The number of paramagnetic species from the following is Ni ( CN ) 4 2 - , Ni ( CO ) 4 , NiCl 4 2 - Fe ( CN…

${\left[\mathrm{Ni}(\mathrm{CN}{)}_4\right]}^{2-}:{\mathrm{Ni}}^{+2}=$

It is diamagnetic as  ${}^{-}\mathrm{CN}$ is a strong field ligand and forces electron pairing.

$\left[\mathrm{Ni}(\mathrm{CO}{)}_4\right]:\mathrm{Ni}=$

It is diamagnetic as carbonyl group is a strong field ligand and forces electron pairing.

${\left[{\mathrm{NiCl}}_4\right]}^{2-}:{\mathrm{Ni}}^{2+}=$ 

It is paramagnetic as chloride group is a weak field ligand.

${\left[\mathrm{Fe}(\mathrm{CN}{)}_6\right]}^{4-}:{\mathrm{Fe}}^{2+} :$- 

It is diamagnetic as $–\mathrm{CN}$ is a  strong field ligand which causes pairing of electrons.

${\left[\mathrm{Cu}{\left({\mathrm{NH}}_3\right)}_4\right]}^{+2}:{\mathrm{Cu}}^{+2}\Rightarrow$ Here Copper ion has one unpaired electron, thus it is paramagnetic as it is $3{\mathrm{d}}^9$ configuration.

${\left[\mathrm{Fe}(\mathrm{CN}{)}_6\right]}^{3-} : {\mathrm{Fe}}^{+3}:$ 

It is paramagnetic, here ${\mathrm{CN}}^{-}$ is a strong field ligand

${\left[\mathrm{Fe}{\left({\mathrm{H}}_2\mathrm{O}\right)}_6\right]}^{2+}:{\mathrm{Fe}}^{2+}:$

It is paramagnetic, here ${\mathrm{H}}_2\mathrm{O}$ , here a weak field ligand