From the following statement regarding the order of reaction, the statement that is not true is
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → For complex reaction, order is given by the fastest step
- Order of reaction is an experimental quantity: Order cannot be determined directly from the balanced chemical equation. It is determined experimentally from rate law studies. Therefore, this statement is true.
- The order of a reaction can be zero or even a fraction: Reaction order may be zero, fractional, or even negative depending on the reaction mechanism. Therefore, this statement is true.
- Order of reaction is applicable to elementary reaction: For elementary reactions, the order is equal to the molecularity because the reaction occurs in a single step. Therefore, this statement is true.
- For complex reaction, order is given by the fastest step: In complex reactions, the overall rate is determined by the slowest step (rate-determining step), not the fastest step. Thus, this statement is incorrect.