A chemical analysis is needed.
Any chemical may be pure or impure.
pure
Pure
Salt can be purchased in any form: solid or solution, pure or impure, fine, coarse, etc.
impure
Pure water does not contain colour but impure water contains Other compounds.
Impure naphthalene will typically melt faster than pure naphthalene. The impurities present in impure naphthalene lower its melting point, making it easier for the solid to convert into a liquid state at a lower temperature.
Generally an impure material is cheaper than a pure material; the word advantage is not so adequate here - can use pure or impure, this depends on the specific applications.
The suitable prefix for pure is pure it won't make sense of you put another set of words in front of pure it just would not make
impure
mixture
yes it is true that arteries contain pure blood and veins contain impure blood