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.

[EX Q]: Question: Solvation involves surrounding ions with what? Answer: solvent particles
[EX A]: Solvation involves surrounding ions with solvent particles.

[EX Q]: Question: What causes blue litmus to turn red? Answer: acid
[EX A]: Acids change the color of certain acid-base indicators. Two common indicators are litmus and phenolphthalein. Blue litmus turns red in the presence of an acid, while phenolphthalein turns colorless.

[EX Q]: Question: Where do all cells come from? Answer: pre-existing cells
[EX A]:
All cells come from pre-existing cells.