Conversion of gas to liquid is called as :
Sublimation- Itis the transition of a substance directly from the solid to the gas phase without passing through the intermediate liquid phase. Sublimation is an endothermic phase transition that occurs at temperatures and pressures below a substance's triple point in its phase diagram.
Condensation- It is the change of the physical state of matter from gas phase into liquid phase
Evaporation is a type of vaporization of a liquid that occurs from the surface of a liquid into a gaseous phase that is not saturated with the evaporating substance.
Deposition is a thermodynamic process, a phase transition in which gas transforms into solid.
Melting (also known as fusion) is a physical process that results in the phase transition of a substance from a solid to a liquid. This occurs when the internal energy of the solid increases, typically by the application of heat or pressure, which increases the substance's temperature to the melting point.