Given a scientific passage and an answer, generate a question for the given answer.
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Question: Passage: If water is so simple, why is it special? Water is one of the few substances that exists on Earth in all three states of matter. Water occurs as a gas, a liquid and a solid. You drink liquid water and use it to shower. You breathe gaseous water vapor in the air. You may go ice skating on a pond covered with solid water ice in the winter. Answer: three matter states

Answer: In how many states does water exist on earth?

Question: 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

Answer: Catalysts can greatly increase the rates of chemical what?

Question: Passage: The metal part of the compound is named as the element. Answer: the element

Answer:
What is the metal part of the compound named as?