Question

Which one of the following is a lyophilic colloid?
(A)Gelatin
(B)sulphur
(C)Gold
(D)Carbon

Answer 1

Hint: Liquid loving colloids are known as lyophilic colloids. The word lyo means solvent and the word philic means loving. When lyophilic colloids are mixed with a suitable liquid, there exists a high force of attraction between liquid and the colloidal particles. This will result in the formation of a very stable solution called lyophilic sol.

Complete answer:
The dispersed particles have strong affinity for the dispersion medium in the case of lyophilic colloids. These are stable and also reversible. Lyophilic sols are called hydrophilic sols if water is the dispersion medium. Milk is an example of lyophilic colloid. In milk, solid oil globules are suspended in a water-based liquid system and we can separate the components of milk. Hence, it comes under the category of lyophilic colloids. Gelatin can act as both gel and also as a sol. The colloid is a hydrosol at high temperatures and low concentrations. But at low temperature and high concentration, the hydrosol will convert into gel. This gel is solvent loving and also hydrophilic. Gelatin is a lyophilic colloid.

Therefore, option A is the correct answer.

Note:
The separated dispersed phase and dispersion medium of gelatin can be formed by simply mixing. Colloid particles carry electric charge which is of two types: Positive or negative. Metallic hydroxide sols, haemoglobin, dyestuffs are some of the examples of positively charged sols. Remember that the particles in lyophilic sol absorb ${H^ + }$and $O{H^ - }$ions from the medium.