The process of a solid changing directly into gas is called sublimation.

Here's a breakdown:

* Solid: A state of matter with a fixed shape and volume.

* Gas: A state of matter with no fixed shape or volume.

* Sublimation: The transition of a substance directly from the solid to the gaseous state without passing through the liquid state.

Examples of sublimation:

* Dry ice (solid carbon dioxide) sublimes into carbon dioxide gas at room temperature.

* Mothballs are made of substances that sublime over time, which helps repel moths.

* Freeze-dried foods are prepared by freezing the food and then sublimating the ice, leaving behind a lightweight, dehydrated product.