Which of the following molecular orbital is not used in filling of ${\mathrm{N}}_2^{++}$?

Nitrogen molecule  $\left(N_2\right):$ In its ground state, nitrogen has the electronic structure $1^{\prime \prime }s\left((Z=7),1{\mathrm{s}}^{2}2{\mathrm{s}}^{2}2{\mathrm{p}}_{\mathrm{x}}^{1}2{\mathrm{p}}_{\mathrm{y}}^{1}2{\mathrm{p}}_{\mathrm{z}}^1\right.$. Thus, the nitrogen molecule $\left(N_2\right)$ contains a total of 14 electrons. The different molecular orbitals, in ascending energy sequence, may hold all 14 of these electrons.

${\mathrm{N}}_2:\mathrm{KK}{\left({\sigma }_{2\mathrm{s}}\right)}^2{\left({\sigma }_{2\mathrm{s}}^{\ast }\right)}^2{\left({\pi }_{2{\mathrm{p}}_{\mathrm{x}}}\right)}^2{\left({\pi }_{2\mathrm{py}}\right)}^2{\left({\sigma }_{2\mathrm{px}}^{\ast }\right)}^2{\left({\pi }_{2\mathrm{py}}^{\ast }\right)}^2$

Hence ${\sigma }_{2p_z}$ is not filling of  ${\mathrm{N}}_2^{++}$ 

Hence correct option is B.