Question

Statement-I: Sucrose is dextrorotatory and upon hydrolysis, it becomes laevorotatory. Statement-II: Sucrose on hydrolysis gives glucose and fructose such that the laevorotation of glucose is more than dextrorotation of fructose. Which of the following is correct?

• A. Both Statement-I and Statement-II are correct
• B. Both Statement-I and Statement-II are incorrect
• C. Statement-I is correct, Statement-II is incorrect
• D. Statement-II is correct, Statement-I is incorrect

Hint:

When dealing with optical rotation, remember that the net rotation is the sum of the individual rotations of the components.

Answer 1

The Correct Option is C

To determine the correctness of the given statements and understand the nature of sucrose upon hydrolysis, let's analyze each statement step by step:

Statement-I: Sucrose is dextrorotatory and upon hydrolysis, it becomes laevorotatory.

Sucrose is indeed dextrorotatory, meaning it rotates plane-polarized light to the right. It is composed of one molecule of glucose and one molecule of fructose. Upon hydrolysis, sucrose breaks down into glucose and fructose.

Both glucose and fructose have their optical activities; glucose is dextrorotatory, and fructose is laevorotatory. However, the laevorotation of fructose is greater than the dextrorotation of glucose, which results in an overall laevorotatory mixture after hydrolysis, indicating an inversion of optical rotation.

Thus, Statement-I is correct.

Statement-II: Sucrose on hydrolysis gives glucose and fructose such that the laevorotation of glucose is more than dextrorotation of fructose.

This statement claims that the laevorotary effect from glucose is greater than the dextrorotatory influence from fructose, which would result in a net dextrorotatory effect after hydrolysis. However, this is incorrect. The actual laevorotary effect from fructose is indeed stronger than the dextrorotary effect from glucose, resulting in an overall laevorotatory solution (also explaining the "invert sugar" phenomenon).

Therefore, Statement-II is incorrect.

Conclusion:

The correct answer is that Statement-I is correct, Statement-II is incorrect.