Which functional group is characteristic of an amine?

• A. A hydroxyl group ($OH$)
• B. A carbonyl group ($C=O$)
• C. An amino group ($N{H}_2$)
• D. A carboxyl group ($C=O$ and $OH$ on the same carbon)

Answer: (C)

Verified step by step guidance

1. Understand that functional groups are specific groups of atoms within molecules that are responsible for the characteristic chemical reactions of those molecules.
2. Identify the functional groups listed: hydroxyl group (–OH), carbonyl group (C=O), amino group (–NH₂), and carboxyl group (–COOH, which is a combination of a carbonyl and hydroxyl group on the same carbon).
3. Recall that an amine is an organic compound derived from ammonia (NH₃) where one or more hydrogen atoms are replaced by alkyl or aryl groups, and its characteristic functional group is the amino group (–NH₂).
4. Recognize that the amino group contains a nitrogen atom bonded to hydrogen atoms, which distinguishes it from the hydroxyl (oxygen and hydrogen), carbonyl (carbon double bonded to oxygen), and carboxyl groups (carbonyl plus hydroxyl on the same carbon).
5. Conclude that the functional group characteristic of an amine is the amino group (–NH₂).