Which process describes a solid turning directly into a gas?

Which process describes a solid turning directly into a gas?

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

Answer: (C)

Phase changes among solid, liquid, and gas are all about how energy moves to overcome intermolecular forces. Sublimation is the process where a solid becomes a gas directly, skipping the liquid stage. This happens when the particles at the surface gain enough energy to break away into the vapor phase, often under low pressure or for substances with high vapor pressure at that temperature. A classic example is dry ice, which goes from solid to carbon dioxide gas at room temperature. The other processes involve a liquid in between or opposite directions: deposition is gas turning into a solid, melting is solid turning into a liquid, and condensation is gas turning into a liquid.

Phase changes among solid, liquid, and gas are all about how energy moves to overcome intermolecular forces. Sublimation is the process where a solid becomes a gas directly, skipping the liquid stage. This happens when the particles at the surface gain enough energy to break away into the vapor phase, often under low pressure or for substances with high vapor pressure at that temperature. A classic example is dry ice, which goes from solid to carbon dioxide gas at room temperature. The other processes involve a liquid in between or opposite directions: deposition is gas turning into a solid, melting is solid turning into a liquid, and condensation is gas turning into a liquid.