Question

The difference in the number of unpaired electrons in ${\mathrm{NiCl}}_2$ and $[\mathrm{Ni}{\left(\mathrm{CN}\right)}_6{]}^{2-}$ is:

• A. 0
• B. 1
• C. 2
• D. 3

Answer 1

The correct option is C

2

Explanation of the correct option:

The correct answer is option C:

The oxidation state of $\mathrm{Ni}$ in ${\mathrm{NiCl}}_2$ is +2.

Thus, its electronic configuration is 3d⁸.

So, the number of unpaired electrons in ${\mathrm{NiCl}}_2$ is 2.

The oxidation state of $\mathrm{Ni}$ in $[\mathrm{Ni}{\left(\mathrm{CN}\right)}_6{]}^{2-}$ is +4.

$\mathrm{CN}$ is a strong field ligand.

Thus, its electronic configuration is 3d⁶.

So, the number of unpaired electrons in $[\mathrm{Ni}{\left(\mathrm{CN}\right)}_6{]}^{2-}$ is 0.
Now, the difference in the number of unpaired electrons in ${\mathrm{NiCl}}_2$ and $[\mathrm{Ni}{\left(\mathrm{CN}\right)}_6{]}^{2-}$ is 2.

Hence, option C is correct, i.e.., 2.