What does sublimation refer to in a chemical process?

Sublimation is defined as the process in which a substance transitions directly from a solid state to a gaseous state without passing through the liquid phase. This phenomenon occurs under specific conditions, typically when the temperature and pressure are such that the solid does not become a liquid before turning into gas. Examples of sublimation can be seen in substances like dry ice (solid carbon dioxide) and iodine, which transition directly from solid to gas when exposed to certain temperatures.

This process is significant in various applications, including freeze-drying and in certain chemical analysis methods. The other options provide descriptions of different state transitions: from liquid to gas, gas to liquid, and solid to liquid, but none accurately define sublimation.