Question

How do we detect the smell of an agar batti (incense stick)?

Answer 1

The smoke given out by an incense stick is gas. A gas consists of particles tending to move away from each other. Their interparticle force of attraction is almost negligible and they have abundant free spaces between them.Thus,when it is burned in one end of the room,the fragrance spreads to the other end of room.  

Answer 2

Because the incense stick when lighting it emits gas in the form of smoke and since gases contains high amount of kinetic energy so the molecules move very faster due to the high amount of kinetic energy and therefore we get the smell of it