The correct option is (c).
Explanation
Smoke is a collection of airborne solid and liquid particulates and gases emitted when a material undergoes combustion or pyrolysis. It is technically classified as an aerosol, specifically a solid dispersed in a gas.
- Statement 1 is Correct: Smoke contains a mixture of gases (such as carbon dioxide, carbon monoxide, and nitrogen oxides) and fine solid particles (particulate matter like soot, ash, and unburnt carbon).
- Statement 2 is Incorrect: Smoke is not composed entirely of water vapour. While water vapour is often a byproduct of combustion, smoke is characterized by the presence of particulate matter and combustion gases. A visible mass composed entirely of condensed water vapour is referred to as steam, mist, or fog.
- Statement 3 is Correct: Smoke is produced by the burning of fuels (such as wood, coal, petroleum, or biomass). The density and composition of the smoke depend on the nature of the fuel and the efficiency of combustion (complete vs. incomplete).
Key Takeaway: Smoke is a complex mixture of gases and fine solid particles resulting from combustion, distinct from water vapour which forms steam or clouds.