Assertion: A solution of sucrose in water is dextrorotatory but on hydrolysis in presence of little hydrochloric acid, it becomes laevorotatory.
Reason: Sucrose on hydrolysis gives unequal amounts of glucose and fructose as.

Options

A. If both 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 the assertion and reason both are false

Explanation

To analyze the assertion and reason provided in the question, we can break it down into a step-by-step solution.

### Step-by-Step Solution:

1. **Understanding Sucrose**:
- Sucrose is a disaccharide composed of glucose and fructose. It is known to be dextrorotatory, meaning it rotates plane-polarized light to the right.

2. **Dextrorotatory Nature of Sucrose**:
- When dissolved in water, sucrose exhibits dextrorotation due to its molecular structure.

3. **Hydrolysis of Sucrose**:
- When sucrose undergoes hydrolysis in the presence of water (H2O) and a catalyst like hydrochloric acid (HCl), it breaks down into its constituent monosaccharides: glucose and fructose.

4. **Formation of Glucose and Fructose**:
- The hydrolysis of sucrose produces glucose and fructose in a 1:1 ratio. However, glucose is dextrorotatory and fructose is levorotatory.

5. **Effect on Optical Activity**:
- The resulting mixture of glucose and fructose after hydrolysis will have different optical activities. The overall rotation of the solution will depend on the specific rotation values of glucose and fructose.

6. **Levorotatory Nature Post-Hydrolysis**:
- If the mixture of glucose and fructose results in a net rotation to the left (levorotation), this indicates that the levorotatory effect of fructose is stronger than the dextrorotatory effect of glucose in the mixture.

7. **Conclusion**:
- Therefore, the assertion that a solution of sucrose in water is dextrorotatory but becomes levorotatory upon hydrolysis is correct. The reason provided is also accurate, as the hydrolysis of sucrose yields glucose and fructose in a manner that results in a net levorotatory solution.

### Final Answer:
- **Assertion**: True
- **Reason**: True