Question

Give reasons; a) A sponge can be pressed easily still it is called a solid. b) Water vapours have more kinetic energy than water at the same temperature c) Naphthalene balls disappear with time without leaving any solid.

Answer 1

1. sponge can be pressed but it is considered as solid because sponge has minute holes in which air is trapped, when we press it the air is expelled out and we are able to compress.

2. water vapours more energy in the form of latent heat of vaporisation that's why they have more kinetic energy.

3. naphthalene balls disappear because they are sublimiable substance converts directly from solid to gas .

Answer 2

i) A sponge can be pressed easily still it is called a solid

A sponge can be compressed easily, but it can be considered as a solid. Because the sponge has lots of minute holes that is filled up with air. When we compress sponge, the air is expelled out.

ii) water vapours have more energy than water at the same temperature.

When water converts into water vapour it absorbs the latent heat of vaporisation. But water in the liquid state does not contain the latent heat of vaporization. Hence water vapour has more energy in the form of latent heat than water at the same temperature.