The correct order of acidity for the following is

Options

A. `HCN gt ClCH_(2)COOH gt HCOOH gt CH_(3)COOH`
B. `HCN gt HCOOH gt ClCH_(2)COOH gt CH_(3)COOH`
C. `ClCH_(2)COOH gt HCOOH gt CH_(3)COOH gt HCN`
D. `ClCH_(2)COOH gt HCN gt HCOOH gt CH_(3)COOH`

Explanation

To determine the correct order of acidity for the given compounds, we will analyze the structure and the electron-withdrawing or electron-donating effects of substituents on the carboxylic acids. The compounds to be compared are:

1. CH2ClCOOH (Chloroacetic acid)
2. CH3COOH (Acetic acid)
3. HCN (Hydrogen cyanide)
4. CH3C(=O)OH (Acetic acid)

### Step-by-Step Solution:

1. **Identify the Compounds**:
We have the following compounds:
- CH2ClCOOH: Chloroacetic acid
- CH3COOH: Acetic acid
- HCN: Hydrogen cyanide
- CH3C(=O)OH: Acetic acid (this seems to be a repetition)

2. **Analyze the Effects of Substituents**:
- **CH2ClCOOH**: The chlorine atom is highly electronegative and exerts a strong electron-withdrawing effect through the inductive effect. This increases the acidity as it stabilizes the negative charge on the conjugate base (CH2ClCOO^-).
- **CH3COOH**: The methyl group (CH3) is an electron-donating group, which decreases the acidity compared to chloroacetic acid because it destabilizes the negative charge on the conjugate base (CH3COO^-).
- **HCN**: Hydrogen cyanide is a weak acid. The cyanide group (CN) is less effective at stabilizing the negative charge compared to the carboxylate ions formed from carboxylic acids.
- **CH3C(=O)OH**: This is another representation of acetic acid, which has the same properties as CH3COOH.

3. **Compare the Acidity**:
- The most acidic compound will be CH2ClCOOH due to the strong electron-withdrawing effect of chlorine.
- The next in acidity will be CH3COOH (or CH3C(=O)OH), as it is a weaker acid than chloroacetic acid but stronger than HCN.
- HCN is the least acidic among these compounds.

4. **Order of Acidity**:
Based on the analysis, the order of acidity from strongest to weakest is:
- CH2ClCOOH > CH3COOH = CH3C(=O)OH > HCN

### Final Answer:
The correct order of acidity for the given compounds is:
**CH2ClCOOH > CH3COOH = CH3C(=O)OH > HCN**