Question 51

Given below are two statements:

Statement I: Sucrose is dextrorotatory. However, sucrose upon hydrolysis gives a solution having mixture of products. This solution shows laevorotation.

Statement II : Hydrolysis of sucrose gives glucose and fructose. Since the laevorotation of glucose is more than the dextrorotation of fructose, the resulting solution becomes laevorotato1y.

In the light of the above statements, choose the correct answer from the options given below

We need to evaluate the two statements about sucrose and its hydrolysis.

Sucrose is indeed dextrorotatory with specific rotation $$[\alpha] = +66.5°$$. Upon hydrolysis, sucrose gives an equimolar mixture of glucose and fructose. The mixture is called invert sugar and is laevorotatory because fructose has a larger magnitude of laevorotation ($$-92°$$) compared to the dextrorotation of glucose ($$+52.5°$$).

Statement I is true.

Statement II says "the laevorotation of glucose is more than the dextrorotation of fructose." This is incorrect. Glucose is dextrorotatory ($$+52.5°$$), not laevorotatory. Fructose is laevorotatory ($$-92°$$). The statement has swapped the optical activities of glucose and fructose.

The correct explanation is: the laevorotation of fructose ($$-92°$$) is more than the dextrorotation of glucose ($$+52.5°$$), making the mixture laevorotatory.

Statement II is false.

Statement I is true but Statement II is false, which matches Option C.

Therefore, the answer is Option C.

Create a FREE account and get:

  • Free JEE Mains Previous Papers PDF
  • Take JEE Mains paper tests