Which among the following acids form one normal salt and one acidic salt?

Options

A. Acetic acid
B. Phosphorous acid
C. Phosphoric acid
D. Both (b) and (c)

Explanation

To solve the question "Which among the following acids form one normal salt and one acidic salt?", we need to analyze the given acids and their ability to form normal and acidic salts.

### Step-by-Step Solution:

1. **Understanding Normal and Acidic Salts**:
- A **normal salt** is formed when all replaceable hydrogen ions (H⁺) in an acid are replaced by metal ions.
- An **acidic salt** is formed when only some of the replaceable hydrogen ions are replaced by metal ions.

2. **Identifying the Acids**:
- We need to consider the acids mentioned in the question. The video transcript discusses two acids: **phosphorus acid (H₃PO₃)** and **phosphoric acid (H₃PO₄)**.

3. **Analyzing Phosphorus Acid (H₃PO₃)**:
- Phosphorus acid has 2 replaceable hydrogen ions.
- When one hydrogen is replaced, we get **NaH₂PO₃** (acidic salt).
- When both hydrogens are replaced, we get **Na₂HPO₃** (normal salt).
- The third hydrogen is not replaceable, confirming that we can form one normal salt and one acidic salt.

4. **Analyzing Phosphoric Acid (H₃PO₄)**:
- Phosphoric acid has 3 replaceable hydrogen ions.
- When one hydrogen is replaced, we get **NaH₂PO₄** (acidic salt).
- When two hydrogens are replaced, we get **Na₂HPO₄** (also an acidic salt).
- When all three hydrogens are replaced, we get **Na₃PO₄** (normal salt).
- Here, we can form two acidic salts and one normal salt.

5. **Conclusion**:
- From the analysis, we see that **phosphorus acid (H₃PO₃)** is the only acid that forms one normal salt and one acidic salt.
- Therefore, the answer to the question is **phosphorus acid (H₃PO₃)**.