Q18 / 150 · MHT CET 2026 (16 April Shift 2) · Chemistry
Which of the following salt undergoes anionic hydrolysis ?
- A$\text{CuSO}_4$
- Correct answerB$\text{Na}_2\text{CO}_3$
- C$\text{NH}_4\text{Cl}$
- D$\text{FeCl}_3$
Solution
Anionic hydrolysis occurs in salts formed by the neutralization of a strong base and a weak acid.
$\text{CuSO}_4$ is a salt of a weak base ($\text{Cu(OH)}_2$) and a strong acid ($\text{H}_2\text{SO}_4$). It undergoes cationic hydrolysis.
$\text{Na}_2\text{CO}_3$ is a salt of a strong base ($\text{NaOH}$) and a weak acid ($\text{H}_2\text{CO}_3$). The carbonate ion ($\text{CO}_3^{2-}$) undergoes anionic hydrolysis to produce $\text{OH}^-$ ions: $\text{CO}_3^{2-} + \text{H}_2\text{O} \rightleftharpoons \text{HCO}_3^- + \text{OH}^-$.
$\text{NH}_4\text{Cl}$ is a salt of a weak base ($\text{NH}_4\text{OH}$) and a strong acid ($\text{HCl}$). It undergoes cationic hydrolysis.
$\text{FeCl}_3$ is a salt of a weak base ($\text{Fe(OH)}_3$) and a strong acid ($\text{HCl}$). It undergoes cationic hydrolysis.
Thus, $\text{Na}_2\text{CO}_3$ undergoes anionic hydrolysis.
Answer: $\text{Na}_2\text{CO}_3$
$\text{CuSO}_4$ is a salt of a weak base ($\text{Cu(OH)}_2$) and a strong acid ($\text{H}_2\text{SO}_4$). It undergoes cationic hydrolysis.
$\text{Na}_2\text{CO}_3$ is a salt of a strong base ($\text{NaOH}$) and a weak acid ($\text{H}_2\text{CO}_3$). The carbonate ion ($\text{CO}_3^{2-}$) undergoes anionic hydrolysis to produce $\text{OH}^-$ ions: $\text{CO}_3^{2-} + \text{H}_2\text{O} \rightleftharpoons \text{HCO}_3^- + \text{OH}^-$.
$\text{NH}_4\text{Cl}$ is a salt of a weak base ($\text{NH}_4\text{OH}$) and a strong acid ($\text{HCl}$). It undergoes cationic hydrolysis.
$\text{FeCl}_3$ is a salt of a weak base ($\text{Fe(OH)}_3$) and a strong acid ($\text{HCl}$). It undergoes cationic hydrolysis.
Thus, $\text{Na}_2\text{CO}_3$ undergoes anionic hydrolysis.
Answer: $\text{Na}_2\text{CO}_3$
Hence, the correct answer is option: 'B'.