SO2 is a colorless and pungent smell gas.
It can be detected by using potassium permanganate solution. When SO2 is passed through an acidified potassium permanganate solution, then it decolonises the soln as it reduces MnO4- ions to Mn2+ ions.
5SO2 + 2MnO- 4, + 2H2O→ 5SO4 2- +4H+ +2Mn2+
