Which of the following can form more than one acidic salt ?

Options

A. `CH_(3)COOH`
B. `H_(3)PO_(4)`
C. `CH_(3)CH_(2)COOH`
D. `ZnO`

Explanation

To determine which of the following can form more than one acidic salt, we need to identify polybasic acids among the options provided. A polybasic acid is one that contains more than one ionizable hydrogen atom, allowing it to form multiple acidic salts upon neutralization with a base.

### Step-by-Step Solution:

1. **Identify Polybasic Acids**:
- A polybasic acid has more than one ionizable hydrogen atom. This means it can donate more than one proton (H⁺) in a reaction.

2. **Examine the Given Options**:
- Let's analyze the options:
- **Option 1**: CH₃CH₂COOH (Propanoic acid) - This is a monobasic acid as it has only one ionizable hydrogen.
- **Option 2**: H₃PO₄ (Phosphoric acid) - This is a polybasic acid as it has three ionizable hydrogens.
- **Option 3**: CH₃CH₂COOH (same as option 1) - Again, this is a monobasic acid.
- **Option 4**: ZnO (Zinc oxide) - This is an amphoteric oxide and does not have ionizable hydrogens.

3. **Determine the Formation of Acidic Salts**:
- **For H₃PO₄**: When neutralized with a base like NaOH, it can form:
- NaH₂PO₄ (sodium dihydrogen phosphate) - one acidic salt
- Na₂HPO₄ (sodium hydrogen phosphate) - another acidic salt
- Since H₃PO₄ can form more than one acidic salt, it qualifies as the correct answer.

4. **Conclusion**:
- The only option that can form more than one acidic salt is **Option 2: H₃PO₄**.

### Final Answer:
**Option 2: H₃PO₄ (Phosphoric acid)** can form more than one acidic salt.

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