Which change of state involves a solid becoming a gas without becoming a liquid first?

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

Answer: (B)

Sublimation is the process where a solid transitions directly into a gas without passing through the liquid phase. This change of state occurs under specific conditions, such as low pressure or high temperature, and is characteristic of certain substances, like dry ice (solid carbon dioxide), which sublimates at normal atmospheric pressure. This process is notable because it is the opposite of deposition, where a gas transforms directly into a solid. Understanding sublimation is essential in various applications, including refrigeration and the preservation of biological samples, where maintaining material integrity during phase changes is crucial.