The air in your room is composed mostly of oxygen (O2) and nitrogen (N2) molecules. The oxygen molecules are more massive than the nitrogen molecules.

(a) Is the rms speed of the O2 molecules greater than, less than, or equal to the rms speed of the N2 molecules?

(b) Choose the best explanation from among the following:

I. The more massive oxygen molecules have greater momentum and therefore greater speed.

II. Equal temperatures for the oxygen and nitrogen molecules imply they have equal rms speeds.

III. The temperature is the same for both molecules, and hence their average kinetic energies are equal. As a result, the more massive oxygen molecules have lower speeds?