Chemical Kinetics

For the reaction,

\(\mathrm{H}_{2(g)}+\mathrm{Br}_{2(8)} \longrightarrow 2 \mathrm{HBr}_{(\mathrm{g})}, \mathrm{r}=\mathrm{k}\left[\mathrm{H}_2\right]\left[\mathrm{Br}_2\right]^{\frac{1}{2}}\)

What is the molecularity and order of reaction respectively?