The correct option is (c).
Explanation
Melting is a physical process that results in the phase transition of a substance from a solid to a liquid. This occurs when the internal energy of the solid increases, typically through the application of heat or pressure, to a specific temperature known as the melting point.Statement-wise Analysis:
- Statement 1 is Incorrect. The temperature at which a solid melts to become a liquid at atmospheric pressure is called its melting point. The boiling point is the temperature at which a liquid changes into a gas or vapor.
- Statement 2 is Correct. The melting point of a solid is a direct measure of the strength of the force of attraction between its constituent particles. Solids with stronger intermolecular forces (such as ionic bonds or metallic bonds) require more energy to break the lattice structure, resulting in a higher melting point. Conversely, solids with weak forces (like Van der Waals forces) have lower melting points.
- Statement 3 is Correct. During the process of melting, the temperature of the system remains constant once the melting point is reached, provided the pressure is constant. The heat energy supplied during this phase is absorbed to overcome the forces of attraction between the particles to change the state from solid to liquid, rather than increasing the kinetic energy (temperature) of the particles. This absorbed energy is known as the Latent Heat of Fusion.
Key Takeaway: The melting point indicates the strength of intermolecular forces in a solid. During phase transitions (melting or boiling), the temperature of a substance remains constant due to the absorption of latent heat.