Question

Milk is an example of :
(A) fat dispersed in water
(B) water dispersed in fat
(C) water dispersed in oil
(D) fat dispersed in fat

Answer 1

Hint: Milk is an emulsion with fat particles (globules) dispersed in an aqueous solution. Milk is an example of the oil-in-water type of emulsion.

Complete answer:
An emulsion is a colloid consisting of two or more non-homogenous types of liquids wherein one of the liquids contains the dispersion of the different forms of liquids.
In simple words, emulsions are colloids in which both the dispersed phase and dispersion medium are liquids.
Emulsions can be classified on the basis of the properties of the dispersed phase and the dispersion medium which are of two types:
1) Oil in water (O/W):
In this type of emulsion, the oil will be the dispersed phase and the water \[\left( {{H_2}O} \right)\] will be the dispersion medium. The best example for o/w emulsion is milk. In milk, the fat globules (which acts as the dispersed phase) are suspended in water (which acts as the dispersion medium).
2) Water in oil (W/O):
In this type , water will be the dispersed phase and oil will be the dispersion medium.
Margarine (a spread used for flavouring , baking and working) is an example of water in oil emulsion.
Milk is an example of a colloidal solution in which the dispersed phase is fat and dispersion medium is water.

Therefore the correct answer is option (A) fat dispersed in water.

Note: The fat globules do not coalesce and form a separate layer (oil off or churn) because they are protected by a membrane layer which keeps the fat particles separate from the water phase.