Question

the diagram shows the same type of molecules in area a and area b. what would you expect to happen to the molecules over time?
molecules
selectively permeable membrane
molecules on side b will move to side a to reach equilibrium.
molecules on side a will move to side b to reach equilibrium.
the molecules will remain in their designated space, no change will occur.
all of the molecules will move to side a since they already have the highest concentration.

Explanation:

This is a diffusion - related question. Diffusion is the movement of molecules from an area of higher concentration to an area of lower concentration until equilibrium (equal concentration on both sides) is reached. From the diagram, area A has a higher concentration of molecules than area B. The selectively permeable membrane allows these molecules to pass through. So, the molecules will move from the higher - concentration area (A) to the lower - concentration area (B) to achieve equilibrium. Option A is incorrect because molecules move from high to low concentration, not the other way around. Option C is incorrect as diffusion will occur to reach equilibrium. Option D is incorrect as molecules will move to spread out and reach equilibrium, not all move to the already high - concentration side.

Answer:

B. Molecules on side A will move to side B to reach equilibrium.