Which of the following is an example of an endothermic reaction?

An endothermic reaction is characterized by the absorption of heat from the surroundings, resulting in a decrease in the temperature of the immediate environment. In this context, melting an ice cube is indeed an endothermic process. When an ice cube melts, it requires heat energy to break the hydrogen bonds that hold the water molecules tightly together in their solid state. This heat is absorbed from the environment, which is why the area around the melting ice cube can feel colder.

In contrast, the freezing of water is an exothermic reaction because it releases heat as the water transitions from liquid to solid. The burning of a candle involves combustion, which is an exothermic reaction that releases energy in the form of heat and light. Washing hair generally requires heat from water but does not fit the definition of an endothermic reaction in this chemical context. Thus, melting an ice cube is a clear example of an endothermic reaction due to its heat-absorbing nature.