Assertion:- If earth did not have atomosphere, its average surface temperature would be lower than what it is now.
Reason:- Greenhouse effect of the atmosphre would be absent, if earth did not have atmosphere.

Options

A. If both Assertion `&` Reason are True `&` the Reason is a correct explanation of the Assertion.
B. If both Assertion `&` Reason are True but Reason is not a correct explanation of the Assertion.
C. If Assertion is True but the Reason is False.
D. If both Assertion `&` Reason are False.

Answer

To analyze the given assertion and reason, we will break down the statements and evaluate their truthfulness step-by-step.

### Step 1: Understanding the Assertion
**Assertion:** If Earth did not have an atmosphere, its average surface temperature would be lower than what it is now.

- **Explanation:** The Earth's atmosphere plays a crucial role in regulating temperature through the greenhouse effect. Without an atmosphere, there would be no medium to trap heat, leading to a significant drop in average surface temperature.

### Step 2: Understanding the Reason
**Reason:** The greenhouse effect of the atmosphere would be absent if Earth did not have an atmosphere.

- **Explanation:** The greenhouse effect occurs because certain gases in the atmosphere (like CO2, CH4, and water vapor) trap heat from the Sun. Without these gases, the heat would escape back into space, and the greenhouse effect would not occur.

### Step 3: Evaluating the Relationship Between Assertion and Reason
- Both the assertion and reason are true statements. The assertion correctly states that the average surface temperature would be lower without an atmosphere, and the reason accurately describes the absence of the greenhouse effect in such a scenario.

### Conclusion
- **Final Evaluation:** Both the assertion and reason are true, but the reason does not provide a direct explanation for the assertion. Therefore, the correct answer is that both statements are true, but the reason is not the correct explanation for the assertion.

### Summary of the Solution
1. The assertion is true because the atmosphere contributes to the greenhouse effect, which keeps the Earth's temperature higher.
2. The reason is also true as the greenhouse effect relies on the presence of atmospheric gases.
3. However, the reason does not explain why the assertion is true; it merely states a fact about the atmosphere.