Identify the option below that exemplifies how the intrinsic chemical properties of a reactant affect the rate of reaction. Select the correct answer below: When exposed to air, sodium reacts completely overnight, whereas iron barely reacts. Five 4-inch diameter saplings burn more rapidly than a 20-inch tree of the same height. Food spoils more quickly on a kitchen counter than in a refrigerator. A Bunsen burner is used in the laboratory to increase the speed of reactions.