Question

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

• A. $CH_{3}COONa$
• B. $NaCl$
• C. $NH_{4}OOCCH_{3}$
• D. $NH_{4}Cl$

Answer 1

Answer: (D)

$NH_{4}Cl$

Answer 2

$NH _{4} Cl$ is a salt of weak base
$\left( NH _{4} OH \right)$ and strong acid $( HCl )$,
thus undergoes cationic hydrolysis and provides
$H ^{+}$ions that make the solution acidic
$i e$, pH is very less or less than $7$ .
$NH _{4} Cl + H _{2} O \rightarrow NH _{4} OH + HCl$
or $NH _{4}^{+}+ H _{2} O \rightarrow NH _{4} OH + H ^{+}$