Given scientific fact as input, generate the question from this fact such that it can be answered from the input.

Example Input: The combustion of propane gas produces carbon dioxide and water vapor.
Example Output: The combustion of propane gas produces carbon dioxide and what else?

Example Input: Metallic bonds gives a coil of copper wire the ability to conduct electricity well.
Example Output: What gives a coil of copper wire the ability to conduct electricity well?

Example Input: The main difference between eukaryotic and prokaryotic cells is that eukaryotic cells have a nucleus.
Example Output:
What is the main difference between eukaryotic and prokaryotic cells?