Consider the following proposed mechanism for the oxidation of NO:
Step 1 2 NO(g) ⇌ N₂O₂(g) (fast, reaches equilibrium)
Step 2 N₂O₂(g) + O₂(g) → 2 NO₂(g) (slow)
If the initial concentration of NO is doubled while the concentration of O₂ is held constant, which of the following best predicts the resulting change in the initial reaction rate?
a) The rate increases by a factor of 2.
b) The rate increases by a factor of four.
c) The rate remains unchanged.
d) The rate doubles.