Question

Smoke is a colloid of:

• A. Solid in solid
• B. Liquid in solid
• C. Solid in liquid
• D. Solid in gas

Hint:

In smoke, small solid particles are suspended in the air, which is why it is classified as a solid in gas colloid.

Answer 1

The Correct Option is D

Compare smoke with fog and with ordinary dust floating in a sunbeam.

1. Solid in solid: that pairing fits something dense like an alloy, nothing like the drifting haze of smoke rising from a fire.
2. Liquid in solid: that pairing fits something like cheese, holding trapped liquid, unrelated to smoke's dry, drifting particles.
3. Solid in liquid: that pairing fits muddy water, with solid particles floating in liquid, not particles floating through open air.
4. Solid in gas: dust floating in a sunbeam is solid particles carried by air, and smoke behaves the same way, tiny solid soot particles carried and dispersed by the surrounding air.

Since smoke behaves like dust drifting through air, solid particles carried by a gas, the correct answer is solid in gas.

Answer 2

Identify the state of smoke's surrounding medium and the state of the particles carried within it.

1. Solid in solid: here the surrounding medium would need to be solid, but smoke drifts and spreads freely, which a solid medium would not allow.
2. Liquid in solid: here the medium would need to be solid too, which does not match smoke's free-flowing, airborne behavior.
3. Solid in liquid: here the medium would need to be liquid, but smoke rises and spreads through open air, not through a liquid.
4. Solid in gas: smoke's medium is air, a gas, and the particles carried within it are solid soot and ash, matching this pairing on both counts.

Since smoke's medium is a gas carrying solid particles, the correct answer is solid in gas.