Assertion`:` A solution of sucrose in water is dextrorotatory. But on hydrolysis in the presence of a little hydrochloric acid, it becomes laevaorotatory.
Reason `:` Sucrose on hydrolysis gives unequal amounts of glucose and fructose. As a result of this, change in sign of rotation is observed.

Options

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

Explanation

To solve the question, we need to analyze both the assertion and the reason provided.

### Step 1: Understanding the Assertion
The assertion states that a solution of sucrose in water is dextrorotatory, but upon hydrolysis in the presence of hydrochloric acid, it becomes levorotatory.

- **Dextrorotatory** means that the substance rotates plane-polarized light to the right (clockwise), which is characteristic of sucrose.
- When sucrose undergoes hydrolysis, it breaks down into glucose and fructose.

### Step 2: Understanding the Reason
The reason given is that sucrose on hydrolysis gives unequal amounts of glucose and fructose, leading to a change in the sign of rotation.

- **Hydrolysis of sucrose**: Sucrose (C12H22O11) reacts with water (H2O) in the presence of an acid (like hydrochloric acid) to produce glucose (C6H12O6) and fructose (C6H12O6).
- The assertion claims that the amounts of glucose and fructose produced are unequal, which is incorrect. Hydrolysis of sucrose produces one mole of glucose and one mole of fructose.

### Step 3: Analyzing Optical Rotation
- The specific rotation of sucrose is approximately +66.5 degrees.
- The specific rotation of glucose is approximately +52 degrees.
- The specific rotation of fructose is approximately -92 degrees.

When sucrose is hydrolyzed:
- The average specific rotation of the resulting solution can be calculated as follows:
\[ \text{Average Specific Rotation} = \frac{(+52) + (-92)}{2} = \frac{-40}{2} = -20 \text{ degrees} \]
This indicates that the solution becomes levorotatory after hydrolysis.

### Step 4: Conclusion
- The assertion is true: Sucrose is dextrorotatory, and after hydrolysis, it becomes levorotatory.
- The reason is false: Sucrose hydrolysis produces equal amounts of glucose and fructose, not unequal amounts.

Thus, the final conclusion is that the assertion is true, but the reason is false.

### Final Answer
The assertion is true, and the reason is false.

---