Answer : The option (d) is not a conjugate acid-base pair.
Explanation :
According to the Bronsted Lowry concept, Bronsted Lowry-acid is a substance that donates one or more hydrogen ion in a reaction and Bronsted Lowry-base is a substance that accepts one or more hydrogen ion in a reaction.
Or we can say that, conjugate acid is proton donor and conjugate base is proton acceptor.
(a) The equilibrium reaction will be,
[tex]NH_4^++OH^-\rightleftharpoons NH_3+H_2O[/tex]
In this reaction, [tex]NH_4^+/NH_3[/tex] are act as a conjugate acid-base.
(b) The equilibrium reaction will be,
[tex]H_3O^++OH^-\rightleftharpoons H_2O+H_2O[/tex]
In this reaction, [tex]H_3O^+/OH^-[/tex] are act as a conjugate acid-base.
(c) The equilibrium reaction will be,
[tex]H_2SO_3+OH^-\rightleftharpoons HSO_3^-+H_2O[/tex]
In this reaction, [tex]H_2SO_3/HSO_3^-[/tex] are act as a conjugate acid-base.
(d) The equilibrium reaction will be,
[tex]C_2H_3O_2^-+H_2O\rightleftharpoons HC_2H_3O_2+OH^-[/tex]
In this reaction, [tex]C_2H_3O_2^-/HC_2H_3O_2[/tex] are act as a conjugate base-acid.
Hence, from this we conclude that, the option (d) is not a conjugate acid-base pair but it is a act as conjugate base-acid.
