Assertion : Coefficient of performance in refrigrator may be greater than one.
Reason : Heat extracted from lower temperature reservoir.

Answer

To solve the question regarding the assertion and reason about the coefficient of performance (COP) in a refrigerator, let's break it down step by step.

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that the coefficient of performance (COP) in a refrigerator may be greater than one.
- The COP is defined as the ratio of heat extracted from the cold reservoir (Q2) to the work input (W) required to extract that heat.
- Mathematically, COP = Q2 / W.
- It is possible for COP to be greater than 1 if the heat extracted (Q2) is greater than the work input (W).

2. **Understanding the Reason**:
- The reason states that heat is extracted from a lower temperature reservoir.
- In refrigeration cycles, heat is indeed extracted from a cold reservoir (lower temperature) and rejected to a hot reservoir (higher temperature).
- This process involves doing work on the system (compressing the refrigerant).

3. **Analyzing the Relationship**:
- When a refrigerator operates, it removes heat (Q2) from the cold space and transfers it to the hot space, requiring work (W) to do so.
- The relationship can be expressed as Q1 = Q2 + W, where Q1 is the heat rejected to the hot reservoir.

4. **Conclusion on Assertion and Reason**:
- The assertion is true: COP can be greater than 1.
- The reason is also true: heat is extracted from a lower temperature reservoir.
- However, the reason does not fully explain why the assertion is true. The assertion's truth relies on the relationship between Q2 and W, not merely on the fact that heat is extracted from a lower temperature reservoir.

5. **Final Evaluation**:
- Therefore, the assertion is true, and the reason is true, but the reason is not the correct explanation for the assertion.

### Summary:
- **Assertion**: True
- **Reason**: True, but not the correct explanation for the assertion.