Give reason for the following.
Brownian movement of colloidal particles.

Explanation

(i) The reason for the Brownian movement of colloidal particles is the collisions of the constantly moving dispersion medium particles. During collision, colloidal particles acquire kinetic energy. Due to larger size compared to dispersion medium particles, colloidal particles move slowly in a zig-zag manner.
(ii) The reason for the stability of colloids is the presence of equal and similar charges on the colloidal particles. The repulsive forces between charged particles having same charge prevent them from aggregating when they come closer to one another.
(iii) The movement of colloidal particles towards cathode is due to the presence positive charges on the colloidal particles.