Question

The complex showing a spin-only magnetic moment of $2.82B.M$. is:

• A. $Ni(CO{)}_4$
• B. $[NiC{l}_4{]}^{2-}$
• C. $Ni(PP{h}_3{)}_4$
• D. $\left[Ni\right(CN{)}_4{]}^{2-}$

Answer 1

Answer: (B)

$[NiC{l}_4{]}^{2-}$

$[NiC{l}_4{]}^{2-},O.S$. of $Ni=+2$

$Ni\left(28\right)=\left[Ar\right]3d^{8}4s^2$

$N{i}^{2+}=\left[Ar\right]3d^8$

Now,

Magnetic moment $\mu =\sqrt{n(n+2)}$

$\Rightarrow n=$ Number of unpaired electrons $=2$

Therefore $\mu =\sqrt{2(2+2)}$

$=2.82BM$

Hence, option B is correct.