Question

the picture shows molecules on one side of a permeable membrane.
which indicates that diffusion is complete?
there will be more molecules on the right side than the left side of the membrane.
all the molecules will be on the right side of the membrane.
there will be more molecules on the left side than the right side of the membrane.
there will be an equal number of molecules on each side of the membrane.

Explanation:

Diffusion is the movement of molecules from an area of higher concentration to an area of lower concentration until equilibrium is reached. At equilibrium, the concentration (number of molecules) is equal on both sides of the permeable membrane. The first option suggests a higher concentration on one side, the second implies all molecules move to one side (which isn't how diffusion works as it's about equilibrium, not complete movement to one side), the third also suggests a higher concentration on one side. Only the last option describes equilibrium with equal numbers on each side, indicating diffusion is complete.

Answer:

There will be an equal number of molecules on each side of the membrane.