Which of the following correctly identifies the functional group present in ${\mathrm{CH}}_3-\mathrm{COOH}$?

• A. Carboxylic acid
• B. Ketone
• C. Aldehyde
• D. Alcohol

Answer: (A)

Verified step by step guidance

1. Identify the molecular formula given: \(\mathrm{CH_3{-}COOH}\). This represents a molecule with a methyl group (\(\mathrm{CH_3}\)) attached to a \(\mathrm{COOH}\) group.
2. Recognize that the \(\mathrm{COOH}\) group is a combination of a carbonyl group (\(\mathrm{C=O}\)) and a hydroxyl group (\(\mathrm{-OH}\)) attached to the same carbon atom.
3. Recall the definitions of the functional groups: a carboxylic acid contains the \(\mathrm{-COOH}\) group, a ketone contains a carbonyl group (\(\mathrm{C=O}\)) bonded to two carbon atoms, an aldehyde contains a carbonyl group bonded to at least one hydrogen, and an alcohol contains a hydroxyl group (\(\mathrm{-OH}\)) bonded to a saturated carbon.
4. Since the molecule has the \(\mathrm{-COOH}\) group, which includes both a carbonyl and hydroxyl group on the same carbon, it fits the definition of a carboxylic acid functional group.
5. Therefore, the correct identification of the functional group in \(\mathrm{CH_3{-}COOH}\) is carboxylic acid.