Give reason for the following observation:
The smell of hot sizzling food reaches us even from a considerable distance but to get the smell form cold food, we have to go close to it.
The particles of the aroma of hot cooked food mix with the particles of air spread from the kitchen, reach us and even farther away, in seconds. Due to high speed of particles and large space between them, gases show the property of diffusing very fast into other gases. Hence diffusion is the process which brings smell to us and we go close to it.