question_answer

In\[{{[NiC{{l}_{4}}]}^{2-}},\]the number of unpaired electrons, are:

A)  4       

B)  2    

C)  3      

D)  5

Correct Answer: B

Solution :

 In\[{{[NiC{{l}_{4}}]}^{2-}}\]the oxidation number of\[Ni\]is\[+2\]. Electronic configuration of\[Ni\] (Atomic no. =28) \[Ni=[Ar]\,3{{d}^{8}}4{{s}^{2}}\] \[N{{i}^{2+}}=[Ar]\,3{{d}^{8}}\] Or \[[Ar]\]   It is evident that in\[{{[NiC{{l}_{4}}]}^{2-}}\]the number of unpaired electrons are two.