Question

when we light an incense stick in a corner of our room why does it fragrance spread in the whole room very quickly

Answer 1

Because it's intermolecular space is more and it move faster in gas state

Answer 2

because the particles of matter continuously moving. On this basis we can say that when we light the incense stick it will convert into gaseous state and in gas particles are moving so fast as their fragrance used spread in the whole room quickly.

Now I hope you understand.