Which phase change occurs when a solid changes directly to a gas?

Which phase change occurs when a solid changes directly to a gas?

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

Answer: (C)

Sublimation is the phase change where a solid changes directly into a gas. This happens when the particles in the solid gain enough energy to break free from their fixed positions and enter the gas phase, skipping the liquid stage entirely. A common example is dry ice at room temperature, which goes straight from solid to carbon dioxide gas. The other options involve passing through a liquid: melting is solid to liquid, condensation is gas to liquid, and deposition is gas to solid.

Sublimation is the phase change where a solid changes directly into a gas. This happens when the particles in the solid gain enough energy to break free from their fixed positions and enter the gas phase, skipping the liquid stage entirely. A common example is dry ice at room temperature, which goes straight from solid to carbon dioxide gas.

The other options involve passing through a liquid: melting is solid to liquid, condensation is gas to liquid, and deposition is gas to solid.