Question

Protective sols are:
(A) Lyophilic
(B) lyophobic
(C) Both a and b
(D) None of these

Answer 1

Hint : Lyophilic sols are more stable than lyophobic sols, lyophobic sols can be easily coagulated by the addition of a small quantity of an electrolyte. Lyophilic sols are solvent-loving while lyophobic sols are solvent-hating.

Complete Step By Step Answer:
A protective colloid is a lyophilic colloid that when present in small quantities keeps lyophobic colloids from precipitating under the coagulation action of electrolytes. The presence of lyophilic sols is good for lyophobic sols, as when lyophilic sols are added to lyophobic sols, depending on their size, either lyophobic sol is absorbed in the surface of lyophilic sol or lyophilic sol is absorbed on the surface of lyophobic sol. The layer of the protective colloid prevents direct collision between the lyophilic colloid particles and thus prevents coagulation.
The protective actions for different protective sols are defined in terms of gold number. The gold number is the weight in milligrams of a protective sol which checks the coagulation of $ 10ml $ of a given gold sol on adding $ 1ml $ of $ 10\% $ sodium chloride.
Examples- lyophilic sols like starch and gelatin acts as protective colloids.
Option: $ (a)\;Lyophilic $ , is correct option.

Note :
In Lyophilic sols, the dispersed phase shows a positive affinity for the dispersion medium. The high affinity of dispersed particles with the dispersion medium is due to the formation of a large number of hydrogen bonds. Whereas, in lyophobic sols, the dispersed phase does not have any attraction for the dispersion medium.