Arrange the following in the increasing order of acidic strength :
(i) `ClCH_2 COOH `
(ii) `CH_2 ClCH_2 COOH`
(iii ) `FCH_2 COOH`
(iv) `CH_3 COOH`

Explanation

To arrange the given compounds in increasing order of acidic strength, we need to analyze the effect of the substituents on the carboxylic acid group (-COOH) in each compound. The acidic strength of a carboxylic acid is influenced by the stability of the carboxylate ion (RCOO⁻) formed after the release of a proton (H⁺). Electron-withdrawing groups (EWGs) stabilize the negative charge on the carboxylate ion, thereby increasing acidity, while electron-donating groups (EDGs) destabilize it, decreasing acidity.

Let's analyze each compound:

1. **ClCH₂COOH**: This compound has a chlorine atom directly attached to the carbon adjacent to the carboxylic acid. Chlorine is an electron-withdrawing group due to its electronegativity, which helps stabilize the carboxylate ion formed after deprotonation.

2. **CH₂ClCH₂COOH**: In this compound, the chlorine atom is further away from the carboxylic acid group (two carbons away). While chlorine still exerts an electron-withdrawing effect, its influence is weaker compared to when it is directly attached to the carbon adjacent to the carboxylic acid. Therefore, this compound will be less acidic than ClCH₂COOH.

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