Given a scientific passage and an answer, generate a question for the given answer.

Ex Input:
Passage: Some nonmetals are very reactive, whereas others are not reactive at all. It depends on the number of electrons in their outer energy level. Answer: reactivity

Ex Output:
The number of electrons in the outer energy level determines what property of nonmetals?

Ex Input:
Passage: Cycloalkanes are hydrocarbons whose molecules are closed rings rather than straight or branched chains. A cyclic hydrocarbon is a hydrocarbon with a ring of carbon atoms. Answer: carbon atoms

Ex Output:
Cycloalkanes are hydrocarbons whose molecules are closed rings rather than straight or branched chains. a cyclic hydrocarbon is a hydrocarbon with a ring of these?

Ex Input:
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

Ex Output:
Elements with magic numbers of what tend to have more stable isotopes?