Write scientific reason.
Constituent substances of a colloid cannot be separated by ordinary filtration.
Constituent substances of a colloid cannot be separated by ordinary filtration because the size of the particles in a colloids(or colloidal solution) is bigger than those in a true solution but smaller than those in suspension.It is in between 1nm to 100nm in diameter. The size of ordinary filter paper is more than 100nm due to which colloidal particles are passed through the pores of a filter paper. Due to which, we prefer to use ultrafilter paper so that, filteration of colloidal particles take place easily.