Identify the molecular formula or structure given: the group is represented as COOH.
Recall the common functional groups in organic chemistry and their characteristic formulas: Alcohol (-OH), Aldehyde (-CHO), Ketone (C=O within the carbon chain), and Carboxylic acid (-COOH).
Analyze the given group COOH: it contains a carbonyl group (C=O) and a hydroxyl group (-OH) attached to the same carbon atom.
Understand that the combination of a carbonyl and hydroxyl group on the same carbon defines the carboxylic acid functional group.
Conclude that the COOH group corresponds to the carboxylic acid functional group, not alcohol, aldehyde, or ketone.