Please Help!

(adding the text here for future search-ability of the problem)

When the rate of the reaction 2 NO (g) + O 2 (g) --> 2 NO 2 (g)

was studied, it was found that the rate doubled when the O 2 concentration alone was doubled, but quadrupled when the NO concentration alone was doubled. Which of the following mechanisms accounts for these observations?

3. When the rate of the reaction 2NO(g)+O2(g)2NO2(g) was studied, it was found that the rate doubled when the O2 concentration alone was doubled, but quadrupled when the NO concentration alone was doubled. Which of the following mechanisms accounts for these observations? i) Step 1: NO+O2NO3 and its reverse (both fast, equilibrium) Step 2: NO+NO3NO2+NO2 (slow) ii) Step 1: NO+NON2O2 (slow) Step 2: O2+N2O2N2O4 (fast) Step 3: N2O4NO2+NO2 (fast) a) Write the rate law for what is observed in the experiment. b) For mechanism i, which step is rate-determining? c) Write the rate law for that step. Identify any intermediates present and substitute for the intermediate in the rate equation for that step. d) Using the same process, show that the rate law obtained for mechanism ii is not consistent with that observed