Deposition is the change from which state to which?

• A. Gas to Solid
• B. Solid to Gas
• C. Liquid to Solid
• D. Gas to Liquid

Answer: (A)

Deposition is a phase change where a gas becomes a solid. It happens when gas molecules lose enough energy to stop moving freely and settle into a fixed, solid arrangement, often on a surface. Energy is released in this process, so it is exothermic. A common example is frost forming from water vapor on a cold surface, directly turning into ice. This is the reverse of sublimation, which is solid turning into a gas. The other transitions involve going through the liquid stage or require energy input: solid to gas is sublimation, liquid to solid is freezing, and gas to liquid is condensation. So the gas-to-solid path is deposition.