Question

An example of lyophilic colloid is:
A.colloidal solutions of metal
B.sulphur in water
C.gelatin
D.$Fe{(OH)}_3$

Answer 1

Hint: Lyophilic colloids are the liquid loving colloids. Lyo means liquid and philic means loving hence liquid loving. These are reversible sols as these sols can be separated from dispersed medium through evaporation.

Complete step by step answer:
-A colloid can be defined as a phase separated mixture in which one substance one substance of a microscopically soluble or insoluble dispersed particle is suspended throughout another substance.
-Every colloid consists of two parts: the colloidal particles and the dispersing medium. The colloids can be of two types. These are lyophobic colloids and lyophilic colloids.
-Lyophobic colloids are the colloidal solution in which the dispersed phase has very little affinity for the dispersion medium.
-Lyophilic colloids are the colloidal solution in which the dispersed phase or the particles have a very strong affinity with the liquid.
-The solution of a lyophilic colloid is known as lyophilic sol and can be easily prepared by directly mixing the colloid with the liquid. The lyophilic colloids are very stable in nature and don't precipitate easily.
-In the lyophilic colloids, there is a strong attraction between the dispersed particles and the dispersion medium. Starch, gum, gelatin, RBC, egg albumin etc are the examples of lyophilic colloids.
So, now let us look into the options provided to us in the question.
Among these, only gelatin is an example of lyophilic colloids whereas, colloidal solution of metals, sulphur in water are lyophobic colloids.

Hence, the correct answer is option (c).

Note: Lyophilic colloids are formed spontaneously. These are thermodynamically stable. Their viscosity is more than that of the medium. They cannot be coagulated easily. But with the addition of very large quantities of electrolytes can cause particles to precipitate.