A : Methane cannot be prepared by kolbe electrolytic reaction.
R : In this reaction alkane is liberated at anode.

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, we need to analyze both the assertion (A) and the reason (R) provided:

**Assertion (A):** Methane cannot be prepared by Kolbe electrolytic reaction.
**Reason (R):** In this reaction, alkene is liberated at the anode.

### Step-by-Step Solution:

1. **Understanding Kolbe Electrolytic Reaction:**
- The Kolbe electrolytic reaction involves the electrolysis of sodium or potassium salts of carboxylic acids. The general reaction can be represented as:
\[ RCOONa \xrightarrow{\text{Electrolysis}} R \cdots R + CO_2 + H_2 + \text{other products} \]
- Here, the carboxylate ion (RCOO⁻) is oxidized at the anode.

2. **Oxidation Process:**
- During the electrolysis, the carboxylate ion loses electrons (oxidation) to form a radical (R•) and carbon dioxide (CO₂):
\[ RCOO^- \rightarrow R• + CO_2 + e^- \]
- The radical (R•) can then dimerize to form alkenes or alkynes, depending on the structure of R.

3. **Formation of Methane:**
- Methane (CH₄) consists of only one carbon atom. In the Kolbe reaction, the dimerization process requires at least two carbon atoms to form a product. Therefore, it is impossible to generate methane directly from this reaction since it cannot be formed from a single radical.

4. **Analyzing the Reason:**
- The reason states that "alkene is liberated at the anode." This is partially correct because the dimerization of radicals can lead to the formation of alkenes, but it does not specifically explain why methane cannot be formed.

5. **Conclusion:**
- Both the assertion and the reason are true statements. However, the reason does not correctly explain the assertion. Thus, the correct conclusion is that while methane cannot be prepared by Kolbe electrolysis, the reason provided does not adequately justify this assertion.

### Final Answer:
Both assertion and reason are true, but the reason is not the correct explanation of the assertion.

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