A container is filled with a mixture of helium (light molecules)and oxygen (heavy molecules)gases.A thermometer in the reads 22°C.Which gas molecules have the greater average speed?
A) It is the same for both of the gases because the temperatures are the same.
B) The oxygen molecules do because they are diatomic.
C) The oxygen molecules do because they are more massive.
D) The helium molecules do because they are less massive.
E) The helium molecules do because they are monatomic.

Question

Quizplus · Accepted Answer

The speed of gas molecules is inversely proportional to their mass. Therefore, lighter gas molecules will have a greater average speed than heavier gas molecules at the same temperature. Since helium is less massive than oxygen, the helium molecules will have a greater average speed. Additionally, the fact that helium is monatomic (consisting of individual atoms) rather than diatomic (consisting of two atoms) like oxygen does give it a slight advantage in speed as well, but mass is the primary factor.

A Container Is Filled with a Mixture of Helium (Light