Question

Which gas decolourises potassium permanganate (KMnO₄) solution?

Options

• Sulphur dioxide

• Ammonia

• Hydrogen chloride

• Carbon dioxide

Answer 1

Sulphur dioxide

Explanation:

Sulphur dioxide gas (SO₂) decolourises potassium permanganate (KMnO₄) solution because sulphur dioxide acts as a reducing agent while potassium permanganate functions as an oxidizing agent. Both substances react with and decolorize potassium permanganate. A redox reaction occurs in which sulphur dioxide gas (SO₂) is oxidized.