Which one of the followinf is acid salt?

Options

A. `Na_(2)S`
B. `Na_(2)SO_(3)`
C. `NaHSO_(3)`
D. `Na_(2)SO_(4)`

Explanation

To determine which of the given salts is an acid salt, we need to understand the definitions and characteristics of different types of salts.

### Step-by-step Solution:

1. **Understand the Types of Salts**:
- **Neutral Salts**: Formed from the reaction of a strong acid with a strong base. Example: HCl + NaOH → NaCl + H2O. The pH of neutral salts is 7.
- **Acidic Salts**: Formed from the reaction of a strong acid with a weak base. Example: HCl + NH4OH → NH4Cl + H2O. The pH of acidic salts is less than 7.
- **Basic Salts**: Formed from the reaction of a weak acid with a strong base. Example: CH3COOH + NaOH → CH3COONa + H2O. The pH of basic salts is greater than 7.

2. **Identify the Given Salts**:
- Na2S
- Na2SO3
- Na2SO4
- NaHSO3

3. **Analyze Each Salt**:
- **Na2S**: Formed from H2S (weak acid) and NaOH (strong base) → Basic salt.
- **Na2SO3**: Formed from H2SO3 (weak acid) and NaOH (strong base) → Basic salt.
- **Na2SO4**: Formed from H2SO4 (strong acid) and NaOH (strong base) → Neutral salt.
- **NaHSO3**: Formed from H2SO3 (weak acid) and NaOH (strong base). This salt has one replaceable H atom, which can donate H⁺ ions, making it an acidic salt.

4. **Conclusion**:
- The only salt that fits the definition of an acidic salt is **NaHSO3**.

### Final Answer:
The correct answer is **NaHSO3**, which is an acid salt.