Colloid - particle size ranges from 1mμ1nm-1μ1000nm   Crystalloid - Urea solution can pass through the membrane easily   True solution - particle size is less than 1mμ1nm can not be observed even with ultramicroscope     Dispersed phase - A dispersed phase can be a solid (or) liquid (or) gas                             which is dispersed in medium to form heterogeneous mixture called colloid