Question

be the reason for direct conversion of solid to Vapour and vice versa is this process of physical or chemical change

Answer 1

the process called sublimation when solid changes into vapour

Answer 2

During sublimation, a solid substance when heated changes into vapour form, and the vapour on cooling gives back the substance in solid form.

During the change of state, there is no change in the composition and chemical properties of the substance. The change can be easily reversed by changing temperature. There sublimation can also be said as a physical change.