(i) Differentitate between adsorbtion and absorption.
(ii) Out of `MgCl_(2)` and `AlCl_(3)`, which one is more effective in causing coagulation of negatively charged sol and why?
(iii) Out of sulphur sol and proteins, which one forms multimolecular colloids?

Explanation

(i) Adsorption is a surface phenomenon, whereas, Absorption is a bulk phenomenon. In Adsorption, the concentration on surface is different from that in bulk, whereas, the concentration is same throughout the material in absorption.
(ii) `AlCl_(3)` is more effective in causing coagulation of negatively charged sol because greater the valency of coagulating ion, greater its power to bring coagulation. `(Al^(3+)gtMg^(2+))`
(iii) Sulphur sol forms multimolecular colloids.