For the reaction N_2+3 H_2 arrow 2 NH_3 , the rate expression is -d...

For the reaction $\mathrm{N}_2+3 \mathrm{H}_2 \rightarrow 2 \mathrm{NH}_3$, the rate expression is $-\mathrm{d}$\left[\mathrm{NH}_3\right] / \mathrm{dt}=\mathrm{k}$\left[\mathrm{H}_2\right]\left[\mathrm{N}_2\right]$ The correct statement is- I. The reaction is not elementary. II. The reaction is of second order. III. $-\mathrm{d}\left[\mathrm{H}_2\right] / \mathrm{dt}=-\mathrm{d}\left[\mathrm{NH}_3\right] / \mathrm{dt}$