Tammy puts one toe into the swimming pool and shivers because the water is so cold. She grits her teeth and dives in anyway. After about ten minutes in the water, the temperature seems quite comfortable to her. This example illustrates the principle of:

the answer is c) abandoned properties that are contaminated with hazardous materials.

it provides an alternative energy pathway for the reaction to proceed.

a catalyst is a substance that speeds up the rate of a chemical reaction but is not consumed during the course of the reaction.

catalysts increase the rate of reaction without being used up. they do this by lowering the activation energy needed. with a catalyst, more collisions result in a reaction, so the rate of reaction increases. different reactions need different catalysts.

a catalyst works by providing an alternative reaction pathway to the reaction product. the rate of the reaction is increased as this alternative route has a lower activation energy than the reaction route not mediated by the catalyst.