Two statements — Statement-I: Heating NaCl with concentrated H₂SO₄ and MnO₂ results in oxidation of Mn. Statement-II: Heating NaI with concentrated H₂SO₄ and MnO₂ results in reduction of Mn. Choose the most appropriate answer:
- A.Both Statement-I and Statement-II are correct
- B.Both Statement-I and Statement-II are incorrect
- C.Statement-I is correct but Statement-II is incorrect
- D.Statement-I is incorrect but Statement-II is correct✓
Correct Answer
(D) Statement-I is incorrect but Statement-II is correct
Solution & Explanation
Key idea: oxidation = loss of electrons (oxidation number rises); reduction = gain of electrons (oxidation number falls). Track Mn only. In both reactions MnO₂ is the oxidising agent. Mn begins as Mn⁴⁺ in MnO₂. With NaCl: 2NaCl + MnO₂ + 2H₂SO₄ → Na₂SO₄ + MnSO₄ + Cl₂ + 2H₂O. Mn goes +4 → +2 in MnSO₄, so Mn is REDUCED. With NaI: 2NaI + MnO₂ + 2H₂SO₄ → Na₂SO₄ + MnSO₄ + I₂ + 2H₂O. Again Mn goes +4 → +2, so Mn is REDUCED. Therefore Statement-I (Mn oxidised with NaCl) is incorrect, and Statement-II (Mn reduced with NaI) is correct. Answer: option D.
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