Question

Consider the reaction below.

Answer 1

Wrong answer.  s/b H2O and H3O+

Answer 2

Answer : The correct option is $H_2O\text{ and }H_3O^+$

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.

The given equilibrium reaction will be,

$H_2PO_4^-+H_2O\rightleftharpoons H_3O^++HPO_4^{2-}$

In this reaction, $H_2PO_4^-$ and $H_2O$ are acid and base and $H_3O^+$ and $HPO_4^{2-}$ are conjugate acid and base respectively.

From this we conclude that, $H_2O\text{ and }H_3O^+$ is a base-conjugate acid pair.

Hence, the correct option is $H_2O\text{ and }H_3O^+$