carriers diffusing across the junction.
IV. With no bias, the diffusion current and drift current across the junction are equal and opposite.

PhysicsSemiconductor Electronics: Materials, Devices and Simple CircuitsSemiconductor diodeMedium

Q736In a forward-biased silicon diode, the current rises from 10 mA to 20 mA when the voltage across it is increased from 0.70 V to 0.75 V. What is the diode's dynamic resistance in this range?

PhysicsSemiconductor Electronics: Materials, Devices and Simple CircuitsSemiconductor diodeHard

Q737A 5.0 V battery feeds two parallel branches. Each branch is a 1.0 kΩ resistor in series with an identical silicon diode (forward drop 0.7 V); in one branch the diode points along the current direction and in the other it is reversed. What current does the battery supply? (Treat the reversed diode as an open switch.)

PhysicsSemiconductor Electronics: Materials, Devices and Simple CircuitsExtrinsic semiconductorHard

Q738A silicon wafer (nᵢ = 1.5 × 10¹⁶ m⁻³) is doped with indium, a group-13 element, at a concentration of 2.5 × 10²² m⁻³. Taking every dopant atom as ionised, what type of semiconductor is the wafer, and what is the ratio of its majority-carrier concentration to its minority-carrier concentration?

PhysicsSemiconductor Electronics: Materials, Devices and Simple CircuitsIntrinsic semiconductorMedium

Q739Match each element in List I with its role or property in List II.

Column I

Column II

P. Phosphorus added to silicon

1. Acceptor impurity

Q. Boron added to silicon

2. Band gap about 0 eV, behaves as a metal

R. Pure germanium

3. Donor impurity

S. Tin (group 14, like silicon)

4. Intrinsic semiconductor, band gap about 0.7 eV

PhysicsSemiconductor Electronics: Materials, Devices and Simple CircuitsIntrinsic semiconductorMedium

Q740A strip of pure silicon is warmed from room temperature to 100 °C while its resistance is monitored, and the resistance drops. Read the Assertion (A) and Reason (R) and choose the correct option.

Assertion (A): The electrical conductivity of an intrinsic semiconductor increases as its temperature rises.
Reason (R): Thermal energy breaks more covalent bonds, lifting electrons into the conduction band and creating an equal number of holes.

BiologySexual Reproduction in Flowering PlantsThe embryo sacEasy

Q741A typical angiosperm embryo sac at maturity is described as:

BiologySexual Reproduction in Flowering PlantsMicrosporangiumEasy

Q742Which layer of the microsporangium wall nourishes the developing pollen grains?

BiologySexual Reproduction in Flowering PlantsDouble fertilisationEasy

Q743What is the ploidy of the primary endosperm nucleus formed in double fertilisation?

BiologySexual Reproduction in Flowering PlantsPollinationMedium

Q744Statements I and II below concern pollination types and flower sexuality. Which of the options is correct?

Statement I: Geitonogamy is functionally cross-pollination but genetically similar to autogamy.
Statement II: In monoecious plants such as maize, geitonogamy is prevented.

BiologySexual Reproduction in Flowering PlantsPollinationMedium

Q745Read the Assertion and the Reason about cleistogamous flowers, and choose the correct option.

Assertion (A): Cleistogamous flowers produce assured seed-set even in the absence of pollinators.
Reason (R): These flowers never open, and pollen from the anthers pollinates the stigma within the closed flower.

BiologySexual Reproduction in Flowering PlantsSeed and fruitMedium

Q746Match each seed or fruit term in Column I with the correct description in Column II, then choose the right combination.

Column I

Column II

P. Perisperm

1. Persistent remnant of the nucellus in the seed

Q. Coconut water

2. Free-nuclear endosperm

R. Apple

3. False fruit in which thalamus contributes

S. Banana

4. Fruit that develops without fertilisation

BiologySexual Reproduction in Flowering PlantsPollinationMedium

Q747Which of the following is pollinated by water?

BiologySexual Reproduction in Flowering PlantsThe pollen grainMedium

Q748At what temperature can pollen grains be stored for years in pollen banks?

BiologySexual Reproduction in Flowering PlantsDouble fertilisationHard

Q749The cells of the nucellus of a plant have 16 chromosomes. How many chromosomes are present in the primary endosperm nucleus of that plant?

BiologySexual Reproduction in Flowering PlantsThe pollen grainHard

Q750Which statement about the pollen grain wall is correct?

