Question

benzoic acid is stronger than acetic acid

Answer 1

Benzene is an electron withdrawing group and hence it creates an addition partial positive charge on the Oxygen Atom present in the -OH group through propagation thus increasing its electron withdrawing power.

But no such effect exists in acetic acid. In fact the -CH3 (methyl group) is an electron donating group which reduces the electron withdrawing power of Oxygen Atom.

Hence Benzoic acid is more acidic than Acetic acid.

Answer 2

because the negative charge on benzoic acid is stable due to -I of benzene but the negative charge of acetic acid is destabilised due to the +I effect of CH3
(the negative charge is after removing the hydrogen at COOH group)