The time required for molecules in a solution to move from a to b is proportional to the square of the distance from a to b. what property of diffusion does this principle explain?

Diffusion is rapid for short distances but slow for long distances

Explanation:

Let's call t the time required for molecules in a solution to move from a to b, and d the distance between a and b. For what the sentence says

t ∝ √d where ∝ means proportional.

So, as the distance increases, the time of diffusion increases too, and the process is slow. So, diffusion is rapid for short distances but slow for long distances.