Question

• Put an unlit incense stick in a corner of your class. How close do you have to go near it so as to get its smell?
• Now light the incense stick. What happens? Do you get the smell sitting at a distance?
• Record your observations.

NCERT Class 9th Science Ch 1 Matter in Our Surroundings

Answer 1

When we take the smell of the unlit incense stick, we have to go very close to it. But when we light it and place it in the corner of the room, its smell spreads everywhere in the room and we no longer have to go near it to take smell. This is because the particles of the incense stick are mising up with air and as we know that the gaseous molecules move faster, thus, the smell spreads every where within seconds. 

Answer 2

When we light the incense stick ,the sent in the vapour form and mixes with the air and moves across the room and reach our nose.