If the atmosphere of a particular planet is at a temperature of 213 K (-60°C), then molecules of methane (CH₄) and molecules of carbon dioxide (CO₂) in this atmosphere have: A)different average speed and kinetic energy. B)the same average kinetic energy (but different average speed). C)the same average speed (but different average kinetic energy). D)the same average speed and kinetic energy.

Question

Quizplus · Accepted Answer

At a given temperature, all gases have the same average kinetic energy, which is proportional to the temperature. Therefore, both methane and carbon dioxide molecules in the atmosphere will have the same average kinetic energy. However, their molecular masses are different, so they will have different average speeds. This means that option B is correct, as the molecules have the same average kinetic energy but different average speeds.

If the Atmosphere of a Particular Planet Is at a Temperature