The protecting power of lyophilic colloidal sol is expressed in terms of
(a) coagulation value
(b) gold number
(c) critical micelle concentration
(d) oxidation number
Lyophobic sols are unstable, so they are stabilised by adding some lyophilic colloids which protect them from precipitation. Thus, lyophilic colloids are called protecting colloids. Their protecting power is expressed in terms of gold number.
Note: Lesser the gold number, higher is the protecting power