Question

Smoke is an example of?
A. gas dispersed in liquid.
B. gas dispersed in solid.
C. solid dispersed in gas.
D. solid dispersed in liquid.

Answer 1

Hint: The smoke, dust are the type 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 its 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:

DISPERSED PHASE	DISPERSION MEDIUM	TYPE OF COLLOIDS	EXAMPLES
Gas	Liquid	Foam	Whipped cream
Gas	Solid	Solid Sol	Foam rubber
Solid	Gas	Aerosol	Dust, smoke
Solid	Liquid	Sol	Paints

Smoke is an example of a colloidal system where dispersed Phase is Solid and dispersion Medium is Gas, which is the correct answer and the option which matches is C.
So, the correct answer is option (C).

Additional Information:
Applications of colloids:
(1) The impurities present in natural water are removed by adding alum which coagulates them.
(2) In the manufacture of inks and paints, colloids are used. In ball-point pens, the inks are used as gel.
(3) Colloids are used as thickening agents in industrial products as lotions, coatings.
Examples of colloids:
(1) Seawater is blue because of the presence of colloidal impurities in it, which scatter blue light.
(2) Various dairy products are colloidal in nature; the dairy products are cake, milk, bread.

Note: Do not get confused between the Solid sol and aerosol. Smoke is an example of aerosol where dispersed Phase is Solid and dispersion Medium is gas. Under solid sol, the dispersed phase is gas and the dispersion medium is solid, its example is foam rubber.