Elementary and Complex Reactions MCQ - Practice Questions with Answers

Complex reactions are those reactions when a sequence of elementary reactions or single-step reactions gives us the products. Since the complex reactions occur in multiple steps thus, molecularity for such reactions cannot be determined. It can only be determined for elementary reactions.
For example:

The rate of the reaction is given experimentally as follows:

Now, clearly the order of this reaction is 2 but since it is a complex reaction, thus the molecularity of this reaction cannot be determined.

NOTE: For any complex or elementary reaction, it has been found that:

Because the probability of simultaneous and effective collision of three molecules is very low. Thus, termolecular or higher molecularity reaction is rarely observed.

Difference between Order of Reaction and Molecularity