Question

Milk is an emulsion in which :
A . a gas is dispersed in water
B . lactose is dispersed in water
C . milk fat is dispersed in water
D . a solid is dispersed in water

Answer 1

Hint : We can define emulsion as the mixture of two liquids and one of the liquids is immiscible liquid which means that the liquids would not mix .These are colloids where both phases are liquids .They possess a milky appearance. With the use of an emulsifier stable emulsion can be formed. Stable emulsion means it would not be separated with the change in conditions like temperature and time.

Complete answer:
> Emulsions are very useful in the pharmaceutical industry .Emulsions are used to make medicines more palatable (pleasant taste ).It is also used in skin care products to lock moisture and hydration of skin. It is a colloidal solution where dispersion and dispersed medium both are liquid.
> The word emulsion is taken from the Latin words emulgere and emulsum which means milk .Milk is an emulsion where butterfat globules are suspended in water. Casein which is a lyophilic sol which stabilizes the milk emulsion so it acts as a emulsifier for milk. Milk is an oil in water type emulsion because in milk fat globules are dispersed in water. Hence in the given problem option C is correct which Milk is an emulsion in which milk fat is dispersed in water.

Note : The emulsion has physical properties that differ from its two components . The tactile and spreading properties of emulsions are different from its components . As we know that there are mainly two types of emulsion oil-in-water $(O/W)$ and water -in-oil $(W/O)$.Hence milk is an oil-in-water type emulsion because in case of milk fat dispersed in water.