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NEETChemistryd and f Block Elements

When MnO ₂ is fused with KOH in the presence of an oxidising agent like KNO ₃ , a dark green coloured compound is formed. The calculated 'spin-only' magnetic moment of the transition metal ion in this dark green compound is :

Options

  1. A0.00 BM
  2. B3.87 BM
  3. C1.73 BM
  4. D5.92 BM

Correct answer

C. 1.73 BM

Step-by-step solution

The fusion of MnO ₂ with KOH and an oxidising agent like KNO ₃ produces potassium manganate ( K ₂ MnO ₄ ), which is dark green in colour. The oxidation state of Mn in the manganate ion ( MnO ₄²⁻ ) is +6 . The atomic number of Mn is 25 . Electronic configuration of neutral Mn is [ Ar ] 3d^5 4s^2 . Electronic configuration of Mn ⁶⁺ is [ Ar ] 3d^1 . Number of unpaired electrons, n = 1 . Spin-only magnetic moment, = n(n+2) BM . = 1(1+2) = 3 1.73 BM . Note: Confusing the green manganate with the purple permanganate ( KM

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