Question

Given below are two statements: Statement-I: Methane can be prepared by decarboxylation of sodium acetate, by Kolbe’s electrolysis, and by \( \text{CH}_3\text{MgBr} \).
Statement-II: Methane can’t be prepared by unsaturated hydrocarbon and by Wurtz reaction. Choose the correct option:

• A. Statement-I and Statement-II both are correct.
• B. Statement-I and Statement-II both are incorrect.
• C. Statement-I is correct but Statement-II is incorrect.
• D. Statement-I is incorrect but Statement-II is correct.

Answer 1

The Correct Option is D

Step 1: Understanding the Question:
The question tests various organic preparation methods specifically for Methane (\(CH_4\)), the simplest alkane.
Step 2: Detailed Explanation:
Statement-I:
- Decarboxylation of sodium acetate (\(CH_3COONa + NaOH \xrightarrow{CaO, \Delta} CH_4\)) works.
- Kolbe’s electrolysis of sodium acetate gives Ethane (\(C_2H_6\)) at the anode, not Methane.
- \(CH_3MgBr\) reacting with water/alcohol (\(H^+\) source) gives Methane.
Since Kolbe's electrolysis fails to produce methane, Statement-I is overall incorrect.

Statement-II:
- Unsaturated hydrocarbons (alkenes/alkynes) have at least 2 carbons. Hydrogenation of these will produce alkanes with 2 or more carbons. Thus, methane cannot be prepared from them.
- Wurtz reaction involves coupling of two alkyl groups (\(R-X + 2Na + X-R \to R-R\)). The smallest product possible is Ethane (\(CH_3-CH_3\)). Thus, methane cannot be prepared by the Wurtz reaction.
Statement-II is correct.
Step 3: Final Answer:
Statement-I is incorrect and Statement-II is correct.