The primary valency of Iron in ${\mathrm{K}}_4\left[\mathrm{Fe}(\mathrm{CN}{)}_6\right]$ is satisfied by

Given:- It is given to find how many $C{N}^{-}$ ions satisfy the primary valency of Iron in ${\mathrm{K}}_4\left[\mathrm{Fe}(\mathrm{CN}{)}_6\right]$.

Explanation:-

Iron's primary valency in  $K_{4}Fe(CN{)}_6$ is 2. This complex contains  $F{e}^{2+}$  in the area of coordination.

Thus, the primary valency of Iron in ${\mathrm{K}}_4\left[\mathrm{Fe}(\mathrm{CN}{)}_6\right]$is fulfilled by 2 ${\mathrm{CN}}^{-}ions$.

Hence, (B) is the right response. $Two {\mathrm{CN}}^{-}ions$.