The correct option is C All of the above
Sulphur dioxide may be recognized by its
(A)
Characteristic pungent smell of burning sulphur.
It has characteristic smell of rotten eggs.
(B)
Ability to turn dichromate paper green.
In acidic medium, SO2 reduces potassium dichromate to green coloured chromic sulphate.
(C)
Ability to decolourize acidified KMnO4
solution
In acidic medium, SO2 reduces violet / purple colored potassium permangnate to manganese sulphate.