(a)Homogeneous mixture: The mixtures in which the substances are completely mixed together and are indistinguishable from each other are called homogeneous mixtures. A homogeneous mixture has a uniform composition throughout its mass. It has no visible boundaries of separation between the various constituents. A mixture of two or more miscible liquids is also a homogeneous mixture. For example, a mixture of alcohol and water is a homogeneous mixture. All the homogeneous mixtures are called solutions. They consist of only one phase. For example, sugar and water mix together to form a homogeneous mixture called sugar solution. There is no visible boundary of separation between sugar and water particles in a sugar solution.

(b) Heterogeneous mixture: A mixtures which does not have a uniform composition throughout its mass. It has visible boundaries of separation between the various constituents. The constituents of a heterogeneous mixture can usually be seen easily. They consist of more than one phase. For example, a mixture of water and sand is a heterogenous mixture. A mixture of sugar and sand is also a heterogenous mixture because different parts of this mixture will have different composition of sugar and sand. Some parts of this mixture will have more sugar particles whereas other parts may have more of sand particles. There is a visible boundary of separation between sugar and sand particles. The suspensions of solids in liquids are also heterogeneous mixtures. For example, a suspension of chalk in water is a heterogeneous mixture. A mixture of two or more immiscible liquids is also a heterogeneous mixture. For example, a mixture of petrol and water is a heterogeneous mixture.