The principle behind the acidity order `Cl_(3)` CCOOH`gt Cl_(2)` CHCOOH `gt "ClCH"_(2)` COOH `gt CH_(3)` COOH is the withdrawal of electron and liberation of protons, it is due to

Options

A. Inductive effect
B. Resonance effect
C. Electromeric effect
D. mesomeric effect

Explanation

To determine the principle behind the acidity order of the compounds `Cl3CCOOH > Cl2CHCOOH > ClCH2COOH > CH3COOH`, we need to analyze the stability of the conjugate bases formed after the release of protons (H+ ions) from these acids. The stability of the conjugate base is influenced by the electron-withdrawing or electron-donating effects of substituents attached to the carbon chain.

### Step-by-Step Solution:

1. **Understanding Acidity**:
- Acids donate protons (H+ ions) and form conjugate bases. The strength of an acid is determined by the stability of its conjugate base (A-).
- More stable conjugate bases correspond to stronger acids.

2. **Identifying the Conjugate Bases**:
- For `Cl3CCOOH`, the conjugate base is `Cl3CCO−`.
- For `Cl2CHCOOH`, the conjugate base is `Cl2CHCO−`.
- For `ClCH2COOH`, the conjugate base is `ClCH2CO−`.
- For `CH3COOH`, the conjugate base is `CH3CO−`.

3. **Analyzing the Effects of Substituents**:
- The presence of chlorine (Cl) atoms in the compounds is significant because chlorine is an electron-withdrawing group (EWG) due to its electronegativity.
- The inductive effect (−I effect) of chlorine stabilizes the negative charge on the conjugate base by pulling electron density away from the negatively charged oxygen.

4. **Comparing the Stability of Conjugate Bases**:
- `Cl3CCO−` has three chlorine atoms, which provide a strong −I effect, making it the most stable conjugate base and thus the strongest acid.
- `Cl2CHCO−` has two chlorine atoms, providing a lesser −I effect than `Cl3CCO−`, making it less stable than the first.
- `ClCH2CO−` has one chlorine atom, resulting in even less stability than `Cl2CHCO−`.
- `CH3CO−` has no chlorine atoms and instead has a methyl group (CH3), which is an electron-donating group (+I effect), making it the least stable conjugate base.

5. **Conclusion**:
- The order of acidity is determined by the number of electron-withdrawing chlorine atoms present. The more chlorine atoms, the greater the −I effect, leading to increased stability of the conjugate base.
- Therefore, the principle behind the acidity order is the inductive effect of the chlorine substituents.

### Final Answer:
The principle behind the acidity order `Cl3CCOOH > Cl2CHCOOH > ClCH2COOH > CH3COOH` is due to the inductive effect (−I effect) of the chlorine atoms, which withdraw electron density and stabilize the conjugate base.