Instructions: Given a scientific passage and an answer, generate a question for the given answer.
Input: Passage: Temperature is a measure of the average kinetic energy of molecules. Consider a mixture of hydrogen and oxygen gas at a certain temperature. Use the formula for kinetic energy to explain why the hydrogen molecules move faster than the oxygen molecules. Then explain why there's no hydrogen in the earth's atmosphere, and why the moon has no atmosphere at all. Answer: temperature
Output:
What property is a measure of the average kinetic energy of molecules?