An
inert gas is a gas which does not undergo chemical reactions under a set of given conditions. The
noble gases often do not react with many substances. Inert gases are used generally to avoid unwanted chemical reactions degrading a sample. These undesirable chemical reactions are often
oxidation and
hydrolysis reactions with the oxygen and moisture in
air. The term
inert gas is context-dependent because several of the noble gases can be made to react under certain conditions.