The correct answer is:
(1) Greater number of molecules are having the activation energy (threshold energy).
According to the collision theory of reaction rates, the rate of a chemical reaction depends on the frequency of collisions between reactant molecules and their energy. The collision theory proposes that for a reaction to occur, reactant molecules must collide with sufficient energy (activation energy) and with the correct orientation.
When the temperature of a reaction increases, it leads to an increase in the kinetic energy of the molecules. This higher kinetic energy results in greater molecular motion, increased collision frequency, and more energetic collisions. As a result, a larger number of collisions possess the necessary activation energy to surpass the energy barrier and lead to a successful reaction.
Therefore, an increase in temperature increases the rate of the reaction by providing a greater number of reactant molecules with the required activation energy. This allows more collisions to result in a successful reaction, leading to an overall faster reaction rate.
Option (1) correctly explains the cause behind the increase in the reaction rate with temperature. Options (2) and (3) are indirectly related to the increase in temperature but do not directly address the cause. Option (4) is incorrect because the increase in temperature does have an effect on the reaction rate according to the collision theory.
Hence, the correct answer is (1) Greater number of molecules are having the activation energy (threshold energy). |
