Question

Given below are two statements
Assertion (A): Hydrolysis of sucrose results in change in the optical rotation from dextro (+) to laevo (–)
Reason (R): Both the products from the hydrolysis are leavorotatory

• A. Both A and R are correct and R is the correct explanation of A
• B. Both A and R are correct but R is not the correct explanation of A
• C. A is correct but R is incorrect
• D. A is incorrect but R is correct

Hint:

Hydrolysis of sucrose causes optical rotation to change from + to –, because fructose (–) dominates over glucose (+).

Answer 1

The Correct Option is C

Sucrose is dextrorotatory, but on hydrolysis, it yields glucose and fructose. While glucose is dextrorotatory, fructose is leavorotatory and has a higher magnitude of rotation. As a result, the mixture becomes leavorotatory—this is known as "inversion of sugar." However, the Reason given is incorrect because both products are not leavorotatory. Only fructose is leavorotatory, and it dominates due to its greater specific rotation.

Answer 2

Given below are two statements

Assertion (A): Hydrolysis of sucrose results in change in the optical rotation from dextro (+) to laevo (–)
Reason (R): Both the products from the hydrolysis are leavorotatory

Step 1: Understand what happens during hydrolysis of sucrose:
Sucrose is a disaccharide made up of glucose and fructose. In its original form, sucrose is dextrorotatory, meaning it rotates plane-polarized light toward the right (positive direction).

Upon hydrolysis (in the presence of dilute acid or the enzyme invertase), sucrose breaks down into glucose and fructose:
Sucrose + H₂O → Glucose + Fructose

Step 2: Analyze the optical properties of the products:
- Glucose is dextrorotatory
- Fructose is levorotatory, and its negative rotation is greater in magnitude than glucose’s positive rotation

Therefore, the net result after hydrolysis is that the optical rotation shifts from positive to negative — this is called inversion of optical rotation. Hence, the mixture is called invert sugar.

Step 3: Evaluate the given statements:
- Assertion (A) is correct because optical rotation does indeed shift from dextro to laevo.
- Reason (R) is incorrect because only fructose is levorotatory; glucose is dextrorotatory. So, it's incorrect to say both products are levorotatory.

Final Answer:
\[ \boxed{\text{A is correct but R is incorrect}} \]