Which acid has lowest pK_(a)

1.	Which acid has lowest pK_(a)
Answer» <P>`p-`Methoxybenzoic acid `p-`Chlorobenzoic acid `p-`Aminobenzoic acid `p-`TOLUIC acid Solution :Among the substituents given CHLORO group has stronger electron withdrawing EFFECT and hence is strongest acid with highest `K_(a)` and lowest `pK_(a)` VALUE respectively

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