Question

The spin only magnetic moment of $[Co{F}_6{]}^{3-}$ is:

Answer 1

The complex $[Co{F}_6{]}^{3-}$ is an octahedral complex.
Here the oxidation state of $Co$ is $+3$
Thus the elctronic configuration of $C{o}^{3+}=\left[Ar\right]3d^6$
So, according to crystal field splitting theory, the electronic configuration in d orbital will be $t_{2g}^4{e}_g^2$
So number of unpaired electrons is = 4
Again spin only magnetic moment is given by, $\sqrt{n(n+2)}$,
Where n =number of unpaired electron
So, the spin only magnetic moment of $[Co{F}_6{]}^{3+}=\sqrt{4(4+2)}=4.89$