Explanation:
A mixture is defined as the substance that contains two or more different number of substances that are physically mixed together.
For example, a mixture of air which contains oxygen, nitrogen and other gases.
A mixture in which solute particles are unevenly distributed into the solvent then it is known as a heterogeneous mixture.
For example, sand in water is a heterogeneous mixture.
A homogeneous mixture is defined as the mixture in which solute particles are evenly distributed in a solvent.
A homogeneous mixture is a clear solution.
For example, salt dissolved in water is a homogeneous mixture.
A solution is defined as the substance in which two or more substances are mixed together.
A compound is defined as the substance that contains two or more different elements that chemically combined together in a fixed ratio by mass.
A element is defined as the substance that contains only one type of atoms.
For example, a piece of sodium element will contain only atoms of sodium.
Whereas a pure substance is defined as the substance which contains only one type of molecule or one type of atom.
For example, 
, 
etc are pure substances.
Thus, we can conclude that the terms which could be used to describe the given sample of air is as follows.
