Which process involves a solid transforming directly into a gas?

Which process involves a solid transforming directly into a gas?

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

Answer: (D)

Solid directly becoming a gas is sublimation. This happens when a solid gains enough energy that its molecules escape into the air without first forming a liquid. A common example is dry ice, which at room temperature changes straight to carbon dioxide gas. In contrast, deposition is gas turning into a solid; condensation is gas turning into a liquid; and melting is solid turning into a liquid. Because sublimation uniquely describes a solid transforming directly into a gas, it is the correct process here.

Solid directly becoming a gas is sublimation. This happens when a solid gains enough energy that its molecules escape into the air without first forming a liquid. A common example is dry ice, which at room temperature changes straight to carbon dioxide gas. In contrast, deposition is gas turning into a solid; condensation is gas turning into a liquid; and melting is solid turning into a liquid. Because sublimation uniquely describes a solid transforming directly into a gas, it is the correct process here.