Question

Give reason for the following observation :

The smell of hot sizzling food reaches us even from a considerable distance but to get the smell from cold food, we have to go close to it.

Answer 1

The aroma of hot, sizzling food reaches us very easily even when we are far away from it, but  the aroma of cold food reaches us only when we are near it because the rate of diffusion of a hot gas is faster than cold gas. When the gas is hot, the particles have greater kinetic energy and they move faster; therefore, they have a higher rate of diffusion.