Question

what happens when you light an incense stick in one corner of a room

Answer 1

Solution -
When we light an incense stick in one corner of room its fragrance spreads in whole room because of the process involved DIFFUSION. It is because particles of matter are continuously moving in the air. Its parties vigourously spread and we can smell its fragrance in the whole room.

Answer 2

The particle of incense stick get diffused in air and reach our nose. Olfactory receptors in our nose receive a message from diffused particles and convey the message to brain. Thus we capture the smell of an incense stick.