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Question: Answered & Verified by Expert
In $\left[\mathrm{NiCl}_4\right]^{2-}$, the number of unpaired electrons, are
Chemistryd and f Block ElementsJIPMERJIPMER 2005
Options:
  • A 4
  • B 2
  • C 3
  • D 5
Solution:
2927 Upvotes Verified Answer
The correct answer is: 2
$\operatorname{In}\left[\mathrm{NiCl}_4\right]^{2-}$ the oxidation number of Ni is $+2$
Electronic configuration of Ni
$\begin{aligned} &\text { (at no. }=28) \\ & \mathrm{Ni}=[\mathrm{Ar}] 3 d^8 4 s^2 \\ & \mathrm{Ni}^{+2}=[\mathrm{Ar}] 3 d^8\end{aligned}$
or $\quad[\mathrm{Ar}]$
$\begin{array}{|c|c|c|c|c|}
\hline\uparrow \downarrow & \uparrow \downarrow & \uparrow \downarrow & \uparrow & \uparrow \\
\hline
\end{array}$
It is evident that in $\left[\mathrm{NiCl}_4\right]^{2-}$ the number of unpaired electrons are two.

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