Consider the following representation of a reaction mechanism.
Step 1: Unimolecular (fast)
Step 2: Bimolecular (slow)
Step 3: Unimolecular (fast)
Which conclusion about the rate law for the reaction above is reasonable?
A. It is first order overall because step 1 is unimolecular.
B. It is first order overall because both steps 1 and 3 are unimolecular.
C. It is second order overall because step 2 is bimolecular.