Concept:Acidic strength is magnified by the presence of electron-withdrawing groups (EWG), which operate via the Inductive (\( -I \)) effect to disperse the negative charge of the conjugate base.
Solution:- Acetic acid (\( \text{CH}_3\text{COOH} \)) has zero electron-withdrawing halogens.
- Chloroacetic acid (\( \text{CH}_2\text{ClCOOH} \)) has 1 chlorine atom pulling electron density.
- Dichloroacetic acid (\( \text{CHCl}_2\text{COOH} \)) has 2 chlorine atoms, exerting a double \( -I \) pull, making it the strongest.
- The correct decreasing order is therefore: Dichloroacetic > Chloroacetic > Acetic.
Why other options are incorrect:Options A and C incorrectly list acetic acid as the strongest. Option D has typos (\( \text{CH}_2\text{COOH} \) is not a complete molecule) and incorrect ordering.
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