Question

3. Give reason for the following observations.
(a) Naphthalene balls disappear with time without leaving
any solid.
(b) We can get the smell of perfume sitting several metres
away.​

Answer 1

Answer:

refer to the attachments............... that's my copy of 3 years ago....

Answer 2

(a) At room temperature, naphthalene balls undergo sublimation wherein they directly get converted from a solid to a gaseous state without having to undergo the intermediate state, i.e., the liquid state.

(b) Molecules of air move at a higher speed and have large intermolecular spaces. Perfumes compriseof flavoured substances that are volatile which scatters quickly in air, becoming less concentrated over a distance. Hence we are able to smell perfume sitting several metres away.