A mixture is a substance with a variable composition, meaning that it is composed of molecules or atoms of differing types.

What has a varying composition?

A heterogeneous mixture is a mixture in which the composition is not uniform throughout the mixture. Vegetable soup is a heterogeneous mixture. Any given spoonful of soup will contain varying amounts of the different vegetables and other components of the soup.

Does a mixture have a varied composition?

Mixtures have variable compositions, while compounds have a fixed, definite formula. When mixed, individual substances keep their properties in a mixture, while if they form a compound their properties can change.