Question

Sucrose, which is dextrorotatory in nature, after hydrolysis gives glucose and fructose, among which: 
(i) Glucose is laevorotatory and fructose is dextrorotatory.
(ii) Glucose is dextrorotatory and fructose is laevorotatory.
(iii) The mixture is laevorotatory.
(iv) Both are dextrorotatory.
 

• A. (i) and (iii)
• B. (iii) and (iv)
• C. (ii) and (iii)
• D. (iii) only

Hint:

Although sucrose is dextrorotatory, after hydrolysis, the mixture becomes laevorotatory due to fructose's stronger negative rotation.

Answer 1

The Correct Option is B

Step 1: Understanding the hydrolysis of sucrose. 
- Sucrose is dextrorotatory (\( +66^\circ \)), meaning it rotates plane-polarized light to the right. 
- Upon hydrolysis, it yields glucose and fructose. 
Step 2: Identifying the optical rotation of products. 
- Glucose is dextrorotatory (\( +52.5^\circ \)). 
- Fructose is laevorotatory (\( -92^\circ \)). 
Step 3: Determining the optical rotation of the mixture. 
- Since fructose has a higher magnitude of rotation than glucose, the mixture is net laevorotatory. 
- Hence, statements (iii) and (iv) are correct.