Alkaline oxidative fusion of MnO₂ gives "A" which on electrolytic oxidation in alkaline solution produces B. A and B respectively are

Solution

Chemistry ma’am · 3 steps

Mn climbs +4 to +6 by fusion, then +6 to +7 by electrolysis: the factory route to KMnO₄.

1. Fusion gives manganate. MnO₂ (Mn is +4) is fused with KOH in air, or with an oxidant such as KNO₃. Mn is oxidised to +6, giving green potassium manganate. So A is MnO₄²⁻.

   2MnO₂ + 4KOH + O₂ → 2K₂MnO₄ + 2H₂O

2. Electrolysis gives permanganate. In alkaline solution, the manganate ion loses one electron at the anode: MnO₄²⁻ → MnO₄⁻ + e⁻. Mn goes from +6 to +7, and the green solution turns purple. So B is MnO₄⁻.
3. So. A is MnO₄²⁻ and B is MnO₄⁻, which is option (c).

The idea to keep. For KMnO₄ preparation, remember green to purple: alkaline fusion takes Mn from +4 to +6 as MnO₄²⁻, and electrolytic oxidation takes it from +6 to +7 as MnO₄⁻.

Answer from the NTA final answer key. Solution by PrepWiser.