14.16      How do you explain the amphoteric behaviour of amino acids?

Amino acid has both acidic group  $\dpi{80} (C=O)\left$  and basic group $\dpi{80} (N-H)$. Thus in aqueous solution, the carboxyl group can lose a proton and the basic group (amine group) can accept a proton. In this way, it forms zwitter ion which can act in both ways i.e., acidic as well as basic. Hence amino acids are amphoteric in nature.