Among 2-chloropropanoic acid, 3-chloro-propanoic acid, 2-2-dichloroacetic acid and propanoic acid the K_ a values will be in the order,

Step-by-step solution

Acidic strength k_ a values Due to - I-effect of electron withdrawing - Cl group, chloropropanoic acid is stronger acid than propanoic acid. Further, greater the number of electron withdrawing substitutents, greater would be the acidic strength. Inductive effect decreases rapidly with distance and so, is the acidic strength. Hence, the correct order of acidic strength (or k_ a values) will be