Among the following compounds, the most acidic is :

Step-by-step solution

The acidity of benzoic acid derivatives is determined by the electronic effects of the substituents present on the benzene ring. The nitro group ( -NO₂ ) is a strong electron-withdrawing group (EWG) due to both its negative inductive effect ( -I ) and negative resonance effect ( -M ). The methoxy group ( -OCH₃ ) is an electron-donating group (EDG) due to its positive resonance effect ( +M ), which outweighs its negative inductive effect ( -I ) at the para position. Comparing the given compounds: 1. 4-methoxybenzoic