What effect does a decrease in temperature have on the overall rate of a chemical reaction? ?

a decreased in temperature decreases ( blank a). the reaction rate will ( blank b).

choices for blank a:
a. the activation energy of the reaction.
b. the number of collisions between molecules.
c. the number of products in the mixture.

choices for blank b:
a. decrease
b. increase
c. remain constant

Change in temperature affects the rate of reaction since it causes a change in the number of collisions per unit time.  These collisions cause the breaking of bonds and formation of new ones  giving out new products. An increase in temperature increases the rate of collisions hence increasing the rate of reaction while a decrease in temperature leads to a decrease in the rate of reaction due to the decreased number of collisions per unit time. thus the correct choice for blank A is: B. the number of collisions between molecules and for blank B: decrease.