Name the gas that can readily decolourise acidified KMnO4 solution.
- SO2
- NO2
- P2O5
- CO2
Answer
(1) SO2
Solution
As per NCERT, moist sulphur dioxide behaves as a reducing agent and decolourises acidified potassium permanganate(VII) solution; this is a convenient test for the gas.
5SO2 + 2MnO4- + 2H2O 5SO42- + 4H+ + 2Mn2+
CO2 and P2O5 are not reducing, and NO2 is mainly an oxidising agent.
Answer: (1)