Final answer:
Heat energy is absorbed during the phase change of melting, where a solid turns into a liquid, making melting an endothermic process requiring heat.
Step-by-step explanation:
Heat energy is absorbed during the process of melting. When a solid turns into a liquid, this phase change is an endothermic process, meaning that it requires the addition of heat. The heat that is absorbed causes the molecules in the solid to move more vigorously, breaking the intermolecular forces that hold them together in the solid state. Therefore, the correct answer to the question of when heat energy is absorbed is B. Melting.
Other endothermic processes where heat is absorbed include evaporation and sublimation. The heat required for these phase changes is referred to as the latent heat or the enthalpy of transformation, such as the enthalpy of fusion for melting, and the enthalpy of vaporization for evaporation.