5. Give two reasons to support that air is a mixture.

Part 1: Define Mixture

Mixture: When two or more substances (elements or compounds or both) are mixed together in any proportion, in a way that they do not undergo any chemical change, but retain their individual properties, then it is called a mixture. Properties of a mixture:

• In a mixture, the composition is not fixed.
• Mixture constituents can be separated by physical processes such as evaporation, boiling, etc.
• In the formation of a mixture, no chemical process is involved
• Mixture properties will depend upon their individual components.

Part 2: Air is a mixture

The reasons given below will prove that air is a mixture:

• Several gases such as nitrogen, oxygen, carbon dioxide, water vapor, and inert gases are present in the air as their constituents. These constituents are not present in a fixed ratio.
• By the physical process of fractional distillation, air can be separated into its constituents like oxygen, nitrogen, etc
• Air will show the properties of all the gases present in it. And hence it is a mixture of gases.