Identify the order of reaction for ${\mathrm{NO}}_2+\mathrm{CO}\to \mathrm{NO}+{\mathrm{CO}}_2$

Considered the reaction  ${\mathrm{NO}}_2+\mathrm{CO}\to \mathrm{NO}+{\mathrm{CO}}_2$

If the reaction follows a one elementary step mechanism, the rate law would be

$\mathrm{Rate}=\mathrm{K}\left[{\mathrm{NO}}_2\right]\left[\mathrm{CO}\right]$

However the experimentally determined rate law is, $\mathrm{Rate}=\mathrm{K}{\left[{\mathrm{NO}}_2\right]}^2$

So, order of the reaction is 2.