The acidic character of alcohols is due the polar nature of O-H bond. An e releasing group `(- CH_(3) -C_(2)H_(5))` increases e density on oxygen thus decreasing the acidity while e withdrawing group increases the acidity.
Which is the strongest acid among:

Options

A. `CH_(3)OH`
B. `CH_(3)CH_(2)OH`
C. `CICH_(2)OH`
D. `NO_(2) - CH_(2)- OH`

Answer

To determine the strongest acid among the given alcohols, we need to analyze the effect of different substituents on the acidity of the alcohols. The acidic character of alcohols is primarily due to the polar nature of the O-H bond, and the presence of electron-releasing or electron-withdrawing groups can significantly affect this acidity.

### Step-by-Step Solution:

1. **Identify the Alcohols**: The alcohols provided are:
- \( \text{CH}_3\text{OH} \) (Methanol)
- \( \text{CH}_3\text{CH}_2\text{OH} \) (Ethanol)
- \( \text{ClCH}_2\text{OH} \) (Chloroethanol)
- \( \text{NO}_2\text{CH}_2\text{OH} \) (Nitroethanol)

2. **Understand the Role of Substituents**:
- **Electron-Releasing Groups** (like \( \text{CH}_3 \) and \( \text{C}_2\text{H}_5 \)): These groups increase the electron density on the oxygen atom of the hydroxyl group, making it less likely to donate a proton (H⁺). This decreases acidity.
- **Electron-Withdrawing Groups** (like \( \text{Cl} \) and \( \text{NO}_2 \)): These groups decrease the electron density on the oxygen atom, making it easier for the alcohol to donate a proton. This increases acidity.

3. **Analyze Each Alcohol**:
- **Methanol (\( \text{CH}_3\text{OH} \))**: Has an electron-releasing group (\( \text{CH}_3 \)), so it has lower acidity.
- **Ethanol (\( \text{CH}_3\text{CH}_2\text{OH} \))**: Also has an electron-releasing group (\( \text{C}_2\text{H}_5 \)), leading to lower acidity.
- **Chloroethanol (\( \text{ClCH}_2\text{OH} \))**: The chlorine atom is an electron-withdrawing group, which increases acidity compared to methanol and ethanol.
- **Nitroethanol (\( \text{NO}_2\text{CH}_2\text{OH} \))**: The nitro group is a strong electron-withdrawing group, significantly increasing the acidity compared to the others.

4. **Compare Acidity**:
- The presence of the nitro group in nitroethanol makes it the strongest acid among the four alcohols because it effectively stabilizes the negative charge on the oxygen after the proton is lost, due to its strong electron-withdrawing nature.

5. **Conclusion**: The strongest acid among the given alcohols is \( \text{NO}_2\text{CH}_2\text{OH} \) (Nitroethanol).

### Final Answer:
The strongest acid among the given alcohols is \( \text{NO}_2\text{CH}_2\text{OH} \).

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