Given a scientific question and its correct answer, generate supporting facts for the answer. This supporting fact can be an explanation for the answer to the given question.
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Question: Question: What changes the chemical composition of a substance and can only occur through a chemical reaction? Answer: chemical changes

Answer: Pure substances, such as compounds, can be separated through chemical changes. Chemical changes change the chemical composition of a substance and can only occur through a chemical reaction.

Question: Question: A flow of one coulomb per second is called one ampere, which is a measure of what? Answer: electric current

Answer: The electric current is measured in coulombs per second. A flow of one coulomb per second is called one ampere, A, of current.

Question: Question: How many nonpolar bonds does an oxygen molecule have? Answer: 2

Answer:
An oxygen molecule has two nonpolar bonds. This is called a double bond. The two oxygen atoms attract equally the four shared electrons.