`alpha`-animo monocarboxylic acids have two `pk_a` values. Explain.

Explanation

One `pk_(a)` value arises from the dissociation of `R - CH (overset(oplus)(N)H_(3)) COOH` and second value arises from dissociation of `R - CH (NH_(2)) - COOH`.
`R - underset(underset(oplus NH_(3))(|))(CH) - COOH hArr R - underset(underset(NH_(2))(|))(CH) - COOH + H^(oplus) `
`R - underset(underset(NH_(2))(|))(CH) - COOH hArr R - underset(underset(NH_(2))(|))(CH) - COoverset(Θ)O + H^(oplus)`