Which of the following amino acids contains nitrogen in its side chain but is classified as a neutral amino acid?

Step-by-step solution

Amino acids are classified as acidic, basic, or neutral depending upon the relative number of amino and carboxyl groups in their molecule. Equal number of amino and carboxyl groups makes it neutral; more number of amino than carboxyl groups makes it basic. Histidine, Arginine, and Lysine contain basic nitrogenous groups in their side chains, making them basic amino acids. Glutamine contains an amide group ( - CONH ₂ ) in its side chain. The nitrogen lone pair in an amide is involved in resonance with the carbonyl g