Question

P- nitrophenol is more acidic than p-methyl phenol . why?

Answer 1

The mesomeric effect (or resonance effect) is the movement of π electrons toward or away from a functional group. Now +M effect increases electron density on ring and -M effect decreases electron density in the ring or in other words it deactivates the ring. P - nitrophenol contains -NO2 group that shows -M effect and also -I effect and as Lewis acid is one that accepts electron, any electron deficienct ring will be more acidic than electron rich ring. P-methylphenol contains -CH3 group that shows +M effect via hyperconjugation and thus increases stability of ring and shows electron delocalisation, also +I effect, thus increases electron density on ring and thus makes it more basic since bases tends to lose electron.