Question

The diamagnetic species is :

• A. [Ni(CN)$_4$]$^{2-}$
• B. [NiCl$_4$]$^{2-}$
• C. [Fe(CN)$_6$]$^{3-}$
• D. [CoF$_6$]$^{3-}$

Hint:

For a species to be diamagnetic, all electrons must be paired. This results in the absence of a net magnetic moment.

Answer 1

The Correct Option is A

Diamagnetic species are those which have all their electrons paired.
In [Ni(CN)$_4$]$^{2-}$, nickel is in the +2 oxidation state with a fully paired electron configuration, making it diamagnetic.
The other complexes, such as [NiCl$_4$]$^{2-}$, [Fe(CN)$_6$]$^{3-}$, and [CoF$_6$]$^{3-}$, have unpaired electrons and are thus paramagnetic.