Which process is the reverse of sublimation, where a gas turns directly into a solid?

Which process is the reverse of sublimation, where a gas turns directly into a solid?

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

Answer: (A)

Phase changes involve transitions between states of matter with energy changes. Sublimation is solid turning into gas when heat is added. The reverse occurs when a gas loses energy and becomes a solid directly, without forming a liquid—that process is deposition (also called desublimation). A common example is frost forming on cold surfaces from water vapor turning directly into solid ice. The other terms describe different transitions: condensation is gas turning into liquid, and freezing is liquid turning into solid. So deposition is the process where a gas turns directly into a solid.

Phase changes involve transitions between states of matter with energy changes. Sublimation is solid turning into gas when heat is added. The reverse occurs when a gas loses energy and becomes a solid directly, without forming a liquid—that process is deposition (also called desublimation). A common example is frost forming on cold surfaces from water vapor turning directly into solid ice. The other terms describe different transitions: condensation is gas turning into liquid, and freezing is liquid turning into solid. So deposition is the process where a gas turns directly into a solid.