A change of state that reacts when energy is endothermic is one where energy is absorbed from the surroundings. This means the system gains energy, typically in the form of heat. Here are some examples:

* Melting: Solid to liquid (ice to water)

* Boiling: Liquid to gas (water to steam)

* Sublimation: Solid to gas (dry ice to carbon dioxide gas)

Let's break it down:

* Endothermic: The process absorbs heat from the surroundings, making the surroundings cooler.

* Exothermic: The process releases heat to the surroundings, making the surroundings warmer.

Therefore, melting, boiling, and sublimation are all examples of endothermic changes of state.