Question

Which one of the following aqueous solutions of salts has the lowest $pH$ value?

• A. $C{H}_{3}COONa$
• B. $NaCl$
• C. $N{H}_{4}OOCC{H}_3$
• D. $N{H}_{4}Cl$

Answer 1

The correct option is D $N{H}_{4}Cl$

$N{H}_{4}Cl$ is a salt of weak base $\left(N{H}_{4}OH\right)$ and strong acid $\left(HCl\right)$, thus undergoes cationic hydrolysis and provides $H^{+}$ ions that make the solution acidic i.e., $pH$ is very less or less than $7$.

$N{H}_{4}Cl+H_{2}O\to N{H}_{4}OH+HCl$

"or"

$N{H}_4^{+}+H_{2}O\to N{H}_{4}OH+H^{+}$.