Molecularity of the following reaction is $2{\mathrm{NO}}_2+{\mathrm{F}}_2\to 2{\mathrm{NO}}_2\mathrm{F}$

The overall reaction is

$2{\mathrm{NO}}_2+{\mathrm{F}}_2\to 2{\mathrm{NO}}_2\mathrm{F}$

The proposed mechanism is

${\mathrm{NO}}_2+{\mathrm{F}}_2\to {\mathrm{NO}}_2\mathrm{F}+\left[\mathrm{F}\right]; \mathrm{slow} \mathrm{step}$

${\mathrm{NO}}_2+\left[\mathrm{F}\right]\to {\mathrm{NO}}_2\mathrm{F}; \mathrm{fast} \mathrm{step}$

We know that the rate of reaction is determined from slow step.

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

Hence, the given reaction is bimolecular.