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COMEDK2022ChemistryRedox Reactions

Which of the following gas readily de-colourises the acidified KMnO ₄ solution?

Options

  1. ACO ₂
  2. BSO ₂
  3. CP ₂ O ₅
  4. DNO ₂

Correct answer

B. SO ₂

Step-by-step solution

Acidified potassium permanganate ( KMnO ₄ ) is a strong oxidizing agent. It reacts with reducing agents to get reduced, resulting in the loss of its characteristic purple color. Among the given gases, SO ₂ acts as a strong reducing agent. The reaction is as follows: 5 SO ₂ + 2 KMnO ₄ + 2 H ₂ O K ₂ SO ₄ + 2 MnSO ₄ + 2 H ₂ SO ₄ In this reaction, the oxidation state of sulfur increases from +4 to +6 , and the oxidation state of manganese decreases from +7 to +2 . The formation of colorless Mn ²⁺ ions leads to the de-c

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