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

Input: Consider Input: Passage: Coal is the source of most electricity. Answer: coal

Output: What is the source of most electricity?

Input: Consider Input: Passage: Molecular compounds are inorganic compounds that take the form of discrete molecules . Examples include such familiar substance as water (H 2 O) and carbon dioxide (CO 2 ). These compounds are very different from ionic compounds like sodium chloride (NaCl). Ionic compounds are formed when metal atoms lose one or more of their electrons to nonmetal atoms. The resulting cations and anions are electrostatically attracted to each other. Answer: molecular compounds

Output: What are inorganic compounds that take the form of discrete molecules called?

Input: Consider Input: Passage: An asteroid can only change due to a collision. A collision may cause the asteroid to break up. It may create craters on the asteroid's surface. An asteroid may strike a planet if it comes near enough to be pulled in by its gravity. Answer: a collision
Output: What is the only thing that can change an asteroid?