The following mechanism has been proposed for the reaction of $NO$ with $Br_2$ to form $NOBr$ : <br> $NO(g) + Br_2 (g) \rightleftharpoons NOBr_2 (g) $ <br> $NOBr_2 (g) + NO (g) \to 2NOBr (g) $ <br> If the second step is the rate determining step, the order of the reaction with respect to $NO (g)$ is :
