Which of the following salts does not undergo hydrolysis ?

Options

A. `KCN`
B. `KCI`
C. `NH_(4)NO_(3)`
D. `FeCI_(3).6H_(2)O`

Explanation

To determine which of the given salts does not undergo hydrolysis, we need to analyze each salt based on the strength of the acids and bases from which they are derived. Hydrolysis occurs when a salt reacts with water to produce an acidic or basic solution.

### Step-by-Step Solution:

1. **Identify the Salts**: The salts given in the question are KCN, KCl, NH4NO3, and FeCl3.6H2O.

2. **Analyze KCN**:
- KCN is formed from KOH (a strong base) and HCN (a weak acid).
- Since KOH is a strong base and HCN is a weak acid, KCN will undergo hydrolysis, resulting in a basic solution.

3. **Analyze KCl**:
- KCl is formed from KOH (a strong base) and HCl (a strong acid).
- Both KOH and HCl are strong, which means KCl is a neutral salt. Therefore, KCl does not undergo hydrolysis.

4. **Analyze NH4NO3**:
- NH4NO3 is formed from NH4OH (a weak base) and HNO3 (a strong acid).
- Since NH4OH is a weak base and HNO3 is a strong acid, NH4NO3 will undergo hydrolysis, resulting in an acidic solution.

5. **Analyze FeCl3.6H2O**:
- FeCl3 is derived from Fe(OH)3 (a weak base) and HCl (a strong acid).
- Since Fe(OH)3 is a weak base and HCl is a strong acid, FeCl3 will also undergo hydrolysis, producing an acidic solution.

6. **Conclusion**:
- Among the salts analyzed, KCl is the only salt that does not undergo hydrolysis as it is a neutral salt formed from a strong acid and a strong base.

### Final Answer:
The salt that does not undergo hydrolysis is **KCl**.