Question

Which will undergo cationic hydrolysis?
A.NaCl
B.${\text{C}}{{\text{H}}_3}{\text{COONa}}$.
C.${\left( {{\text{N}}{{\text{H}}_4}} \right)_2}{\text{S}}{{\text{O}}_4}$
D.${{\text{H}}_2}{\text{C}}{{\text{O}}_{\text{3}}}$

Answer 1

Hint: Those salts undergo cationic hydrolysis which are composed of strong acid and weak base. Check each given species whether it is produced from strong acid and weak base or not.
Step-by-step answer:
Salts which are made from strong acid and weak base undergo cationic hydrolysis. Cationic hydrolysis of such salts leads to the formation of acidic solutions.
Strong acids are those acids which undergo complete dissociation in the aqueous solution while weak acids are those acids which undergo partial dissociation (not fully dissociated) in the aqueous solution.
Similarly, strong bases are those bases which undergo complete dissociation in the aqueous solution while weak bases are those bases which undergo partial dissociation (not fully dissociated) in the aqueous solution.
Sodium chloride (NaCl) is a salt of strong acid (HCl) and strong base (NaOH) as shown below.
${\text{NaCl}} + {{\text{H}}_{\text{2}}}{\text{O}} \rightleftharpoons {\text{NaOH}} + {\text{HCl}}$
Thus it will not undergo cationic hydrolysis.
Sodium acetate $\left( {{\text{C}}{{\text{H}}_3}{\text{COONa}}} \right)$ is a salt of weak acid $\left( {{\text{C}}{{\text{H}}_{\text{3}}}{\text{COOH}}} \right)$ and strong base (NaOH) as shown below.
${\text{C}}{{\text{H}}_{\text{3}}}{\text{COONa}} + {{\text{H}}_{\text{2}}}{\text{O}} \rightleftharpoons {\text{C}}{{\text{H}}_{\text{3}}}{\text{COOH}} + {\text{NaOH}}$
Thus it will not undergo cationic hydrolysis.
Ammonium sulphate $\left( {{{\left( {{\text{N}}{{\text{H}}_4}} \right)}_2}{\text{S}}{{\text{O}}_4}} \right)$ is a salt of strong acid $\left( {{{\text{H}}_{\text{2}}}{\text{S}}{{\text{O}}_4}} \right)$ and weak base $\left( {{\text{N}}{{\text{H}}_{\text{3}}}} \right)$. Thus it will undergo cationic hydrolysis to produce an acidic solution.
${\left( {{\text{N}}{{\text{H}}_4}} \right)_2}{\text{S}}{{\text{O}}_4} + 2{{\text{H}}_{\text{2}}}{\text{O}} \rightleftharpoons 2{\text{N}}{{\text{H}}_{\text{4}}}{\text{OH}} + {{\text{H}}_2}{\text{S}}{{\text{O}}_{\text{4}}}$
Carbonic acid $\left( {{{\text{H}}_2}{\text{C}}{{\text{O}}_{\text{3}}}} \right)$ is not a salt. It is a weak acid. Thus it cannot undergo cationic hydrolysis.

Note: Do not get confused between cationic hydrolysis and anionic hydrolysis. Cationic hydrolysis shown by salts consisting of strong acid and weak base components. Such salts produce acidic solutions. On the other hand anionic hydrolysis shown by salts consists of strong base and weak acid. Such salts produce basic solutions.