Give reason for the following observations :
(i) When Silver nitrate solution is added to Potassium iodide soltuion , a negatively charge colloidal solution is formed.
(ii) Finely divided substance is more effective as an adsorbent.
(iii) Lyophilic colloid are also called reversible sols.

Explanation

(i) If silver nitrate solution is added to postassium iodide solution, the precipitated Agl will adsorb iodide ions formt the dispersion medium and a negatively charged colloidal solution will form.
(ii) Finely divided substance is more effective as an adsorbent, more effective is the adsorption, more effective is the adsorption.
(iii) Lyophillic colloids are reversible sols because the residue left on evaporation can be readily transferrred back into a colloidal state simply by adding the solvent.