List of top Chemistry Questions on Order of Reaction asked in BITSAT

For the reaction $H _{2}( g )+ Br _{2}( g ) \rightarrow 2 HBr ( g )$, the experiment data suggested that $r = k \left[ H _{2}\right]\left[ Br _{2}\right]^{1 / 2} .$ The molecularity and order of the reaction are respectively: