The Maxwell–Boltzmann distributions of molecular kinetic energies for a gaseous reaction mixture at two different temperatures, T1 T_1\,T1 and T2T_2T2, are shown below.
Which of the following is the correct explanation for why the reaction rate is significantly higher at temperature T2 T_2\,T2 than at T1T_1T1?
At T2T_2T2, the activation energy EaE_aEa decreases, shifting the threshold line to the left and increasing the proportion of successful collisions.
At T2T_2T2, the peak of the distribution is lower, meaning the total area under the curve increases and therefore the collision frequency increases.
At T2T_2T2, a much larger fraction of molecules possess kinetic energy greater than or equal to EaE_aEa, significantly increasing the proportion of successful collisions.
At T2T_2T2, the average kinetic energy of the molecules is higher, and the resulting increase in collision frequency is the primary factor driving the increased rate.