Match Column I with Column II

i-d; ii-c; iii-a; iv-b

The correct answer is option 1. i-d; ii-c; iii-a; iv-b.

Let us delve into each process and its corresponding function:

i. Dialysis -d. Purification 

Dialysis is a process used to separate colloidal particles from true solution or from finely divided particles of a solid, by allowing them to pass through a semipermeable membrane. In this process, a semipermeable membrane separates the colloidal solution from the dissolved substances or smaller particles. The colloidal particles are retained on one side of the membrane, while the smaller molecules or ions are allowed to pass through. This results in the purification of the colloidal solution.

ii. Peptization - c. Colloidal sol formation 

Peptization is the process of converting a precipitate into a stable colloidal sol by adding a suitable electrolyte or dispersing agent. During peptization, the precipitate aggregates are broken down into individual colloidal particles, which disperse uniformly in the dispersion medium to form a stable colloidal sol. This process is essential for the formation of colloidal sols from precipitates, thereby enabling the particles to remain dispersed without reaggregation.

iii. Emulsification - a. Cleansing action of soap 

Emulsification is the process of dispersing one liquid into another immiscible liquid to form an emulsion. In the context of soap, emulsification refers to the ability of soap molecules to disperse oily substances (such as grease or dirt) in water to form an emulsion. Soap molecules have both hydrophilic (water-attracting) and hydrophobic (water-repelling) ends. The hydrophilic end attaches to water molecules, while the hydrophobic end attaches to oily substances. This allows the oily substances to be dispersed in water as tiny droplets, which can then be rinsed away, facilitating the cleansing action of soap.

iv. Electrophoresis - b. Coagulation 

Electrophoresis is a technique used to separate charged particles (such as colloidal particles or proteins) based on their charge and size, under the influence of an electric field. In the context of coagulation, electrophoresis can be used to induce coagulation or precipitation of colloidal particles by subjecting them to an electric field. When colloidal particles with opposite charges migrate towards each other under the influence of the electric field, they may collide and coalesce, leading to the formation of larger aggregates or precipitates, a process known as coagulation.

These processes play crucial roles in colloidal chemistry and have diverse applications ranging from purification and sol formation to emulsion formation and particle separation.