Which change involves a gas turning directly to a solid without becoming a liquid?

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

Answer: (D)

Gas turning directly into a solid without becoming a liquid is called deposition (desublimation). This happens when gas molecules lose enough energy to lock directly into a solid structure, usually at low temperatures and/or low pressures. A familiar example is frost forming on a cold surface, where water vapor deposits as ice crystals instead of condensing into liquid water first. The other transitions involve a liquid step: condensation is gas to liquid, freezing is liquid to solid, and vaporization is liquid to gas. Deposition is the direct gas-to-solid change, so it’s the correct choice.