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 salts provided in the options. Hydrolysis occurs when a salt reacts with water to produce an acidic or basic solution. Typically, salts formed from weak acids or weak bases will undergo hydrolysis, while those formed from strong acids and strong bases will not.

### Step-by-Step Solution:

1. **Identify the salts and their components:**
- **Option 1: KCl**
- KCl is formed from KOH (potassium hydroxide) and HCl (hydrochloric acid).
- **Option 2: NaNO3**
- NaNO3 is formed from NaOH (sodium hydroxide) and HNO3 (nitric acid).
- **Option 3: CaSO4**
- CaSO4 is formed from Ca(OH)2 (calcium hydroxide) and H2SO4 (sulfuric acid).
- **Option 4: HCOONH4**
- HCOONH4 is formed from NH4OH (ammonium hydroxide) and HCOOH (formic acid).

2. **Analyze each salt:**
- **KCl (Option 1):**
- KOH is a strong base, and HCl is a strong acid. Since both components are strong, KCl does not undergo hydrolysis.
- **NaNO3 (Option 2):**
- NaOH is a strong base, and HNO3 is a strong acid. Similar to KCl, NaNO3 does not undergo hydrolysis.
- **CaSO4 (Option 3):**
- Ca(OH)2 is a strong base, and H2SO4 is a strong acid. Therefore, CaSO4 also does not undergo hydrolysis.
- **HCOONH4 (Option 4):**
- NH4OH is a weak base, and HCOOH is a weak acid. Since this salt is formed from a weak base and a weak acid, HCOONH4 will undergo hydrolysis.

3. **Conclusion:**
- The only salt that undergoes hydrolysis is **HCOONH4** (Option 4).

### Final Answer:
The salt that undergoes hydrolysis is **HCOONH4** (Option 4).