Identify the correct order in the following :

For ${\mathrm{NO}}_2^{-}$​, Band order $=\frac{6-3}{2}=1.5$

For ${\mathrm{NO}}_3^{-}$, Band order $=\frac{6-4}{2}=1$

The order of Band order is :

${\mathrm{NO}}_3^{-}>{\mathrm{NO}}_2^{-}$

Hence correct option is C.