No.
If it's "pure" it's not a mixture.
homogeneous
Pure water (H2O) is a chemical compound; if the water is impure may be a homogeneous or heterogeneous mixture.
They are homogeneous. But they are not a mixture, so they are a pure substance
air is homogeneous
Neither, its a pure substance
seawater is a homogeneous mixture. The water being the solvent and the salt being the solute. A heterogeneous mixture is mixed but not as thoroughly as a homogeneous mixture. None of these though are chemically combined, none are compounds. (hence mixture)
Homogeneous mixture
Pure water (H2O) is a chemical compound; if the water is impure may be a homogeneous or heterogeneous mixture.
Homogeneous mixture
Pure water (H2O) is a chemical compound; if the water is impure may be a homogeneous or heterogeneous mixture.
They are homogeneous. But they are not a mixture, so they are a pure substance
Spring water is not pure water, it has dissolved minerals in it, which makes it a homogeneous mixture.
Silver is not a homogeneous mixture or a heterogeneous mixture, it is a pure element. Silver does appear in homogeneous mixtures and heterogeneous mixtures such as sterling silver and silver nitrate.
air is homogeneous
Heterogeneous vs. homogeneous refers to solutions. Pure water is a compound which is bound together chemically. Solutions are combined physically. So technically it is neither.
pure substance
Pure air is homogeneous because all components are completely miscible.
Neither, its a pure substance