Question

An example of solid-solid system is:
(a) Smoke
(b) Coke
(c) Synthetic gems
(d) Pumice stone

Answer 1

Hint: Attempt this question by keeping in mind the properties of colloids and its classification. Also remember that the type of colloid is decided by its dispersion phase and medium.

Complete step by step answer:
IUPAC defines colloidal state as, “The colloidal state is the state of subdivision in which molecules or polymolecular particles having at least one dimension in the range of 1 nanometre and 1 micrometre, are dispersed in some medium “.
Colloidal system is also known as colloidal dispersion, colloidal suspension. It is an “intimate mixture of two substances, one of which, called the dispersed phase (or colloid), is uniformly distributed in a finely divided state through the second substance, called the dispersion medium (or dispersing medium). Colloid Particles range from 1 to 1000 nm in diameter and they remain suspended in the solution”.
Colloids can be classified as –

Medium/phase	Dispersed Phase
	Gas	Liquid	Solid
Dispersion Medium	Gas	No colloid	aerosol	Solid aerosol
	Liquid	Foam	Emulsion	Sol
	Solid	Solid foam	Gel	Solid sol

From the given options –
• Smoke – solid in gas
• Coke – gas in liquid
• Pumice stone – gas in solid
• Synthetic gems – solid in solid
Since both dispersed phase and dispersed medium are solid in case of synthetic gems.
Therefore, the answer is option – (c).

Note: Do not confuse between dispersed phase and dispersed medium. The substance dispersed in the solution is the dispersed phase, and the solution in which it is dispersed is called dispersion medium.