Question

A non-reducing sugar "A" on hydrolysis gives two reducing monosaccharides. Sugar A is

• A. Glucose
• B. Fructose
• C. Sucrose
• D. Galactose

Answer 1

The correct option is C

Sucrose

Explanation of the correct option:

(C) On hydrolysis of sucrose, we get D-glucose and D-fructose.

${\mathrm{C}}_{12}{\mathrm{H}}_{22}{\mathrm{O}}_{11}$(sucrose) $+{\mathrm{H}}_2\mathrm{O}\underset{}{\overset{}{\to }}$ ${\mathrm{C}}_6{\mathrm{H}}_{12}{\mathrm{O}}_6$(Glucose) $+{\mathrm{C}}_6{\mathrm{H}}_{12}{\mathrm{O}}_6$(Fructose)

1. Here, Sucrose is a non-reducing sugar because it can't reduce the Tollen's reagent as it does not have a free carbonyl group.
2. However both glucose and fructose reduce Tollen's reagent gives silver mirror as they have a free carbonyl group. and thus a reducing sugar.

Explanation for incorrect options:

(A) Glucose is monosaccharides, so they can't be hydrolyzed. Hence option A is incorrect.

(B) Fructose is monosaccharides, so they can't be hydrolyzed. Hence option B is incorrect.

(D) Galactose is monosaccharides, so they can't be hydrolyzed. Hence option D is incorrect.

So, option (C) is correct.