In which of the following salts only cationic hydrolysis is involved ?

Options

A. `CH_3COONH_4`
B. `CH_3COONa`
C. `NH_4Cl`
D. `Na_2SO_4`

Answer

To determine which of the given salts involves only cationic hydrolysis, we need to analyze each option based on the nature of the acid and base from which they are derived.

### Step-by-Step Solution:

1. **Understand Hydrolysis Types**:
- Cationic hydrolysis occurs when a salt is formed from a strong acid and a weak base. In this case, the cation (from the weak base) undergoes hydrolysis.
- Anionic hydrolysis occurs when a salt is formed from a weak acid and a strong base. Here, the anion (from the weak acid) undergoes hydrolysis.

2. **Analyze Each Option**:
- **Option 1: CH3COONH4 (Ammonium Acetate)**:
- This salt is formed from acetic acid (weak acid) and ammonium hydroxide (weak base).
- Since both components are weak, it does not involve only cationic hydrolysis.

- **Option 2: CH3COONa (Sodium Acetate)**:
- This salt is formed from acetic acid (weak acid) and sodium hydroxide (strong base).
- Here, the anion (acetate) would undergo hydrolysis, not cationic hydrolysis.

- **Option 3: NH4Cl (Ammonium Chloride)**:
- This salt is formed from hydrochloric acid (strong acid) and ammonium hydroxide (weak base).
- Since it is a salt of a strong acid and a weak base, it will undergo cationic hydrolysis. Thus, this option is correct.

- **Option 4: Na2SO4 (Sodium Sulfate)**:
- This salt is formed from sulfuric acid (strong acid) and sodium hydroxide (strong base).
- Since both components are strong, there is no hydrolysis involved.

3. **Conclusion**:
- The only salt that involves only cationic hydrolysis is **NH4Cl (Ammonium Chloride)**.

### Final Answer:
**NH4Cl (Ammonium Chloride)** is the correct answer.

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