Statement I: The acidic strength of monosubstituted nitrophenol is higher than phenol because of the electron withdrawing nitro group. Statement II: o-nitrophenol, m-nitrophenol and p-nitrophenol will have the same acidic strength as they have one nitro group attached to the phenolic ring. Choose the most appropriate answer from the options given below:

Solution & Explanation

\textbf{Answer:} (C) Statement I is correct but Statement II is incorrect. \textbf{Solution:} Statement I is correct: the electron-withdrawing $-\mathrm{NO}{}_2$ group stabilises the phenoxide ion (by $-I$ and $-R$ effects), so nitrophenols are stronger acids than phenol. Statement II is incorrect: the three isomers do NOT have the same acidic strength. The $-R$ resonance withdrawal operates strongly from the ortho and para positions but not from the meta position. Hence the order of acidity is p-nitrophenol $>$ o-nitrophenol $>$ m-nitrophenol (ortho is slightly lowered by intramolecular H-bonding).