Which of the following statements is incorrect?

• A

  \(\left[\mathrm{VF}_6\right]^{3-}\) is paramagnetic with 2 unpaired electrons.
• B

  \(\left[\mathrm{CuCl}_4\right]^{2-}\) is paramagnetic with 1 unpaired electron.
• C

  \(\left[\mathrm{Co}\left(\mathrm{NH}_3\right)_6\right]^{3+}\) is diamagnetic.
• Correct answer
  D

  \(\left[\mathrm{CoF}_6\right]^{3-}\) is paramagnetic with 2 unpaired electrons.

Solution

Hint : \(\left[\stackrel{\text{III}}{\mathrm{Co}}\mathrm{F}_6\right]^{3-} \mathrm{As} \mathrm{F}^{-}\)is weak field ligand. Oxidation Number of \(\mathrm{Co}=+3\) \(\mathrm{Co}^{3+}\left(4 \mathrm{~s}^0 3 \mathrm{~d}^6\right)\)
Number of unpaired \(\mathrm{e}^{-}=4\)

Hence, the correct answer is option: 'D'.