A.NO2 does not play any role in photochemical smog
B.SO3 is more harmful air pollutant than SO2✓ Correct
C.SO2 dos not affect larynx (voice box)
D.NO is more toxic to living tissues than NO2
Explanation
Among the following options, option (b) is incorrect as sulphur dioxide is much more harmful pollutant the sulphur trioxide, rest all other options are correct. Hence, the correct answer is option (b)