The heat required to change a unit mass of a solid substance from solid to liquid at its melting point is called

The heat required to change a unit mass of a solid substance from solid to liquid at its melting point is referred to as the latent heat of melting of solid. This specific amount of energy is needed to overcome the intermolecular forces holding the solid structure together, allowing the solid to transition into a liquid state without any change in temperature. Understanding this concept is vital in fields such as material science, thermodynamics, and various engineering applications. For instance, when ice melts to form water at 0°C, the energy input used to achieve this phase change without increasing the temperature is the latent heat of melting. Therefore, the correct answer is [C] Latent heat of melting of solid. This principle is essential for accurately calculating energy requirements in processes involving phase changes.