Answer:
Option (e) is correct
Explanation:
According to definition of acid-conjugate base or base-conjugate acid pair-
if HA is an acid then [tex]A^{-}[/tex] is it's conjugate base
if B is a base then [tex]BH^{+}[/tex] is it's conjugate acid
a) HCN is an acid . So, [tex]CN^{-}[/tex] is it's conjugate base
b) [tex]NH_{3}[/tex] is a base. So, [tex]NH_{4}^{+}[/tex] is it's conjugate acid
c) Conjugate base of [tex]HPO_{4}^{2-}[/tex] is [tex]PO_{4}^{3-}[/tex]
d) [tex]SO_{4}^{2-}[/tex] is the conjugate base of [tex]HSO_{4}^{-}[/tex]
e) [tex]HAsO_{3}^{2-}[/tex] is the conjugate acid of [tex]AsO_{3}^{3-}[/tex]
So, option (e) is correct