ChemistrySolutionsHenry's lawEasy

Q751Near room temperature, the Henry's law constant K_H of CO₂ in water is much smaller than that of N₂. What does this tell you, with p = K_H·x?

ChemistrySolutionsAbnormal molar masses and van't Hoff factorEasy

Q752Equal-molality (0.05 m) aqueous solutions of four solutes are cooled. Assuming complete dissociation of electrolytes, which solution freezes at the lowest temperature?

ChemistrySolutionsIdeal and non-ideal solutionsEasy

Q753Which pair of liquids, on mixing, gives a solution showing negative deviation from Raoult's law?

ChemistrySolutionsVapour pressure of liquid–liquid solutionsMedium

Q754Liquids A and B form an ideal solution. At 300 K, p°A = 450 mm Hg and p°B = 150 mm Hg. What is the total vapour pressure of a solution in which the mole fraction of A is 0.40?

ChemistrySolutionsElevation of boiling pointMedium

Q755Dissolving 1.20 g of a non-volatile, non-electrolyte solid in 50.0 g of benzene raises the boiling point by 0.30 K. K_b for benzene is 2.53 K kg mol⁻¹. What is the molar mass of the solid?

ChemistrySolutionsOsmotic pressureMedium

Q756A solution of 2.0 g of a synthetic polymer in enough water to make 250 mL shows an osmotic pressure of 4.0 × 10⁻³ bar at 300 K. Using R = 0.083 L bar mol⁻¹ K⁻¹, what is the molar mass of the polymer?

ChemistrySolutionsAbnormal molar masses and van't Hoff factorMedium

Q757Two aqueous solutions, 0.1 M NaCl and 0.1 M glucose, are compared at the same temperature. Judge the Assertion (A) and the Reason (R) below.

Assertion (A): The NaCl solution has a higher osmotic pressure than the glucose solution.
Reason (R): Each formula unit of NaCl dissociates into two ions, so the NaCl solution holds nearly twice as many solute particles.

ChemistrySolutionsIdeal and non-ideal solutionsMedium

Q758Binary liquid mixtures can behave ideally or deviate from Raoult's law. Which of the statements below are correct?

Statement I: A solution showing positive deviation from Raoult's law absorbs heat on mixing (ΔmixH > 0).
Statement II: A large positive deviation leads to a minimum boiling azeotrope.
Statement III: A solution showing negative deviation expands on mixing (ΔmixV > 0).
Statement IV: An ideal solution obeys Raoult's law over the entire range of composition.

ChemistrySolutionsAbnormal molar masses and van't Hoff factorHard

Q7592.0 g of ethanoic acid (M = 60 g mol⁻¹) dissolved in 100 g of benzene lowers its freezing point by 0.94 K. K_f for benzene is 5.12 K kg mol⁻¹. What percentage of the acid molecules have associated into dimers?

ChemistrySolutionsVapour pressure of liquid–liquid solutionsHard

Q760Liquids X and Y form an ideal solution with p°X = 400 mm Hg and p°Y = 100 mm Hg at a certain temperature. The vapour in equilibrium with a particular solution contains equal moles of X and Y. What is the mole fraction of X in the liquid?

ChemistryThe d- and f-Block ElementsFormation of coloured ionsEasy

Q761Which of these aquated ions is colourless?

ChemistryThe d- and f-Block ElementsElectronic configuration of d-block elementsEasy

Q762Zinc is placed in the d-block, yet it is not regarded as a transition element. Why?

ChemistryThe d- and f-Block ElementsLanthanoid contractionEasy

Q763As a result of the lanthanoid contraction, which pair of elements has almost identical atomic radii?

ChemistryThe d- and f-Block ElementsMagnetic propertiesMedium

Q764Which ion has a spin-only magnetic moment of about 3.87 BM?

ChemistryThe d- and f-Block ElementsTrends in M²⁺/M standard electrode potentialsMedium

Q765Which 3d metal has a positive E°(M²⁺/M) value and therefore does not liberate hydrogen from dilute non-oxidising acids?

ChemistryThe d- and f-Block ElementsPotassium dichromateMedium

Q766When sodium hydroxide solution is added to an orange solution of potassium dichromate, the colour turns yellow. What change has occurred?

ChemistryThe d- and f-Block ElementsTrends in M³⁺/M²⁺ electrode potentialsMedium

Q767Cr²⁺ and Mn³⁺ both have a d⁴ configuration, but they behave in opposite ways. Judge the Assertion (A) and the Reason (R) below.

