Sublimation is the phase change from which to which?

• A. Gas to liquid
• B. Solid to gas
• C. Liquid to gas
• D. Solid to liquid

Answer: (B)

Sublimation is the phase change from solid directly to gas, bypassing the liquid stage. This happens when a solid gains enough energy for its particles to overcome intermolecular forces and escape into the vapor phase without becoming liquid first. It occurs at conditions where the solid has a noticeable vapor pressure compared to the surrounding environment, such as dry ice turning into CO2 gas at room temperature. In a phase diagram, sublimation occurs along the boundary between the solid and gas, usually above the triple point. The process is endothermic, requiring heat to be added to drive it.

The other transitions are different: gas to liquid is condensation, solid to liquid is melting, and liquid to gas is vaporization or boiling.