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Question: Answered & Verified by Expert
The number of unpaired electrons in the complex ion $\left[\mathrm{CoF}_6\right]^{3-}$ is:
(Atomic no. : $\mathrm{Co}=27$ )
ChemistryCoordination CompoundsNEETNEET 2003
Options:
  • A 2
  • B 3
  • C 4
  • D Zero
Solution:
2516 Upvotes Verified Answer
The correct answer is: 4
\(\mathrm{Co}(\mathrm{Z}=27)\) has observed electronic configuration \([\mathrm{Ar}] 3 \mathrm{~d}^7 4 \mathrm{~s}^2 . \mathrm{Co}^{3+}\) has electronic configuration \([\mathrm{Ar}] 3 \mathrm{~d}^6 4 \mathrm{~s}^0 \cdot\left[\mathrm{CoF}_6\right]^{3-}\) is a high spin complex and contains 4 unpaired electrons.

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