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

[Q]: 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
[A]: 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?

[Q]: 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
[A]: The number of electrons in the outer energy level determines what property of nonmetals?

[Q]: Passage: Physical and chemical properties of geometric isomers are generally different. While cis -2-butene is a polar molecule, trans -2-butene is nonpolar. Heat or irradiation with light can be used to bring about the conversion of one geometric isomer to another. The input of energy must be large enough to break the pi bond between the two carbon atoms, which is weaker than the sigma bond. At that point, the now single bond is free to rotate and the isomers can interconvert. Answer: different
[A]:
Physical and chemical properties of geometric isomers are generally what?