Question

Gas fills the vessel in which ice
kept give reason

Answer 1

actually the molecules in the gas are very much far apart from each other and the intermolecular forces of attraction between them is too weak and hence when u place any gas inside any closed chamber then the molecules will try to fill up the space as there intermolecular forces is negligible.

Answer 2

When certain solids are heated, their molecules gain a lot of kinetic energy quickly and move so fast that they break away from their fixed positions and escape straight to the surrounding as gas .