Air is an example of a ______.

A. solid in gas mixture

B. liquid in gas mixture

C. gas in gas mixture

D. liquid in liquid mixture

Air is primarily made up of nitrogen, oxygen, argon, and carbon dioxide, with other gases present in very small amounts. Nitrogen makes up about 78% of air, while oxygen accounts for around 21%. The remaining 1% consists of all other trace gases.

Since nitrogen is the most abundant, it can be considered the solvent, and oxygen, the solute. Both nitrogen and oxygen exist in the gas phase under normal conditions that support life. Therefore, air can be described as a gas-gas mixture. Additionally, air can also be considered a solution because its components are not easily separable, largely due to its vast quantity and the presence of various trace elements.

Thus, the correct answer is Option C.