Chemistry - GOC Question with Solution | TestHub

Of the four compounds given, the most acidic compound is o−nitrobenzoic acid because its anion is stabilised by the −I and −R effects of NO2 group. Other substituents like Cl and Br also stabilise the anion by −I effect only. The methoxy substituent stabilises the anion by −I effect but destabilises it by the dominating +R effect.