Explain what is observed when
(i) KCl, an electrolyte, is added to hydrated ferric oxide sol,
(ii) an electric current is passed through a colloidal solution,
(iii) a beam of lights is passed through a colloidal solution.

Explanation

(i) When and electrolyte like KCl is added of Fe `(OH)_(3)` sol, the positively charged coloidal particles of Fe `(OH)_(3)` get coagulated by the oppositely charged `Cl^(-)` ions provied by KCl
(ii) On passing the electric current, colliodal particles move towares the oppositely charged electrode where they lose charged and get coagulated.
(iii) When a beam of strong lights is passed through a colloidal solution scattering of ligth by colloidal particles takesa palce and the path of light becoems visible. This phenomenon is called Tyndall effect