Which process is direct solid to gas?

Which process is direct solid to gas?

• A. Deposition
• B. Melting
• C. Sublimation
• D. Freezing

Answer: (C)

Direct solid to gas is sublimation. This occurs when a solid gains enough energy for its molecules to escape directly into the vapor phase, bypassing the liquid state. Sublimation happens for substances with significant vapor pressure at relatively low temperatures or under reduced pressure—for example, dry ice (solid carbon dioxide) at room temperature slowly turning into gas. By contrast, deposition is gas turning into a solid, melting is solid turning into liquid, and freezing is liquid turning into a solid. So the solid-to-gas transformation is the sublimation process.

Direct solid to gas is sublimation. This occurs when a solid gains enough energy for its molecules to escape directly into the vapor phase, bypassing the liquid state. Sublimation happens for substances with significant vapor pressure at relatively low temperatures or under reduced pressure—for example, dry ice (solid carbon dioxide) at room temperature slowly turning into gas. By contrast, deposition is gas turning into a solid, melting is solid turning into liquid, and freezing is liquid turning into a solid. So the solid-to-gas transformation is the sublimation process.