Concept:The hydrolysis of a nitrile containing "n" carbon atoms always yields a carboxylic acid with the exact same number of "n" carbon atoms.
Formula:$$ \text{CH}_3\text{C}\equiv\text{N} + 2\text{H}_2\text{O} \xrightarrow{\text{H}^+ / \text{OH}^-} \text{CH}_3\text{COOH} + \text{NH}_3 \text{ (or } \text{NH}_4^+ \text{)} $$
Solution:- Methyl cyanide (\( \text{CH}_3\text{CN} \)), also known as acetonitrile, contains 2 carbon atoms.
- Upon complete hydrolysis, the \(-\text{CN}\) group transforms into a \(-\text{COOH}\) group.
- The resulting 2-carbon carboxylic acid is acetic acid (ethanoic acid).
Why other options are incorrect:Formic acid has 1 carbon, propanoic acid has 3 carbons, and butanoic acid has 4 carbons. None of these match the 2-carbon skeleton of methyl cyanide.
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