Oxidation number of the central Iron atom in the complex ${\mathrm{Fe}}_4{\left[\mathrm{Fe}(\mathrm{CN}{)}_6\right]}_3$ is.

The oxidation number of an atom is the charge that atom would have if the compound was composed of ions. oxidation number of the central iron atom in the complex ${\mathrm{Fe}}_4{\left[\mathrm{Fe}(\mathrm{CN}{)}_6\right]}_3$ is 2.

Let the oxidation number of Fe be x.
Oxidation number of $\mathrm{CN}=-1,\mathrm{K}=+1$

In ${\mathrm{K}}_4\left[\mathrm{Fe}(\mathrm{CN}{)}_6\right]:4\times 1+\mathrm{x}+6\times (-1)=0$

Hence correct answer is 2.