Given a scientific passage and an answer, generate a question for the given answer.

Q: Passage: and procaine. Not only do catalysts greatly increase the rates of reactions, but in some cases such as in petroleum refining, they also control which products are formed. The acceleration of a reaction by a catalyst is called catalysis. Answer: reactions

A: Catalysts can greatly increase the rates of chemical what?
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Q: Passage: rates The rates at which reactants are consumed and products are formed during chemical reactions vary greatly. We can identify five factors that affect the rates of chemical reactions: the chemical nature of the reacting substances, the state of subdivision (one large lump versus many small particles) of the reactants, the temperature of the reactants, the concentration of the reactants, and the presence of a catalyst. Answer: catalyst

A: The presence of what, which acts as a trigger, affects the rate of chemical reaction?
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Q: Passage: Solids can be divided into amorphous solids and crystalline solids. Answer: crystalline solids

A:
Solids can be divided into amorphous solids and which other group?
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