Which process is solid turning directly into gas?

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

Answer: (A)

Sublimation is the process where a solid turns directly into a gas. It happens when the particles in a solid gain enough energy to break free from the solid’s lattice and escape as a vapour, without first becoming a liquid. This is more likely at low pressures, where the liquid phase isn’t stable (below the triple point). A common example is dry ice sublimes at room temperature, turning from solid CO2 directly into CO2 gas.

Freezing is when a liquid becomes a solid as it loses energy. Condensation is the gas turning into liquid as it cools and loses energy. Deposition is the gas turning directly into a solid, skipping the liquid stage.