(i) Boiling point of a liquid is the temperature at which it starts boiling at one atmospheric pressure.
(ii) Water boils at 373K
(iii) Heat supplied to water when it changes state is hidden, i.e., during this change of state temperature does not rise though heat is given.This is called latent heat of vaporisation.

Boiling point of a liquid increases with pressure.Because b. pt. is the temperature at which the pressure of the liquid becomes equal to the atmospheric pressure.Thus if the atmospheric pressure is increased, more heat will have to be given to make it equal to the existing pressure.Thus b. pt. increases with the pressure above the liquid.

At a given pressure, reduction of temperature liquefies a gas at some point.At a given temperature, increase of pressure also results in liquefying a gas.But here the essential condition is that the temperature has to be below a certain value called critical temperature.

Since ghee freezes at room temperature but mustard oil does not, it shows that intermolecular forces between particles of ghee are stronger compared to those of mustard oil.Higher the intermolecular forces, higher is the melting point.Therefore, ghee has a higher melting point than that of mustard oil.

Energy equivalent to latent heat of solidification is released when 1 kg of water solidifies into ice.Thus ice has a lower energy than that of water.

(i) Compressibility : wood
(ii) Particle motion : wood
(iii) Rigidity: air

Ice: It is rigid and has definite shape.It can be stored without a container.
Water: It is fluid and has no definite shape.It cannot be stored without a container.

Intermolecular force of attraction between particles of a matter makes it a solid, a liquid or a gas.High intermolecular force of attraction results in closely packed particles which makes a solid.Weaker intermolecular force of attraction means particles are less compactly packed which makes a liquid.Almost no intermolecular force of attraction allows the particles to move randomly giving a gas.