Question

Conjugate acid of $N{{H}_{2}}^{-}$ is:
(a)-\[N{{H}_{3}}\]
(b)-\[N{{H}_{4}}^{+}\]
(c)- \[{{N}^{-}}\]
(d)-\[N{{H}_{2}}^{+}\]

Answer 1

Hint: The inverse of the definition of acid and base. This is a pair. It is an inorganic substance that can be found in air, soil, water, etc. It is normally gas at room temperature.

Complete answer:
Let us first understand the concept of acid and base.
An acid is defined as a substance that tends to give a proton (${{H}^{+}}$ ) and a base is defined as a substance that tends to accept a proton.
An acid is a proton donor whereas a base is a proton acceptor.
So, the acid-base pairs are called conjugate acid-base pairs.
A conjugate pair of acid and a base differs by a proton only.
Simply, we can write,
\[\text{Conjugate acid}\rightleftharpoons \text{Conjugate base + }{{\text{H}}^{\text{+}}}\]
Conjugate acid = base +${{H}^{+}}$ and conjugate base = acid -${{H}^{+}}$ .
So, we have to know the conjugate acid of :
For conjugate acid we have to add ${{\text{H}}^{\text{+}}}$ :
Hence, $N{{H}^{-}}_{2}+{{H}^{+}}\to N{{H}_{3}}$
So, the correct option is (a)-$N{{H}_{3}}$
So, the correct answer is “Option A”.

Additional Information:
Let us know the conjugate acid-base pairs of other options:
(b)-$N{{H}_{4}}^{+}$ is the conjugate acid of $N{{H}_{3}}$
(c)-${{N}^{-}}$ is the conjugate base of $N{{H}^{-}}$
(d)- $N{{H}_{2}}^{+}$ is the conjugate base of $N{{H}_{3}}$

Note: The concept of conjugate acid-base helps to know the basic character of some compounds which do not have $O{{H}^{-}}$ a group. It explains the acid-base reactions in the non-aqueous medium. It tells the ionic species also act as acid or base. You could get confused between the addition or subtraction of ${{H}^{+}}$ to get the result.