What is the process in which a solid becomes a gas?

What is the process in which a solid becomes a gas?

• A. Condensation
• B. Sublimation
• C. Evaporation
• D. Precipitation

Answer: (B)

The process being tested is solid turning directly into a gas, bypassing the liquid phase. This is sublimation, which happens when solid molecules gain enough energy to break free from the solid’s structure and enter the gas state. It tends to occur under conditions of low pressure or with heat applied. A familiar example is dry ice, which sublimes at room temperature to become carbon dioxide gas. By contrast, evaporation is liquid to gas, condensation is gas to liquid, and precipitation is a solid forming from a solution or from vapor—not a solid-to-gas change.

The process being tested is solid turning directly into a gas, bypassing the liquid phase. This is sublimation, which happens when solid molecules gain enough energy to break free from the solid’s structure and enter the gas state. It tends to occur under conditions of low pressure or with heat applied. A familiar example is dry ice, which sublimes at room temperature to become carbon dioxide gas.

By contrast, evaporation is liquid to gas, condensation is gas to liquid, and precipitation is a solid forming from a solution or from vapor—not a solid-to-gas change.