Which sugar reduces Tollens' reagent?
"Which sugar reduces Tollens' reagent?" is a free, interactive Class 12 Chemistry simulation for NEET and JEE, built on the lesson "Disaccharides and the glycosidic link" in Biomolecules. Pick a sugar and a test. Tollens' shows whether a silver mirror forms, hydrolyse splits the sugar into its units, and linkage shows which carbons the glycosidic oxygen joins. A red dot marks a free reducing carbon. Every monosaccharide is reducing. A disaccharide is reducing only if one unit keeps its C1 (or C2 in a ketose) free: maltose and lactose yes, sucrose no. JEE Main asked 50 questions from this chapter across the 42 shifts Lumi has analysed (2017–2026).
From the lesson Disaccharides and the glycosidic link in Biomolecules. Change the values and watch what happens.
In JEE Main
42 shifts analysed
50 questions from Biomolecules across the 42 JEE Main shifts Lumi has analysed (2017–2026).
The idea behind it
NCERT §10.1.3
- Two monosaccharides join by losing a water molecule, leaving an oxide bridge between them. A link between sugar units through oxygen is a glycosidic linkage. Dilute acid or enzymes hydrolyse it back.
- If both reducing groups (the aldehydic or ketonic carbons) are used up in the link, the disaccharide is non-reducing. If one stays free it is reducing.
- Sucrose: C1 of α-D-glucose joined to C2 of β-D-fructose. Both reducing carbons are in the bond, so sucrose is a non-reducing sugar.
- Sucrose is dextrorotatory. Its hydrolysis gives equal moles of D-(+)-glucose (+52.5°) and D-(–)-fructose (–92.4°). Fructose's laevorotation is the larger, so the mixture is laevorotatory.
- The sign of rotation flips from (+) to (–) on hydrolysis; the product is called invert sugar.
- Maltose: two α-D-glucose units, C1 of one joined to C4 of the other. The second unit's C1 can open to a free aldehyde in solution, so maltose is reducing.
- Lactose (milk sugar): β-D-galactose and β-D-glucose linked from C1 of galactose to C4 of glucose. The glucose unit's C1 can give a free aldehyde, so lactose is reducing.
Questions
3 answers
- What does the "Which sugar reduces Tollens' reagent?" simulation show?
- Pick a sugar and a test. Tollens' shows whether a silver mirror forms, hydrolyse splits the sugar into its units, and linkage shows which carbons the glycosidic oxygen joins. A red dot marks a free reducing carbon.
- Does JEE Main ask questions from Biomolecules?
- Yes. JEE Main asked 50 questions from this chapter across the 42 shifts Lumi has analysed (2017–2026).
- Is this simulation free?
- Yes. It is free and runs in the browser on a phone or a laptop. It belongs to the lesson "Disaccharides and the glycosidic link" in Biomolecules (Class 12 Chemistry).
Embed this simulation
Free, with a link back
Teaching this idea? Put the simulation on your own page or LMS with this code.