Explain what is observed
(a) When an electrolyte NaCl is added to ferric hydroxide sol.
(b) When an emulsion is subjected to centrifugation.
(c) When direct currect is passed through a colloidal sol.
(d) When a beam of light is passes through a colloidal solution.

Answer

(a) Positively charged colloidal particles of `Fe(OH)_(3)` get coagulated by the oppositely charged `Cl^(-)` ions provided by NaCl.
(b) Constituent liquids of the emulsion separate out i.e., demulsification occurs.
(c) Colloidal particles move towards the oppositely charged electrodes, where they lose their charge and get coagulated.
(d)Scattering of light by the colloidal particles takes place and the path and the path of light becomes visible (Tyndall effect).