Define solution. Give classification of mixtures on the basis of sizes of the components in it.

Solution: A solution is defined as homogeneous mixture of two or more pure substances. 

Classification of mixtures on the basis of sizes of the components- Solutions are mixtures of two or more components. Depending on sizes of the components, the mixtures are classified into two types:

a) A colloidal dispersion: It is formed when sizes of particles dispersed in solvent are in the range of 1 to 1000 nm. E.g. ferric hydroxide sol, arsenic sulphide sol.

b) A true solution: It is obtained when particle size is very small. It is in the order of 0.1 to 1 nm

e.g. aqueous sugar solution or aqueous NaCl solution.