Question

Peptisation involves:
$(i)$ Precipitation of colloidal particles
$(ii)$ Disintegration of colloidal integrates
$(iii)$ Evaporation of dispersion medium
$(iv)$ Impact of molecules of the dispersion medium on the colloidal particles

Answer 1

To answer this question we need to understand the process of peptisation. The process of peptisation is reverse to the process of flocculation. This is why sometimes we call peptisation as deflocculation. In peptisation we convert the precipitate into a colloidal solution with the help of certain means.

Complete answer:
Peptisation is the process of converting the precipitate into colloidal solution by adding an agent called peptising agent. During the process of coagulation, the solid particles of the colloidal solution aggregate and settle at the bottom of the container. This settled aggregate is also known as precipitate. Now when we want to disintegrate these settled particles we add a certain agent which disintegrates these settled particles and hence we get the colloidal solution. During the process of peptisation the aggregated particles start disintegrating into fine particles of colloidal size and mix with liquid. When these particles get mixed with the liquid, then the solution we get is called a colloidal solution. The size of the fine particles must be in order of ${10^{ - 9}}{\text{ m}}$ to ${10^{ - 3}}{\text{ m}}$. In Flocculation of particles, the aggregate of particles comes at the surface of the liquid rather than settling at bottom which happens in coagulation of colloidal particles.
Therefore the correct option is $(ii)$ Disintegration of colloidal integrals.

Note:
Peptisation is different from coagulation. In coagulation the colloidal particles get aggregated and settle at the bottom of the container forming a precipitate. While in peptisation this precipitate disintegrates into colloidal size particles. In flocculation the aggregate of particles comes to the surface of water.