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.

Explanation:

1. Pure substances have a definite and constant composition. Oxygen ($O_2$), nitrogen ($N_2$) and carbon - dioxide ($CO_2$) each have a fixed chemical composition, so they are pure substances.
2. Oxygen can react with many substances in oxidation - reduction reactions, nitrogen can participate in certain chemical reactions under specific conditions, and carbon dioxide can also react with substances like calcium hydroxide, so the statement that they cannot react with other substances is wrong.
3. In air, oxygen, nitrogen and carbon dioxide are just mixed together physically, not chemically bonded to one another.
4. Oxygen and nitrogen are elements, but carbon dioxide is a compound composed of carbon and oxygen elements.

Answer:

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