Which one of the following does not involve coagulation?

Identify the correct molecular picture showing what happens at the critical micellar concentration $(CMC)$ of an aqueous solution of a surfactant $(\circ \text{ polar head; } \sim \text{ non-polar tail; } \bullet \text{ water})$.

Smoke is a colloidal dispersion of :-

Detergents $ \text{reduce} $ the surface tension of water.

Which of the following is lyophobic in nature?

Gelatin is a protective colloid for which of the following?