Question

The conjugate acid of $N{H}_2^{⊝}$ is:

• A. $N{H}_3$
• B. $N{H}_{2}OH$
• C. $N{H}_4^{\oplus }$
• D. $N_2{H}_4$

Answer 1

The correct option is A $N{H}_3$

The concept of conjugate acid-base pair was given by Lowry-Bronsted Theory.
According to the theory, acids are proton $\left(H^{+}\right)$ donors while bases are proton $\left(H^{+}\right)$ acceptors.
Hence, in order to get the conjugate base of a species, we should consider that substance as an acid and vice versa.
For example,
$H_{2}S{O}_4\to HS{O}_4^{-}+H^{+}$
Therefore, conjugate base of $H_{2}S{O}_4$ is $HS{O}_4^{-}$.
Also,
$H_{2}P{O}_4^{-}\to HP{O}_4^{2-}+H^{+}$
Hence,
Conjugate acid of $HP{O}_4^{-2}$ is $H_{2}P{O}_4^{-}$.
Using this logic for above example,
$N{H}_2^{-}+H^{+}\to N{H}_3$
Conjugate acid of ${N{H}_2}^{-}$ is $N{H}_3$.