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NEETChemistryd and f Block Elements

A transition metal M belongs to the 3d series and possesses the highest melting point among the elements of this series. What is the spin-only magnetic moment of the M ³⁺ ion?

Options

  1. A4.90 BM
  2. B3.87 BM
  3. C5.92 BM
  4. D6.93 BM

Correct answer

B. 3.87 BM

Step-by-step solution

In the 3d transition series, the melting point generally increases with the number of unpaired electrons, reaching a maximum at chromium ( Cr ), which has a 3d⁵ 4s¹ configuration. (Manganese shows an anomalous dip and does not have the highest melting point). Thus, the metal M is Chromium ( Cr ). The electronic configuration of Cr is [ Ar ] 3d⁵ 4s¹ . The electronic configuration of the Cr ³⁺ ion is [ Ar ] 3d³ . Number of unpaired electrons ( n ) = 3 . The spin-only magnetic moment ( ) is given by n(n+2) BM . = 3(3+

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