Definition: Given a scientific passage and an answer, generate a question for the given answer.
Input: Passage: Some molecules are not able to satisfy the octet rule by making only single covalent bonds between the atoms. Consider the compound ethene, which has a molecular formula of C 2 H 4 . The carbon atoms are bonded together, with each carbon also being bonded to two hydrogen atoms. Answer: hydrogen
Output:
The carbon atoms are bonded together, with each carbon also being bonded to two of what kind of atoms?