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

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

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

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

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

Among the given complexes, number of paramagnetic complexes is

Complexes in which central atom has unpaired electrons is said to be paramagnetic in nature and where unpaired electrons are not present are diamagnetic in nature.

${\left[\mathrm{Fe}{\left(\mathrm{CN}\right)}_6\right]}^{3-}$,   ${\mathrm{Fe}}^{+3}$  $\left(3{\mathrm{d}}^5\right) \to {{\mathrm{t}}_{2\mathrm{g}}^{}}^{2,2} {{\mathrm{e}}_{\mathrm{g}}}^1$, paramagnetic (one unpaired electron)

${\left[\mathrm{Fe}{\left(\mathrm{CN}\right)}_6\right]}^{4-}, {\mathrm{Fe}}^{+2} \left(3{\mathrm{d}}^6\right)\to {{\mathrm{t}}_{2\mathrm{g}}}^6{{\mathrm{e}}_{\mathrm{g}}}^0$ ,diamagnetic 

${\left[\mathrm{Ti}{\left(\mathrm{CN}\right)}_6\right]}^{3-}, {\mathrm{Ti}}^{+3}\left(3{\mathrm{d}}^1\right)\to {{\mathrm{t}}_{2\mathrm{g}}}^1$ , Paramagnetic ($1$ unpaired electron)

${\left[\mathrm{Ni}{\left(\mathrm{CN}\right)}_4\right]}^{2-}, {\mathrm{Ni}}^{+2}\left(3d^8\right)\to$ Diamagnetic

${\left[\mathrm{Co}{\left(\mathrm{CN}\right)}_6\right]}^{3-}, {\mathrm{Co}}^{+3}\left(3{\mathrm{d}}^6\right)\to {{\mathrm{t}}_{2\mathrm{g}}}^6, \mathrm{diamagnetic}$