What is the bond order of carbon monoxide? 

$\left(\sigma 1s^2{\sigma }^{\ast }1s^2\sigma 2s^2{\sigma }^{\ast }2s^2\pi 2p_x^2\equiv \pi 2p_y^2\sigma 2p_z^2\right)$

$\text{ Bond order }=\frac{1}{2}\left({\mathrm{N}}_b-{\mathrm{N}}_a\right)=\frac{1}{2}(10-4)=3.0$