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: Ionic compounds contain cations and anions rather than discrete neutral molecules.

Answer: Ionic compounds contain cations and anions rather than what?

Question: A collapsing nebula leads to nuclear fusion process.

Answer: A collapsing nebula leads to what process?

Question: A cell wall is found in a plant cell but not in an animal cell.

Answer:
Which structure is found in a plant cell but not in an animal cell?