Question

A gas jar containing air is placed upside down on a gas jar of bromine vapour. It is observed that after some time the gas jar containing air also becomes completely reddish brown. Why this happens. Name the process involved.

Answer 1

Diffusion is the name of this phenomena, it happens in liquids and solids ( Atomic diffusion ) as well although in solids it is a very slow process.
In liquids it is quicker, imagine putting a drop of dye into a bowl of clear water, after a while all the water will be colored.