Assertion : Electrolysis of molten `CaH_2` produces hydrogen gas at anode.
Reason : In `CaH_2`, hydrogen is present in the form of hydride `H^(−)`.

Options

A. Both Assertion and Reason are true and Reason is the correct explanation of Assertion
B. Both Assertion and Reason are true and Reason is not the correct explanation of Assertion
C. Assertion is true but Reason is false
D. Both Assertion and Reason are false

Answer

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

### Step-by-Step Solution:

1. **Understanding the Electrolysis of CaH₂**:
- When molten calcium hydride (CaH₂) undergoes electrolysis, it dissociates into its constituent ions:
\[ \text{CaH}_2 \rightarrow \text{Ca}^{2+} + 2\text{H}^{-} \]

2. **Identifying the Electrodes**:
- In electrolysis, the cathode is the negatively charged electrode where reduction occurs, and the anode is the positively charged electrode where oxidation occurs.
- The positively charged ion (\(\text{Ca}^{2+}\)) will migrate to the cathode, while the negatively charged ion (\(\text{H}^{-}\)) will migrate to the anode.

3. **Reactions at the Electrodes**:
- **At the Cathode**:
- The calcium ions (\(\text{Ca}^{2+}\)) will gain electrons (reduction) to form calcium metal:
\[ \text{Ca}^{2+} + 2e^{-} \rightarrow \text{Ca} \]
- **At the Anode**:
- The hydride ions (\(\text{H}^{-}\)) will lose electrons (oxidation) to form hydrogen gas:
\[ 2\text{H}^{-} \rightarrow \text{H}_2 + 2e^{-} \]

4. **Evaluating the Assertion**:
- The assertion states that electrolysis of molten \(\text{CaH}_2\) produces hydrogen gas at the anode. Based on the reaction at the anode, this statement is true.

5. **Evaluating the Reason**:
- The reason states that in \(\text{CaH}_2\), hydrogen is present in the form of hydride \(\text{H}^{-}\). This is also true, as the dissociation of \(\text{CaH}_2\) produces \(\text{H}^{-}\) ions.

6. **Conclusion**:
- Both the assertion and the reason are true, and the reason correctly explains the assertion. Therefore, the correct answer is:
- **Both assertion and reason are true. Reason is the correct explanation of assertion.**

### Final Answer:
**Option A: Both assertion and reason are true. Reason is the correct explanation of assertion.**

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