The pH of which salt is independent of its concentration ?

Options

A. `(CH_(3)COO)C_(5)H_(5)N`
B. `NaH_(2)PO_(4)`
C. `Na_(2)HPO_(4)`
D. `NH_(4)CN`

Explanation

To determine the salt whose pH is independent of its concentration, we need to analyze the properties of different types of salts.

### Step-by-Step Solution:

1. **Understand the Types of Salts**:
- Salts can be formed from strong acids and strong bases, weak acids and strong bases, strong acids and weak bases, or weak acids and weak bases.
- Salts derived from weak acids and weak bases are of particular interest here.

2. **Identify Amphiprotic Salts**:
- Amphiprotic salts can act as either an acid or a base. Their pH is not dependent on concentration because they can donate or accept protons depending on the environment.
- The pH of amphiprotic salts can be calculated using the formula:
\[ \text{pH} = \frac{\text{pKa}_1 + \text{pKa}_2}{2} \]

3. **Consider Weak Acid and Weak Base Salts**:
- The pH of salts formed from weak acids and weak bases is also independent of concentration. The formula for calculating their pH is:
\[ \text{pH} = \frac{1}{2} \text{pK}_w + \text{pKa} - \text{pKb} \]
- Here, \( \text{pK}_w \) is the ion product of water.

4. **Evaluate the Options**:
- If the question provides options, you would need to identify which salts are amphiprotic or formed from weak acids and weak bases.
- All such salts will have a pH that does not change with concentration.

5. **Conclusion**:
- The salts whose pH is independent of concentration are those that are either amphiprotic or formed from weak acids and weak bases.

### Final Answer:
The pH of amphiprotic salts and salts formed from weak acids and weak bases is independent of their concentration.