Air is an example of a gas-gas solution, or a solution in which a gaseous solute is dissolved in a gaseous solvent. Air is comprised of multiple gases.
About 78 percent of air is nitrogen, so this element is classified as the solvent. The largest solute in air is oxygen, at 20 percent. Other solutes include argon, carbon dioxide, neon, helium and methane. Some trace solutes include ozone, carbon monoxide and ammonia.
It is also possible to have a solution in which a gas is dissolved in a liquid, such as soda. Sometimes a liquid can be dissolved into a gas, as with water vapor.