Gas solutions are formed when solids, liquids, or gases dissolve in a gas. An example of a solid dissolving in a gas solution is when iodine (solute) dissolves in air (solvent) to make iodine vapor. When water (solute) dissolves in air (solvent) through the process of evaporation to make water vapor, this is an instance where liquid dissolves into a gas solution. Gas dissolves in a gas to make a solution when nitrogen, oxygen and other gases mix together to form the air that we breathe. Air is therefore a mixture, not a compound.