Question

Which of the following represents the conjugate pair of $N{{H}_{3}}$?
A. \[N{{H}_{2}}^{-}\]
B. \[N{{H}_{4}}^{+}\]
C. Both (a) and (b)
D. \[{{N}^{3-}}\]

Answer 1

Hint: Conjugate base is the compound formed when the given compound loses a hydrogen ion. Conjugate acid is the compound which is formed when the given compound gains a hydrogen ion.

Complete step by step answer:
$N{{H}_{3}}$is the compound which can be considered as a base and an acid too. So if we consider this compound firstly as a base then it will gain a hydrogen ion and will form a conjugate acid. So the following reaction will make you understand the formation of conjugate acid of $N{{H}_{3}}$
\[N{{H}_{3}}\xrightarrow{+{{H}^{+}}ion}N{{H}_{4}}^{+}\]
$\text{(acid) (conjugate base)}$
Now we will consider $N{{H}_{3}}$as an acid then it will lose a hydrogen ion and will form a conjugate base. So the following reaction will make you understand the formation of conjugate base of $N{{H}_{3}}$
\[N{{H}_{3}}\xrightarrow{-{{H}^{+}}ion}N{{H}_{2}}^{-}\]
$\text{(base) (conjugate acid)}$
So the correct answer for this question is option c'. the gain and loss of one hydrogen ion only makes so much difference that the compound is changed to a conjugate acid and a conjugate base.

So, the correct answer is Option C .

Note: Students generally don’t remember the concept of conjugate base and conjugate acid. They forget that in which reaction the hydrogen ion is gained and in which hydrogen ion is closed. One should always write the equations to gain marks.

The conjugate base of strong acids are weak such as HCl because they donate their proton readily and easily and there is essentially no tendency for conjugate base chlorine ions to re accept a proton. A strong base is one which holds the hydrogen ion firmly and accepts it such that there is no tendency for the conjugate acid to donate a proton.