Which of the following pairs of species has identical value of bond order?

Solution:

Valence electrons of ${\mathrm{N}}_2=10$ Electronic Configuration $\left(\sigma 2\mathrm{s}{)}^2\right(\sigma \ast 2\mathrm{s}{)}^2{\left(\pi 2{\mathrm{p}}_x\right)}^2{\left(\pi 2{\mathrm{p}}_y\right)}^2{\left(\sigma 2{\mathrm{p}}_z\right)}^2$

Bond order $=(8-2)/2=3$

Valence electrons of ${\mathrm{NO}}^{+}=10 \left(\sigma 2\mathrm{s}{)}^2\right(\sigma \ast 2\mathrm{s}{)}^2{\left(\pi 2{\mathrm{p}}_x\right)}^2{\left(\pi 2{\mathrm{p}}_y\right)}^2{\left(\sigma 2{\mathrm{p}}_z\right)}^2$

Bond order $=(8-2)/2=3$

Valence electrons of $\mathrm{CO}=10$; Same as ${\mathrm{NO}}^{+}$

Valence electrons of ${\mathrm{CN}}^{-}=10;$ Same as ${\mathrm{NO}}^{+}$

Valence electrons of ${\mathrm{N}}_2^{-}=11$ Bond order $=(9-2)/2=3.5$

Valence electrons of ${\mathrm{O}}_2^{+}=11$Electronic configuration $\left(\sigma 2\mathrm{s}{)}^2\right(\sigma \ast 2\mathrm{s}{)}^2{\left(\sigma 2{\mathrm{p}}_z\right)}^2{\left(\pi 2{\mathrm{p}}_x\right)}^2{\left(\pi 2{\mathrm{p}}_y\right)}^2{\left(\pi \ast 2{\mathrm{p}}_x\right)}^1$

Bond order $=(8-3)/2=2.5$