Given a scientific question, generate a correct answer to it.

Q: Potential differences from various voltage sources are necessary in order to create electrical fields, which result in what flow of charge?

A: current
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Q: Adding the number of protons plus the number of neutrons in an atom, decides it's approximate mass, what is another word for this value?

A: atomic number
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Q: What causes maple leaves to change their colors?

A:
chemical reactions
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