The type of reaction that requires the addition of energy to go to completion is called an endothermic reaction.

Here's why:

* Endothermic reactions absorb heat from their surroundings. This means that the products have a higher energy content than the reactants.

* Energy input is needed to overcome the activation energy barrier and allow the reaction to proceed.

Examples of endothermic reactions:

* Melting ice: Energy is required to break the bonds holding water molecules together in a solid state.

* Photosynthesis: Plants absorb sunlight to convert carbon dioxide and water into glucose and oxygen.

* Dissolving ammonium nitrate in water: The solution becomes cold as energy is absorbed from the surroundings.

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