Question

Smoke is a dispersion of:
A) Gas in gas
B) Gas in solid
C) Solid in gas
D) Liquid in gas

Answer 1

Hint: Smoke is a colloid. We know that colloids are defined as solutions that contain a suspension of tiny particles in them over some time. These particles in case of smoke may or may not be large enough such that they are visible to the naked eye and are referred to as pollutants.

Complete step by step solution:
Colloids can be defined as the heterogeneous mixture containing large molecules or ultramicroscopic particles of one substance being suspended in another substance. The entire mixture is referred to as the colloidal solution.
The medium in which the particles are suspended is known as the dispensed medium, and the particles that remain suspended are called the dispersed phase.
Depending upon the type of dispersed phase and dispersion medium, colloids are classified as:
Sol: Dispersed phase is solid, and the dispersion medium is liquid.
Emulsion: Both dispersed phase and dispersion medium are liquid.
Foam: Dispersed phase is gas, and the dispersion medium is liquid.
Aerosol: Dispersed medium is gas, and the dispersed phase is solid.
Thus, smoke belongs to aerosol, where the dispersion medium is gas and the dispersion phase is solid.
Therefore, smoke is a dispersion of solid in gas.

Thus, option (C) is correct.

Note: Unlike in the case of a solution, in which the solute and the solvent are inseparable, the colloidal solutions, made up of dispersed phase and dispersion medium, can be separated. In mixtures where the particles are large enough to sedimentation, the mixture is known as suspension; otherwise, the mixtures are referred to as colloidal solutions.