True
REASON: All gas mixtures are homogeneous, hence all gas mixtures are solutions. Air is an example. Air is only one phase--the gas phase. All the molecules, whatever the source, behave as gas molecules. The molecules themselves may have come from gaseous substances, liquid substances, or solid substances. Whatever the source of the constituents, this gaseous solution–air–is in a single, homogeneous phase. As with other solutions, the constituents of air may be separated by phase changes.
