The correct order of acidity for the following compounds is:
II < IV < III < I
II < III < I < IV
II < III < IV < I
III < II < I < IV
The correct option is B II < III < I < IV Acidity will be most when the conjugate base is most stabilised.
Carboxylic acid is more acidic than phenol. For nitro substituted phenol, NO2 when present at para position will show maximum acidity due to -R effect while at meta position it shows only -I effect. Since -R effect is more pronounced over -I therefore (I) will be more acidic than (III). Methyl group destabilises the conjugate base through +I effect and hence (II) will be least acidic.