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: Analyzing Statement-I.
Statement-I says that methane can be prepared by: - Decarboxylation of sodium acetate: This is a correct method for preparing methane. Decarboxylation of sodium acetate (using soda-lime) produces methane. - Kolbe’s electrolysis: This method involves electrolysis of sodium salts of carboxylic acids, which also leads to the formation of methane. - \( \text{CH}_3\text{MgBr} \): Reacting methyl magnesium bromide (\( \text{CH}_3\text{MgBr} \)) with water yields methane. Thus, Statement-I is correct in listing methods for preparing methane. However, the statement in the question has a mistake because it implies that the preparation of methane can be done only by these methods, but there are additional methods such as the Wurtz reaction. Therefore, this statement is somewhat misleading and incorrect because it excludes other methods.
Step 2: Analyzing Statement-II.
Statement-II claims that methane can’t be prepared by unsaturated hydrocarbons and by the Wurtz reaction. This is incorrect. - Wurtz reaction: The Wurtz reaction involves the reaction of alkyl halides with sodium metal to form alkanes. When ethyl chloride undergoes a Wurtz reaction, it produces ethane. Similarly, methane can be prepared by the Wurtz reaction using methyl halides. - Unsaturated hydrocarbons: Methane can indeed be obtained from unsaturated hydrocarbons by hydrogenation, where an alkene like ethene reacts with hydrogen in the presence of a catalyst to form ethane, and further, methane can be produced from certain alkenes under specific conditions. Thus, Statement-II is incorrect, as methane can be prepared by unsaturated hydrocarbons and by the Wurtz reaction.
Step 3: Conclusion.
Since Statement-I is misleading and Statement-II is incorrect, the correct answer is: \[ \text{(D) Statement-I is incorrect but Statement-II is correct.} \]
Final Answer: (D) Statement-I is incorrect but Statement-II is correct.