A pure substance is made up of a single element type
Pure substances are any single substance which have not taken part in chemical reactions. These are usually elements, but they can also be compounds (some examples of pure compounds are H2O,CuSO4,NH4Cl,NH3
pure substances are essential as they ensure the safety of consumers
Normally in chemistry pure substances mean elements. But it can give many other general sense but in deep chemistry pure give meaning of those things which have not taken part in chemical reaction. Elements are defined as the purest substance in chemistry.