• Mixture: Mixtures are formed when two or more substances mixed together without participating in a chemical change.
• Homogeneous Mixtures: A homogeneous mixture is a mixture in which the composition is uniform throughout the mixture. Example: salt in water.
• Heterogeneous Mixture: A heterogeneous mixture is a mixture in which the composition is not uniform throughout the mixture. Eg. Vegetable soup.

Mixture:

• Mixtures are formed when two or more substances mixed together without participating in a chemical change.
• In simple words, a mixture is a material made up of two or more different substances which are physically combined.

Examples of Mixtures:

1. Oil and water
2. Potassium nitrate, sulfur, and carbon (Gunpowder)
3. Minerals, organic materials, air, water, and living organisms (Soil)

General Properties of Mixtures:

• A mixture is a combination of two or more substances that are not chemically combined.
• No chemical change happens when a mixture is made. So, each substance has the same chemical makeup it has before the mixture was formed.
• A mixture is a physical change.
• Each substance in a mixture keeps its identity.
• The substances in a mixture can be separated using physical methods such as filtration, freezing, and distillation.

Types of mixture:

1) Homogeneous Mixtures:

• Homo means same
• A homogeneous mixture is a mixture in which the composition is uniform throughout the mixture.
• Example: salt in water.
• It has a uniform composition and it can’t be separated out physically.

2) Heterogeneous Mixture:

• Hetero means different
• A heterogeneous mixture is a mixture in which the composition is not uniform throughout the mixture. Eg. Vegetable soup.
• It has a non-uniform composition and it can be separated out physically.

Then is air homogeneous or heterogeneous?

It is homogeneous because as its constituents quickly mix in with the other constituents to become uniform (clearly, we do not see different layers of its components)