The acidity of carboxylic acid depends on the electron withdrawing groups attached to carbon atoms. At the same time, the distance between the electron withdrawing groups from carboxylic acid is also responsible for the acidic strength of carboxylic acids. As the distance of electron withdrawing group from carboxylic acid increases, the strength of carboxylic acid decreases. So,
Cl−CH2−CH2−COOH<Cl−CH2−COOH
The electron withdrawing groups increases the acidic strength of carboxylic acids.