Question

Air is made up of different gases, such as oxygen, nitrogen, and carbon dioxide.

Which statement best describes these three components of air?
Oxygen, nitrogen, and carbon dioxide are all classified as pure substances.
Oxygen, nitrogen, and carbon dioxide cannot react with another substance.
Oxygen, nitrogen, and carbon dioxide are chemically bonded to one another.
Oxygen, nitrogen, and carbon dioxide can be classified as elements.

Answer 1

Oxygen, nitrogen, and carbon dioxide are all classified as pure substances.

Reason: Each is a substance with a definite chemical composition and properties (O2 and N2 are elements, CO2 is a compound). They exist in air as separate molecules in a mixture, not chemically bonded to one another.