Which of the following sols are relativity difficult to coagulate?

Options

A. (i), (iii)
B. (ii), (iii)
C. (i), (ii)
D. (iii), (iv)

Answer

B

Explanation

Because there are two factors which are responsible for the stability of lyophilic sols. These factors are the charge and solvation of the colloidal particles. When these two factors are removed a lyophilic sol can be coagulated. This is done (i) by adding an electrolyte and (ii) by adding a suitable solvent. When solvents such as alcohol and acetone are addsd to hydrophilic sols, the dehyration of dispersed phase occurs. Under this condition a small quantity of electrolyte can bring about coagulation.