Explain what is observed,
(i) when a beam of light is passed through a colloidal solution?
(ii) when an electrolyte, NaCl, is added to hydrated ferric oxide solution?
(iii) electric current is passed through a colloidal solution?
(i) When a beam of light is passed through a sol, scattering of light takes place and the path of light becomes visible (Tyndall effect).
(ii) Charge on ferric ion is neutralised by chloride ions. Thus,coagulation takes-place.
(iii) When electric current is passed through a sol, the colloidal particles move towards the oppositely charged electrode and the phenomenon is called electrophoresis.