At pH 4, glycine exists as

Options

A. `H_3 overset(+)N -CH_2-COO^-`
B. `H_3 overset(+)N - CH_2 -COOH`
C. `H_2 N - CH_2 - COOH`
D. `H_2 N - CH_2 - COO^-`

Answer

B

Explanation

At pH = 4 (i.e. acidic medium), an amphoteric Zwitter ion structure changes into cation when an acid is added to it.
`underset(""^(o+)NH_3)underset(|)R-CH-COO^(-) + H^+ to underset(""^(o+)NH_3)underset(|)R-CH-COOH`