(a)
The process of conversion of gas into liquid form is called condensation.
[1 Mark]
(b)
The process of conversion of liquid to solid at the melting/freezing point is termed as freezing.
[1 Mark]
(c)
The process of conversion of matter from a liquid state into a gas state is called vaporisation.
If the vaporisation is occurring at boiling point, it is called boiling.