Question

Gas changes into solid without changing into liquid state how

Answer 1

Deposition is a thermodynamic process, a phase transition in which gas transforms into solid.
 

The reverse of deposition is sublimation.

Answer 2

Gas changes into solid or solid change into vapours it is due sublimation.It is the process in which solid directly change into vapour on heating and of change into solid on cooling.Eg naphthalene,dry ice (solid carbon dioxide)etc........May be it will help you......