Final answer:
Increasing grid ratio leads to increased density, which in turn decreases molecular movement and diffusion, as there is less space between the molecules for movement.
Step-by-step explanation:
When considering how increasing grid ratio affects density, one must understand that as the density of a liquid decreases, the diffusion constant will increase. This is because lower density means there is more space between the liquid molecules, allowing for more movement. Factors like molecule size and temperature play roles as well. Larger molecules move more slowly than lighter ones, and temperature changes affect the energy in the medium, influencing molecular movement. Conversely, density is inversely proportional to molecular movement. Thus, if density increases (greater grid ratio), we can infer that molecular movement, and therefore diffusion, would decrease due to less space between molecules.