Read the given passage and answer the questions
A substance which alters the rate of chemical reaction without undergoing any change in mass and chemical composition at the end of reaction is called catalyst. It may be noted that catalyst which increases the speed of a reaction is called positive catalyst and catalyst which decrease the speed of reaction is called negative catalyst. The promoters are substances that enhance the activity of catalyst and poisons are the substances which decrease the activity of catalyts.
What are promoters ?