Final answer:
b) Melting materials means a solid is becoming a liquid at high temperatures, occurring at the melting point which is unique for each substance. This process is endothermic, involving the absorption of heat to overcome intermolecular forces.
Step-by-step explanation:
When discussing melting materials, the term refers to the process of a solid becoming a liquid. This transition happens when the solid reaches its melting point, which is the temperature at which it changes phase to become liquid.
There are different processes described, but what melting really involves is mixing the materials at high temperatures, which correctly corresponds to option b).
During melting, heat is absorbed, and this is known as an endothermic process. At this point, the temperature of the substance does not increase; instead, the added heat causes the particles in the solid to overcome the attractive forces holding them together.
This leads to a change in the structure from an ordered pattern to a more disorganized one as the solid melts into a liquid. The amount of heat required for this transition is unique to each substance and is termed the enthalpy of fusion.