A: Electrolysis of molten calcium hydride produces hydrogen gas at the cathode.
R: Hydrogen in calcium hydride is present as `H^(+)` ion.

Options

A. If both Assertion & Reason are true and the reason is the correct explanation of the assertion, then mark (1)
B. If both Assertion & Reason are true but the reason is not the correct explanation of the assertion, then mark (2)
C. If Assertion is true statement but Reason is false, then mark (3)
D. If both Assertion and Reason are false statements then mark (4)

Answer

To solve the question regarding the electrolysis of molten calcium hydride, we will analyze both the assertion and the reason provided.

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that "Electrolysis of molten calcium hydride produces hydrogen gas at the cathode."
- In electrolysis, reduction occurs at the cathode and oxidation occurs at the anode.

2. **Electrolysis of Calcium Hydride**:
- When molten calcium hydride (CaH₂) undergoes electrolysis, it dissociates into calcium ions (Ca²⁺) and hydride ions (H⁻).
- The reactions occurring during electrolysis are:
- At the **cathode**: Reduction occurs. The calcium ions (Ca²⁺) gain electrons to form solid calcium (Ca).
\[ \text{Ca}^{2+} + 2e^- \rightarrow \text{Ca} \]
- At the **anode**: Oxidation occurs. The hydride ions (H⁻) lose electrons to form hydrogen gas (H₂).
\[ 2\text{H}^- \rightarrow \text{H}_2 + 2e^- \]

3. **Analyzing the Assertion**:
- From the reactions above, we see that hydrogen gas is produced at the anode, not at the cathode. Therefore, the assertion is **false**.

4. **Understanding the Reason**:
- The reason states that "Hydrogen in calcium hydride is present as H⁺ ion."
- In reality, in calcium hydride, hydrogen is present as hydride ions (H⁻), not as H⁺ ions. Therefore, this statement is also **false**.

5. **Conclusion**:
- Since both the assertion and the reason are false, the correct answer is option 4: "Both assertion and reason are false statements."