Chemistry - GOC Question with Solution | TestHub

Larger the value of $\mathrm{p}{K}_{ar}$ smaller will be its acidity. Out of the four groups, $-\mathrm{COOH},-{\mathrm{NO}}_2$ and $-\mathrm{CN}$ are $e^{-}$withdrawing which makes benzoic acid more acidic whereas $-{\mathrm{OCH}}_3$ is $e^{-}$ donating which reduces the acidity (makes ${\mathrm{H}}^{+}$ less easily available). $\mathrm{p}{K}_a$ value increases if ${\mathrm{OCH}}_3$ is present at para-position of benzoic acid.