Statement (b) is incorrect whereas all other statements are correct. (a) Colloidal solution exhibits colligative properties. (b) An ordinary filter paper cannot stop the flow of colloidal particles as the pores are bigger as compared to size of colloidal particles. However, the pores of filter paper can be reduced in size by impregnating with collodion solution to stop the flow of colloidal particles. The usual collodion is a 4% solution of nitrocellulose in a mixture of alcohol and ether. An ultra-filter paper may be prepared by soaking the filter paper in a collodion solution, hardening by formaldehyde and then finally drying it. Thus, by using ultra-filter paper, the colloidal particles are separated from rest of the materials. (c) The flocculating power of Al+3 is more than that of Na+. The greater the valence of the flocculating ion added, the greater is its power to cause precipitation. This is known as Hardy schulze rule. In the coagulation of a negative sol, the flocculating power is in the order Al+3>Ba+2>Na+. (d) When colloidal solutions are viewed under a powerful ultramicroscope, the colloidal particles appear to be in a state of continuous zig-zag motion all over the field of view. This is known as Brownian movement.