Question

Method by which lyophobic sol can be protected is:
A. By addition of oppositely charged sol
B. By addition of an electrolyte
C. By addition of lyophilic sol
D. By boiling

Answer 1

Hint: Lyophobic sols, and lyophilic sols are categorised under the colloidal sols. Lyophobic sols cannot be prepared by the simple formation of substances like lyophilic sols. In consideration with the given options relating it to the lyophobic sols, method can be determined.

Complete step by step answer:
-Now, first let us define the lyophobic sols. As mentioned it cannot be prepared by simple mixing; it is prepared when a small amount of electrolyte is added.
-So, we can say that an addition of an electrolyte is used to form the lyophobic sols.
-Now, if we talk about the charged sol; then due to the presence of charged particles, the sol will be easily coagulated.
-As we know that lyophobic sols are less than the lyophilic sols due to the strong interaction of dispersed phase, and the dispersion medium in the lyophilic sols.
-We know that lyophilic colloids are known as the protective colloids; because in addition to the lyophobic sol, they protect them from the electrolytes by the formation of a layer.
-Now, the boiling is used to form the lyophobic sols, as these cannot be prepared by mixing.
-Thus, in the last we can conclude that the method by which lyophobic sol can be protected is by the addition of lyophilic sol.

Hence, the correct option is (C).

Note: There could be a confusion as to why we need to protect the sols from the electrolyte. As we know for the coagulation, the charge particles are required. The addition of electrolyte can remove the charge, and it forms precipitates.