MHTCET 15 May 2024 Shift 1 Paper

Concept:The rate constant $k$ is independent of reactant concentrations; only the rate itself depends on concentration.Explanation:The rate constant $k$ is a proportionality factor in the rate law, not a quantity that changes with concentration.Option A is true because $k$ does not depend on concentration for a given reaction at a fixed temperature.Option B is true because $k$ varies with temperature, as shown by the Arrhenius equation $k = A e^{-E_a / RT}$.Option C is true because when the concentration of a reactant is unity, the rate law $r = k[A]^m[B]^n$ simplifies to $r = k$.Option D is false because it is the rate of reaction, not the rate constant, that is directly proportional to the product of concentrations of reacting species.Therefore, the rate constant depends only on factors like temperature and catalyst, not on concentration.Answer:Option D: "It is directly proportional to the product of concentrations of reacting species" is NOT true about the rate constant.