Decreasing the temperature of a reaction decreases the reaction rate because a) decreasing the temperature also decreases the pressure. b) decreasing the temperature may cause a reactant to solidify. c) decreasing the temperature decreases the concentration of reactants. d) decreasing the temperature lowers the average kinetic energy of the reactants.

D) decreasing the temperature lowers the average kinetic energy of the reactants.

Explanation:

Rate of a reaction decreases on decreasing the temperature because the energy of the reactant decreases and thus less molecules can cross the energy barrier.

Average kinetic energy is defined as the average of the kinetic energies of all the particles present in a system. It is determined by the equation:

From above, it is visible that kinetic energy is directly related to the temperature of the system. So, if temperature is less, average kinetic energy of the system is less and thus rate decreases.