Which class of compounds has the functional group \(-\mathrm{COOH}\)?
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → Carboxylic acids
The carboxyl group \(-\mathrm{COOH}\) is the functional group of carboxylic acids; ethanoic acid (acetic acid, \(\mathrm{CH_3COOH}\)), the acid in vinegar, is an example.
Why the other options are incorrect
Option (1) Ketones — Incorrect. Ketones have a C=O group joined to two carbon atoms, as in acetone.
Option (2) Alkanes — Incorrect. Alkanes are hydrocarbons with only single bonds and no functional group.
Option (3) Aldehydes — Incorrect. Aldehydes have the \(-\mathrm{CHO}\) group, as in methanal (formaldehyde).