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

(a) Naphthalene balls disappear because they are sublimable, that is , they get directly converted into gas without coming into the liquid stage.

(b) We get the smell of perfume because of diffusion. Diffusion is the process by which a fluid goes from a place of higher concentration to lower concentration.

HOPE THIS HELPS YOU

Answer 2

$\large\red{\textbf{\underline{\underline{Here\:is\:your\:Answer :- }}}}$

(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 comprise of 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.

Hope it Helps !!