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

Input: Consider Input: Carbon 14 isotope of carbon is typically used to date ancient items.

Output: What isotope of carbon is typically used to date ancient items?


Input: Consider Input: Limestone is insoluble in water, so acid can dissolve it.

Output: Limestone is insoluble in water, so what can dissolve it?


Input: Consider Input: Neon has more electrons, neon or fluorine.


Output: Which has more electrons, neon or fluorine?