JEE Advanced 2026 · Paper 2 · Chemistry Q9

ChemistryMultiple correct+4 / -1Question 45 of 54

The correct statement(s) regarding sugars is(are)

Given: Specific rotations of L-(−)-glucose and L-(+)-fructose are $-52.5^\circ$ and $+92.5^\circ$ , respectively.

On treatment with

\ce{HNO3}

, gluconic acid is oxidized to saccharic acid, whereas glucose is not oxidized to saccharic acid.

Fructose gives a positive Fehling's test because it isomerises to glucose and another aldohexose in the presence of Fehling's reagent.

Invert sugar is an equimolar mixture of D-glucose and D-fructose formed after hydrolysis of the corresponding disaccharide.

Specific rotation of invert sugar is

-40^\circ

Answer and worked solution

Official answer: B, C

(A) Nitric acid oxidises glucose itself to saccharic (glucaric) acid, oxidising both C1 and C6; gluconic acid is also oxidised to it. The claim that glucose is not oxidised is wrong. False.
(B) In the alkaline Fehling's solution, fructose isomerises through the enediol (Lobry de Bruyn-van Ekenstein) to glucose and mannose. These reduce $\ce{Cu^2+}$ . True.
(C) Hydrolysis of sucrose gives an equimolar mixture of D-glucose and D-fructose, called invert sugar. True.
(D) The D-sugars have rotations opposite to the L values given: D-glucose $+52.5^\circ$ , D-fructose $-92.5^\circ$ . Invert sugar: $\frac{52.5-92.5}2=-20^\circ$ , not $-40^\circ$ . False.

JEE Advanced 2026 · Paper 2, Chemistry question 9