The following reaction of 2 Br₂ (g) + 2 NO (g) → N₂ (g) + 2 Br₂O (g) has the following rate law:Rate = k [Br₂][NO]². The proposed mechanism for the reaction is:
Br₂ (g) + NO₂ (g) → N (g) + Br₂O (g)            [SLOW]
N (g)  +  NO (g) → N₂ (g) + O (g)                  [FAST]
O (g)  +  Br₂ (g) → Br₂O (g)                          [FAST]
Which of the following statements is/are false?
a) The rate determining step is bimolecular.
b) There are three elementary steps in the reaction mechanism.
c) The mechanism possesses a catalyst.
d) O is the only reaction intermediate in this reaction mechanism.
e) This is not a valid mechanism for the reaction.

• A. A and B
• B. A, B, and C
• C. A, C, and D
• D. C and D
• E. C, D, and E

Answer: (D)

Verified step by step guidance

1. Identify the rate-determining step in the proposed mechanism. The rate-determining step is the slowest step, which is the first step: Br2 (g) + NO2 (g) → N (g) + Br2O (g).
2. Determine the molecularity of the rate-determining step. Molecularity refers to the number of reactant molecules involved in an elementary step. In this case, the step involves two molecules: Br2 and NO2, making it bimolecular.
3. Count the number of elementary steps in the mechanism. The mechanism consists of three steps: the slow step and two fast steps.
4. Identify any catalysts in the mechanism. A catalyst is a substance that appears in the reactants of an early step and is regenerated in the products of a later step. In this mechanism, there is no such substance, so there is no catalyst.
5. Identify the reaction intermediates. Intermediates are species that are produced in one step and consumed in another. In this mechanism, both N and O are intermediates, as they are produced and consumed within the steps of the mechanism.