Which salt undergoes hydrolysis?

Options

A. `KCI`
B. `NaNO_(3)`
C. `CaSO_(4)`
D. `HCOONH_(4)`

Explanation

To determine which salt undergoes hydrolysis, we need to analyze the nature of the acids and bases from which the salts are derived. Hydrolysis occurs when a salt is formed from a weak acid or a weak base. Let's evaluate each option step by step.

### Step-by-Step Solution:

1. **Understanding Hydrolysis**:
- Hydrolysis is a reaction of a salt with water, resulting in the formation of an acid and a base. It typically occurs when at least one of the components (acid or base) is weak.

2. **Analyzing the Options**:
- **Option A: KCl**
- KCl is derived from KOH (a strong base) and HCl (a strong acid).
- Since both the acid and base are strong, KCl will not undergo hydrolysis.

- **Option B: NaNO3**
- NaNO3 is derived from NaOH (a strong base) and HNO3 (a strong acid).
- Similar to KCl, both components are strong, so NaNO3 will not undergo hydrolysis.

- **Option C: CaSO4**
- CaSO4 is derived from Ca(OH)2 (a strong base) and H2SO4 (a strong acid).
- Again, both components are strong, indicating that CaSO4 will not undergo hydrolysis.

- **Option D: HCOONH4 (Ammonium formate)**
- HCOONH4 is derived from HCOOH (formic acid, a weak acid) and NH3 (ammonia, a weak base).
- Since both the acid and base are weak, HCOONH4 will undergo hydrolysis.

3. **Conclusion**:
- The only salt that undergoes hydrolysis among the given options is **HCOONH4** (Option D).

### Final Answer:
**HCOONH4 (Option D) undergoes hydrolysis.**

---