2022 · Q8
Which one of the following is not an example of an oxidation reaction?
General KnowledgeChemistry
- AThe taste of butter changes if left for a longer period
- BA white substance is formed when an aqueous solution of barium chloride is mixed with sodium sulphate solution
- CA reddish-brown powder gets coated on articles made of iron
- DWine gets sour with time
Explanation
Rancid butter (oxidation of fats), rusting of iron (formation of hydrated iron(III) oxide) and souring of wine (oxidation of ethanol to acetic acid) all involve oxidation. The reaction BaCl₂ + Na₂SO₄ → BaSO₄↓ + 2NaCl is a double-displacement precipitation with no change in oxidation numbers — so it is not an oxidation reaction.