Assertion : Calcium carbide on hydrolysis gives methane.
Reason : Calcium carbide contains `C_2^(2–)` anion.

Options

A. If both A and R are true and R is the correct explanation for A.
B. If both A and R are true and R is not the correct explanation for A.
C. If A is true and R is false.
D. If A is false and R is true.

Answer

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

### Step 1: Analyze the Assertion
The assertion states: "Calcium carbide on hydrolysis gives methane."

- Calcium carbide (CaC2) is a compound that, when hydrolyzed, reacts with water. The reaction can be written as:
\[ \text{CaC}_2 + 2 \text{H}_2\text{O} \rightarrow \text{Ca(OH)}_2 + \text{C}_2\text{H}_2 \]
- The product of this reaction is calcium hydroxide (Ca(OH)2) and acetylene (C2H2), not methane (CH4).

**Conclusion for Step 1**: The assertion is **false** because calcium carbide does not produce methane upon hydrolysis.

### Step 2: Analyze the Reason
The reason states: "Calcium carbide contains C2^(2–) anion."

- Calcium carbide (CaC2) indeed contains the C2^(2–) anion. The calcium ion (Ca^2+) balances the charge of the C2^(2–) anion in the compound.
- Therefore, the presence of the C2^(2–) anion in calcium carbide is correct.

**Conclusion for Step 2**: The reason is **true** because calcium carbide does contain the C2^(2–) anion.

### Final Conclusion
- The assertion is false, and the reason is true. Therefore, the correct answer is **Option D**: Assertion is false and reason is true.

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