Question

Give reason for the following observations .
a. Naphthalene balls disappear with time without leaving any solid.
b. We can get the smell perfume sitting several meters away .
c. A gas fills completely the vessels in which it is kept .

Answer 1

a and b because solid directly changes into vapor called sublimation I guess
and c. The process of diffusion takes place

Answer 2

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(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 !!