Which among the following is most acidic?

Options

A. `CH_(3)COOH`
B. `ClCH_(2)COOH`
C. `Cl_(2)HC COOH`
D. `C Cl_(3)COOH`

Answer

To determine which among the given compounds is the most acidic, we need to analyze the stability of the anions formed after the loss of a proton (H⁺). The more stable the anion, the more acidic the compound is.

### Step-by-Step Solution

1. **Identify the Compounds**: We have four compounds to analyze:
- Compound 1: CH₃C(=O)OH
- Compound 2: ClCH₂C(=O)OH
- Compound 3: Cl₂CHC(=O)OH
- Compound 4: Cl₃C(=O)OH

2. **Determine the Anions Formed**: When each compound loses H⁺, the following anions are formed:
- From Compound 1: CH₃C(=O)O⁻
- From Compound 2: ClCH₂C(=O)O⁻
- From Compound 3: Cl₂CHC(=O)O⁻
- From Compound 4: Cl₃C(=O)O⁻

3. **Analyze the Stability of the Anions**: The stability of the anions is influenced by the presence of electronegative atoms (like Cl) that can stabilize the negative charge through inductive effects and resonance.
- **Compound 1**: The anion has no electronegative atoms to stabilize the negative charge.
- **Compound 2**: The presence of one Cl atom can stabilize the negative charge through inductive effect.
- **Compound 3**: Two Cl atoms provide greater stabilization than Compound 2.
- **Compound 4**: Three Cl atoms provide the most stabilization due to their strong electronegative nature pulling electron density away from the negative charge.

4. **Conclusion**: Since the stability of the anion increases with the number of electronegative Cl atoms, Compound 4 (Cl₃C(=O)O⁻) is the most stable anion. Therefore, Compound 4 is the most acidic among the given options.

### Final Answer
**Compound 4 (Cl₃C(=O)OH) is the most acidic.**