Question

Assertion $[Co{F}_6{]}^{3-}$ is paramagnetic. Reason $C{o}^{3+}$ has $3d^6$ outer electronic configuration. The unpaired electrons do not pair up because of weak field provided by $F^{-}$ .

• A. Both Assertion and Reason are true and Reason is the correct explanation of assertion.
• B. Both Assertion and Reason are true and Reason is not the correct explanation of Assertion.
• C. Assertion is true but Reason is false.
• D. Both Assertion and Reasonl are false.

Answer 1

Answer: (A)

In complex$[Co{F}_6{]}^{3-}$
Oxidation number of Co= +3
Electronic configuration of
$C{o}^{3+}=1s^2,2s^2,2p^6,3s^{2}3p^6,3d^6$
In $C{o}^{3+}$
In $C{o}^{3+}$ number of unpaired electrons is four, and $F^{-}$ is the ligand of weak field. Hence, it does not paired up electrons of d-orbital.
So, In$[Co{F}_6){]}^{3-}$
So, $[Co{F}_6{]}^{3-}$ is paramagnetic.
$C{o}^{3+}$ has $3d^6$ outer electronic configuration, but four unpaired electrons do not pair up because of weak field provided by $F^{-}.$