state some examples of diffusion in solid, gases, liquid
solid - If metallic gold and metallic lead are placed in intimate contact, over a period of time, molecules of lead will diffuse into the gold and vice versa. This has been known for a long period of time.
gases - Your nose is able to detect the smell of the cologne or perfume even if you are quite a distance from the bottle that has been opened.
liquid - a crystal of potassium permanganate in water, watch the colour spread (diffuse out) as the crystal dissolves.