The process in which a substance changes from solid to gas is called sublimation.

Here's a breakdown:

* Solid: In a solid, molecules are closely packed together and have a fixed shape and volume.

* Gas: In a gas, molecules are widely spaced and move freely, taking the shape and volume of their container.

Sublimation bypasses the liquid state entirely, meaning the substance doesn't melt first. Examples of sublimation include:

* Dry ice (solid carbon dioxide) turning into carbon dioxide gas.

* Snow or ice disappearing on a cold, windy day.

* Mothballs gradually disappearing.

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