Chemistry - GOC Question with Solution | TestHub

All four are hydroxybiphenyls. In (II) the para cyano group on the second ring withdraws by resonance through the extended π system and stabilises the phenoxide most; in (III) the meta cyano group can withdraw only by induction, so it helps less. (IV) and (I) carry no cyano group, but in (IV) the $\mathrm{OH}$ is para to the second ring and the phenoxide charge can delocalise into it, while in (I) the $\mathrm{OH}$ is meta and cannot. Hence II $>$ III $>$ IV $>$ I.