$\mathrm{pH}$ of an aqueous solution of ${\mathrm{NH}}_4\mathrm{Cl}$ is

Step 1: Analyzing the given conditions

${\mathrm{NH}}_4\mathrm{Cl}$ (Ammonium chloride) is an acidic salt of strong acid (Hydrochloric acid) and weak base (Ammonium hydroxide).

Concentration of ${\mathrm{NH}}_4\mathrm{Cl}=0.1\mathrm{M}$

${\mathrm{pK}}_{\mathrm{b}}$=4.74

Step 2: Calculating the $\mathrm{pH}$ of the ${\mathrm{NH}}_4\mathrm{Cl}$ solution

The formula for the calculation of $\mathrm{pH}$ of salt of strong acid and weak base can be represented as:

$\mathrm{pH}$ &=$-\frac{1}{2}{\mathrm{logK}}_{\mathrm{w}}-\frac{1}{2}\mathrm{logC}+\frac{1}{2}{\mathrm{logK}}_{\mathrm{b}}$

$\mathrm{pH}$ &$=-\frac{1}{2}\log {10}^{(-14)}-\frac{1}{2}\log (0.1)+\frac{1}{2}\log (4.7)$

$\mathrm{pH}$ &=$7+0.5-0.3360$

$\mathrm{pH}$ &=7.163

Therefore, $\mathrm{pH}$ of an aqueous solution of $0.1{\mathrm{MNH}}_4\mathrm{Cl}$ solution is $7.163$

Hence the correct answer (B) >7