Answer:
Molecules start out unevenly distributed and end up evenly distributed.
Step-by-step explanation:
Diffusion is the process by which molecules of a substance move from a region of higher concentration to a region of lower concentration until equilibrium is attained.
Molecules start out unevenly distributed and end up evenly distributed in a particular medium. Diffusion occurs due to the particulate nature of matter. When the particles that make up a substance are concentrated at a point, the collide more often with one another causing each molecule to spread out in order to occupy all the available space.
Diffusion occurs in gases, liquids and solids but occurs fastest in gases. Diffusion can be observed for example, in the spread of the smell of a dead rat from one point in a room to every part of the room.