Given a scientific passage and an answer, generate a question for the given answer.
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Question: Passage: Water is the main ingredient of many solutions. A solution is a mixture of two or more substances that has the same composition throughout. Some solutions are acids and some are bases. To understand acids and bases, you need to know more about pure water. In pure water (such as distilled water), a tiny fraction of water molecules naturally breaks down to form ions. An ion is an electrically charged atom or molecule. The breakdown of water is represented by the chemical equation. Answer: solution

Answer: What is the term for a mixture of two or more substances that has the same composition throughout?

Question: Passage: Oxygen has the second highest electronegativity of any element; consequently, it prefers to share or accept electrons from other elements. Only with fluorine does oxygen form compounds in positive oxidation states. Answer: positive oxidation states

Answer: Oxygen has the second highest electronegativity of any element; consequently, it prefers to share or accept electrons from other elements. only with fluorine does oxygen form compounds in this?

Question: Passage: Regardless of what gravity is a force between masses or the result of curves in space and time the effects of gravity on motion are well known. You already know that gravity causes objects to fall down to the ground. Gravity affects the motion of objects in other ways as well. Answer: gravity

Answer:
What is the force that causes objects to fall down to the ground?