A solution is homogeneous mixture of two or more substances. The proportion of the constituents of the solution can be varied within certain limits. The solutions comprising the two components are called binary solutions . That component of a solution which is in the same physical state (.e., Solid, liquid or gas) as the solution is called solvent , and the other component is called solute . If both the components are in the same state, the component which is present in larger proportions is called solvent and the one which is present in minor proportions is called solute. Classification of solutions Depending on the physical states of the solute and the solvent, solutions can be classified into various types. Solvents Solute When the solvent is a gas and the solute is a solid or a liquid, the resultant mixture becomes heterogeneous. All other solutions being homogeneous are called true solutions . The other two types of mixtures being heterogeneous are ...