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COMEDK202510 May 2025Morning ShiftChemistryd and f Block ElementsActual

What is the spin only magnetic moment of the metal ion in P and the oxidation number of Sulphur in the oxidised product Z ?

Options

  1. A=5.00 BM Oxidation number =0
  2. B=1.732 BM Oxidation number =+6
  3. C=0 Oxidation number =+4
  4. D=5.92 BM Oxidation number =+2

Correct answer

B. =1.732 BM Oxidation number =+6

Step-by-step solution

Pyrolusite is MnO₂ . When fused with KOH and KNO₃ , it forms potassium manganate ( K₂MnO₄ ), which is compound P . 2MnO₂ + 4KOH + O₂ 2K₂MnO₄ + 2H₂O . In K₂MnO₄ , the manganese ion is MnO₄²⁻ . The oxidation state of Mn is +6 . The electronic configuration of Mn⁶⁺ is [Ar] 3d^1 . The number of unpaired electrons n = 1 . The spin-only magnetic moment = n(n+2) = 1(1+2) = 3 1.732 BM . Compound P ( K₂MnO₄ ) undergoes disproportionation in acidic medium to form MnO₂ (blackish brown, X ) and KMnO₄ ( Y ). 3MnO₄²⁻ + 4H^+ 2MnO

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