Oxygen gas diffuses faster than air. This is because the oxygen molecules are smaller than the air molecules. The smaller the molecules, the faster they can diffuse.

Diffusion is the movement of molecules from an area of high concentration to an area of low concentration. The rate of diffusion is determined by the size of the molecules, the temperature, and the concentration gradient.

The temperature affects the rate of diffusion because the molecules move faster at higher temperatures. The concentration gradient affects the rate of diffusion because the molecules will diffuse more quickly from an area of high concentration to an area of low concentration.

In the case of oxygen gas and air, the oxygen molecules are smaller than the air molecules, so they can diffuse more quickly. Additionally, the concentration gradient of oxygen gas is typically higher than the concentration gradient of air, so the oxygen molecules will diffuse more quickly.

As a result, oxygen gas diffuses faster than air.