Which of the following best describes air in terms of classification of matter?

• A. Air is an element because it is made up of atoms of a single type.
• B. Air is a compound because its components are chemically bonded.
• C. Air is a pure substance because it consists of only one type of molecule.
• D. Air is a mixture because it contains several different gases.

Answer: (D)

Verified step by step guidance

1. Recall the definitions of the classifications of matter: an element is a pure substance made of only one type of atom; a compound is a pure substance made of two or more elements chemically bonded together; a mixture contains two or more substances physically combined, not chemically bonded.
2. Consider the composition of air: it is primarily a combination of different gases such as nitrogen, oxygen, argon, carbon dioxide, and others, each existing as separate molecules or atoms.
3. Since the gases in air are not chemically bonded to each other but coexist physically, air does not qualify as a pure substance (element or compound).
4. Therefore, air fits the definition of a mixture because it contains several different gases physically combined without chemical bonds.
5. Conclude that the best classification of air is a mixture, as it is a physical blend of multiple gases rather than a single pure substance.