Arrange in order of increasing acidic strength

Options

A. `X gt Z gt Y`
B. `Z gt X gt Y`
C. `X gt Y gt Z`
D. `Z gt X gt Y`

Answer

A

Explanation

`pK_(a)` value of carboxylic group is less than `pK_(a)` of `overset(+)(N)H_(3)` in amino acid and `-overset(+)(N)H_(3)` (Z) will have comparatively less `pK_(a)` than `-overset(+)(N)H_(3)` (Y) due to -I effect of carboxylic group. We know that acidic strength is inversely proportional to `pK_(a)`. Hence, correct order of acidic strength is `-CO_(2)H_((X)) gt -overset(+)(N)H_(3(Z)) gt - overset(+)(N)H_(3(Y))`