Question

Assertion : Hydrolysis of sucrose brings about a change in sign of rotation from dextro to laevo.
Reason : Hydrolysis always changes the optical rotation of a compound.

• A. If both assertion and reason are true and reason is the correct explanation of assertion.
• B. If both assertion and reason are true but reason is not the correct explanation of assertion.
• C. If assertion is true but reason is false.
• D. If both assertion and reason are false.

Answer 1

Answer: (C)

Sucrose is dextrorotatory but after hydrolysis gives dextrorotatory glucose and laevorotatory fructose. Since laevorotation of fructose $(- 92.4^{\circ})$ is more than dextrorotation of glucose $(+52.5^{\circ})$, hence the mixture is laevorotatory.