Assertion (A): Cr²⁺ is a strong reducing agent.
Reason (R): On losing an electron Cr²⁺ becomes Cr³⁺, which has the stable configuration with a half-filled t₂g level (d³).

ChemistryThe d- and f-Block ElementsThe lanthanoidsMedium

Q768Most lanthanoids prefer the +3 state, but a few show +2 or +4. Which of the statements below are correct?

Statement I: The principal oxidation state of the lanthanoids is +3.
Statement II: Ce⁴⁺ in aqueous solution is a strong oxidising agent.
Statement III: The lanthanoid contraction arises because 4f electrons shield one another poorly from the nuclear charge.
Statement IV: Eu²⁺ is a strong oxidising agent.

ChemistryThe d- and f-Block ElementsPotassium permanganate and dichromateHard

Q769The product of an oxidation by permanganate or dichromate depends on the substrate and the medium. Match each reaction in List I with the oxidation product of the substrate in List II.

Column I

Column II

P. Acidified KMnO₄ with oxalate ion

1. Sn⁴⁺

Q. KMnO₄ in neutral or faintly alkaline solution with iodide ion

2. S

R. Acidified K₂Cr₂O₇ with H₂S

3. IO₃⁻

S. Acidified K₂Cr₂O₇ with Sn²⁺

4. CO₂

ChemistryThe d- and f-Block ElementsThe actinoidsHard

Q770Which statement about the actinoids is INCORRECT?

PhysicsWave OpticsYoung's double-slit experimentEasy

Q771In a Young's double-slit set-up, the slits are 0.30 mm apart, the screen is 1.5 m away, and light of wavelength 600 nm is used. What is the fringe width?

PhysicsWave OpticsRefraction of a plane waveEasy

Q772Light of wavelength 600 nm in air enters glass of refractive index 1.5. What happens to its frequency and wavelength in the glass?

PhysicsWave OpticsMalus' law and crossed polaroidsMedium

Q773Unpolarised light of intensity I₀ falls on a polaroid P₁. The light then passes through a second polaroid P₂ whose pass axis is at 60° to that of P₁. What intensity emerges from P₂?

PhysicsWave OpticsCoherent and incoherent additionMedium

Q774Two coherent sources each produce intensity I₀ at a point on a screen. At that point the waves from them have a phase difference of π/3. What is the resultant intensity there?

PhysicsWave OpticsDiffraction at a single slitMedium

Q775Light of wavelength 500 nm falls normally on a single slit of width 0.20 mm. The diffraction pattern is observed on a screen 2.0 m away. What is the linear width of the central bright maximum?

PhysicsWave OpticsYoung's double-slit experimentHard

Q776In a Young's double-slit experiment with light of wavelength 500 nm, the slit separation is 0.60 mm and the screen is 1.2 m away. What is the distance between the third bright fringe on one side of the central bright fringe and the second dark fringe on the other side?

PhysicsWave OpticsCoherent and incoherent additionEasy

Q777Two separate sodium lamps of equal brightness illuminate the same region of a screen. Read the Assertion (A) and Reason (R) and choose the correct option.

Assertion (A): No steady interference fringes are seen on the screen.
Reason (R): The phase of light from each independent source changes randomly in times of about 10⁻¹⁰ s, so there is no constant phase difference between the two.

PhysicsWave OpticsMalus' law and crossed polaroidsHard

Q778Unpolarised light of intensity I₀ passes through two crossed polaroids P₁ and P₃. A third polaroid P₂ is inserted between them with its pass axis at 30° to that of P₁. What intensity now emerges from P₃?

PhysicsWave OpticsWavefronts and Huygens principleMedium

Q779A teacher writes four claims on the board about wavefronts and Huygens' construction. Which of the claims are correct?

I. A point source in a uniform medium produces spherical wavefronts.
II. Rays are perpendicular to the wavefronts, along the direction of energy flow.
III. A thin convex lens turns a plane wavefront into a spherical wavefront converging to its focus.
IV. The energy carried by a light wave depends on its speed, not on its amplitude.

PhysicsWave OpticsInterference, diffraction and seeing themMedium

Q780Match each situation in List I with the condition or result that describes it in List II (n is a whole number, a the slit width, I₀ the intensity from one source).

Column I

Column II

P. Bright fringe in Young's experiment

1. Path difference (n + ½)λ

Q. Dark fringe in Young's experiment

2. Uniform intensity 2I₀, no fringes

R. Minimum in single-slit diffraction

3. a sin θ = nλ, with n ≠ 0

S. Two incoherent sources of equal intensity

4. Path difference nλ