Which salt is an acid salt ?

Options

A. `Na_2SO_4`
B. `BiOCl`
C. `Pb(OH)Cl`
D. `Na_2HPO_4`

Answer

To determine which salt is an acid salt among the given options, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Definition of Acid Salts**:
Acid salts are formed from the partial neutralization of a diprotic or polyprotic acid. They can be classified as:
- A salt formed from a strong acid and a weak base.
- A salt formed from a weak acid and a strong base.
- A salt formed from a weak acid and a weak base.

2. **Identify the Given Options**:
We have four options (A, B, C, D) to evaluate. For this solution, we will focus on option D, which is Na2HPO4.

3. **Analyze Na2HPO4**:
- Na2HPO4 is the disodium salt of phosphoric acid (H3PO4).
- It is formed from the partial neutralization of phosphoric acid (a weak acid) with sodium hydroxide (a strong base).
- In solution, Na2HPO4 can release H+ ions, which is characteristic of acid salts.

4. **Conclusion**:
Since Na2HPO4 can furnish H+ ions in solution and is formed from a weak acid (H3PO4) and a strong base (NaOH), it qualifies as an acid salt.

5. **Final Answer**:
Therefore, the correct answer is option D: Na2HPO4.