Step1 In SO2; sulphur atom is attached to two electron withdrawing oxygen atoms through double bonds. In SO3 ; sulphur atom is attached to 3 electron withdrawing oxygen atoms through double bonds ; thus making sulphur atom in SO3 more electron deficient as compared to SO2. Hence SO3 is more acidic. Solution Step1 In SO2; sulphur atom is attached to two electron withdrawing oxygen atoms through double bonds. In SO3 ; sulphur atom is attached to 3 electron withdrawing oxygen atoms through double bonds ; thus making sulphur atom in SO3 more electron deficient as compared to SO2. Hence SO3 is more acidic..