Given scientific fact as input, generate the question from this fact such that it can be answered from the input.
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Question: You call the separation of ions that occurs when a solid ionic compound dissolves dissociation.

Answer: What do you call the separation of ions that occurs when a solid ionic compound dissolves?

Question: Through tubular ducts part do exocrine glands discharge their contents.

Answer: Through what part do exocrine glands discharge their contents?

Question: In physics, resistance is opposition to the flow of electrical charges.

Answer:
In physics, resistance is opposition to the flow of what?