What is the immediate change of a solid into a vapor called?

The immediate change of a solid into a vapor is known as sublimation. This process occurs when the molecules in a solid gain enough energy to transition directly into the gas phase, bypassing the liquid phase entirely. A common example of sublimation is dry ice (solid carbon dioxide), which vaporizes without melting into a liquid state at atmospheric pressure. This phenomenon is significant in various scientific and industrial applications, including freeze-drying and purification processes.

Evaporation refers to the transition of liquid into vapor, condensation is the change of vapor back to liquid, and melting is the process of a solid turning into a liquid when heat is applied. These terms refer to different phase changes and are not applicable in the context of a solid converting directly to vapor. Hence, sublimation is the correct choice as it explicitly describes the transition from solid to gas.