AI-generated practice question — model-generated for extra practice, not a previous-year CBSE board question.
In decomposition reactions, energy is absorbed to break a single substance into two or more products. Since energy is absorbed (not released), they are called endothermic reactions.
The key link is: decomposition = breaking down of one substance → requires energy input → energy absorbed = endothermic. Examiners want both the definition of endothermic (energy absorbed) and its connection to decomposition in one line.