Final answer:
The molecularity of the reaction 2 NO₂(g) → N₂O₄(g) is bimolecular, option b) , involving two molecules of NO₂.The reaction 2 NO₂(g) → N₂O₄(g) is bimolecular, involving two NO₂ molecules colliding in a single elementary step.
Step-by-step explanation:
The molecularity of a reaction is a term used to describe the number of molecules that participate in an elementary step of a reaction. For the reaction 2 NO₂(g) → N₂O₄(g), it represents a single step in which two molecules of NO₂ collide to form one molecule of N₂O₄. Therefore, this reaction is bimolecular, meaning it involves two molecules colliding.
It is important to distinguish molecularity from the stoichiometry of the overall reaction which could involve many steps. In this case, even though the reaction 2NO(g) + O₂(g) → 2NO₂ might appear to be termolecular, it actually proceeds via two steps, each with its own molecularity. The key is to look at the elementary step, not the overall reaction.