Matter can be broadly divided into two major groups, 'Pure' and 'Impure'. In chemistry, the term 'purity' acquires quite a different meaning from what we understand it to be in our day-to-day life.
A pure substance has the same composition throughout. For example, different samples of water, prepared by different methods, by different people at different places always consist of hydrogen and oxygen in the ratio 1:8 by mass and 2:1 by volume.
Impure substances are commonly called mixtures. A mixture is a material containing two or more elements or compounds that are in close contact and are mixed in any proportion.
The separation of the various constituents of different mixtures depends on the properties of the constituents.
Solution is defined as a homogeneous mixture of two or more chemical substances. The state of matter of a solution may be solid, liquid or gas. For example: common salt in water (liquid solution), air (gaseous solution), alloys (solid solution), etc.
Matter undergoes certain changes as a result of the application of energy. Water from saltpans on the seacoast dry up, leaving behind salt; water from the sea evaporates to from water vapour, which convert into clouds and then condense to form rain.
Solubility is defined as the number of grams of a solute that dissolves in 100g of a solvent to form a saturated solution at a given temperature and pressure.