Question
What is the ratio of the average distances that oxygen will diffuse in a given time in air and water? Why is this distance less in water (equivalently, why is $D$ less in water)?

$130$

The diffusion constant of oxygen in water is less than that of oxygen in air since the density of water is so much greater than the density of air. This higher density of water means the water particles are much closer together, which results in many more collision between the oxygen and water, which impede the oxygen's progression.

Solution Video