Question

Hair cream is an example of:
A. gel
B. sol
C. aerosol
D. emulsion

Answer 1

Hint: Hair cream comes under the category of colloidal dispersion or colloids. Between suspensions and solutions, there are particles which come under colloids. The difference in colloids and solutions mainly lies in the difference of the particle size. The range of diameters of colloidal particles is between 1 and 1000 nanometers.

Complete step by step answer:
Colloids are a heterogeneous mixture which has one substance as dispersed in another substance. The one which is dispersed is called the dispersed phase and in which it is dispersed is called dispersion medium. Let us discuss the options and the types of colloidal systems, depending whether dispersed phase and dispersion medium are solids, gas and liquids. When gas is mixed with another gas, a homogeneous mixture is formed. The types of colloidal systems are based on the physical state of dispersed phase and dispersion medium:

S. No.	TYPE OF COLLOIDS	DISPERSED PHASE	DISPERSION MEDIUM	EXAMPLES
A.	Gel	Liquid	Solid	Cheese, butter, jellies
B.	Sol	Solid	Liquid	Paints, cell fluids
C.	Aerosol	Solid	Gas	Dust, smoke
D.	Emulsion	Liquid	Liquid	Milk, hair cream

So, Hair cream is an example of a colloidal system where dispersed Phase is Liquid and dispersion Medium is also Liquid, which is the correct answer So, the correct answer is “Option D”.

Additional Information:
Properties of emulsions are:
(1) Emulsions contain a continuous phase and the dispersed phase with the boundary coming in between the phases called as ‘interface’.
(2) It has a cloudy appearance as many phase interfaces scattering light passing through the emulsions.
(3) If the emulsions are dilute, then the low wavelength and higher-frequency type of light will be scattered in more fractions and this will appear in blue in colour. This is the Tyndall effect.

Note: Emulsions are thermodynamically unstable because there is a tendency for a liquid/liquid system to separate and reduce its interfacial area and its interfacial energy. Most emulsions have kinetic stability or they are stable over a period of time.