Question

Why it is that to smell old food ,we have to go close but smell of hot food reaclus us several away?

Answer 1

It's because of diffusion. Old food particles have less kinetic energy so you have to go near it but it is vice versa in hot foods

Answer 2

When molecules of some volatile substances from hot sizzling food diffuse into air and reach the odur sensitive part of our nose we have the perception of smell.

At higher temperature of molecules diffuse into air at a faster rate and therefore travel long distances.

Hence the smell of hot sizzling food reaches as quickly even when we are several metres away.

While on the contrary , when the food is called the vapour diffuse is at a slower rate and therefore does not travel longer distances.

So, one has to come closer to have the perception of smell.