(a) When an incense stick(agarbatti) is lighted in one corner of a room, its fragrance quickly spreads in the entire room. Name the process involved in this.

(b) A girl is cooking some food in the kitchen. The smell of food being cooked soon reaches her brother’s room. Explain how the smell could have reached her brother’s room.

(a) When an incense stick is burnt, the incense present in it vaporizes because of heat. The vapours move rapidly in all directions due to the diffusion. The vapour mixes with air and reaches to us. In similar way we sense the good or bad smell from a distance.

(b) The particles of the aroma of hot cooked food mix with the particles of air spread from the kitchen, reach us and even farther away, in seconds. Due to high speed of particles and large space between them, gases show the property of diffusing very fast into other gases. Hence diffusion is the process which brings smell to brother’s room.


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