In potassium ferrocyanide, there are ______ pairs of electrons in...

Potassium ferrocyanide, ${K}_{4}\left[Fe{\left(CN\right)}_{6}\right]$, has a central iron ion that is coordinated with six cyanide ligands in an octahedral geometry. The oxidation state of the iron ion in potassium ferrocyanide is $+ 2$, hence has ${d}^{2}{sp}^{3}$ hybridised state. On applying $C . F . T$. it shows that all the $6$ electrons of $d$ subshell are present in the form of three pairs in ${t}_{2g}$ orbitals. Hence answer is $3$.