Amino acids are c A.



B.



C.



D.

Amino acids in which the number of –COOH and –NH2 groups are equal are called neutral amino acids. In (i) and (iii) each contains an equal number of -COOH and –NH2 group. So both (i) and (iii) are incorrect.

Acidic amino acids are those in which the number of –COOH groups are more than –NH2 groups.

In both amino acids (ii) and (iv), number of –COOH groups and –NH2 group is 2 and 1 respectively. So they are acidic amino acids.Therefore options (ii) and (iv) are correct.