Question

Give reasons for the following observations :-

a) Napthalene balls disappear with time without leaving and solid .

b) We can get the smell of perfume sitting several meters away .

$\huge\mathcal{\fcolorbox{lime}{black}{\orange{@AshuBhaiya4eva}}}$​

Answer 1

Answer:

1.Naphthalene balls disappear with time without leaving any solid, because naphthalene balls sublime and directly changes into vapour state without leaving any solid.

2.When perfume is released from the bottle it quickly changes into a vapor. The perfume vapor moves rapidly in all directions as it is volatile. The kinetic energy of the gas molecules is high and the rate of diffusion is high. Hence, we can get the smell of perfume sitting several meters away.

Answer 2

Answer:

a) Naphthalene balls disappear with time without leaving any solid, because naphthalene balls sublime and directly changes into vapour state without leaving any solid.

or

Naphthalene undergoes sublimation easily i.e., the change of state of naphthalene from solid to gas without the intervention of the liquid state. Thus, naphthalene balls keep on forming naphthalene vapours which disappear into the air with time without leaving any solid

b) When perfume is released it quickly changes into vapour. The kinetic energy of gas molecules is high & the rate of diffusion is high. Hence we can smell the perfume sitting several metres away.

hope this will help you