You will be given a definition of a task first, then some input of the task.
Given a scientific passage and an answer, generate a question for the given answer.

Passage: Isotopes with magic numbers of protons and/or neutrons tend to be especially stable. Elements with magic numbers of protons tend to have more stable isotopes than elements that do not. Answer: protons
Output:
Elements with magic numbers of what tend to have more stable isotopes?