Final answer:
The NH2 group is present in amine compounds. Amines are derivatives of ammonia where at least one hydrogen is replaced by a hydrocarbon group and amino acids contain both an amine group and a carboxyl group.
Step-by-step explanation:
The group present in amine compounds is the NH2 group.
In chemistry, an amine is an organic compound derived from ammonia (NH3) where one or more hydrogen atoms are replaced by a hydrocarbon. For example, replacing one hydrogen from NH3 with an alkyl group results in a primary amine, RNH2. Further, amino acids are a specific class of compounds that contain both an amine group and a carboxyl group (-COOH). However, in the context of the student's question, we're focusing on the characteristic functional group of amines which is the amino group, -NH2.