Assertion : According to Le-Chatelier's principle, addition of heat to an equilibrium solid `hArr` liquid results in decrease in the amount of solid.
Reason : Reaction is endothermic, so on heating forward reaction is favoured.

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 solve the question regarding the assertion and reason related to Le-Chatelier's principle, we can break it down into a step-by-step explanation.

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that adding heat to an equilibrium between a solid and a liquid results in a decrease in the amount of solid.
- This is based on the principle that when a system at equilibrium is subjected to a change (in this case, the addition of heat), the system will adjust to counteract that change.

2. **Identifying the Reaction**:
- The reaction can be represented as:
\[ \text{Solid} \rightleftharpoons \text{Liquid} \]
- In this scenario, the solid is converting into a liquid.

3. **Applying Le-Chatelier's Principle**:
- According to Le-Chatelier's principle, if heat is added to an endothermic reaction, the equilibrium will shift towards the products to absorb the added heat.
- Since the conversion of solid to liquid requires heat (endothermic), adding heat will favor the forward reaction (solid to liquid).

4. **Conclusion from the Assertion**:
- As a result of the equilibrium shifting towards the liquid phase, the amount of solid will decrease.
- Therefore, the assertion is correct.

5. **Understanding the Reason**:
- The reason states that the reaction is endothermic, which means it absorbs heat.
- This supports the assertion because if the forward reaction (solid to liquid) is favored by the addition of heat, it confirms that the amount of solid will decrease.

6. **Final Evaluation**:
- Both the assertion and the reason are true, and the reason correctly explains the assertion.
- Thus, the correct conclusion is that both statements are true, and the reason is valid.

### Final Answer:
- Both the assertion and the reason are true, and the reason correctly explains the assertion.