Correct Option
The correct option is (c) 1 and 3 only.
Explanation
The melting point is a characteristic physical property of solids. It represents the temperature at which the solid and liquid phases of a substance are in equilibrium at a specified pressure. This temperature reflects the thermal energy required to overcome the intermolecular forces holding the solid lattice together.
Statement-wise Analysis
- Statement 1 is Correct: The melting point is defined as the specific temperature at which a solid substance transitions into a liquid state at atmospheric pressure. At this temperature, the solid and liquid phases coexist in equilibrium.
- Statement 2 is Incorrect: The melting point is directly proportional to the strength of the forces of attraction between the constituent particles (atoms, ions, or molecules). A higher melting point indicates that a large amount of energy is required to break the inter-particle bonds, implying stronger forces of attraction, not weaker ones.
- Statement 3 is Correct: The melting point of pure ice at standard atmospheric pressure is 0°C. On the Kelvin scale, this corresponds to 273.15 K ($0 + 273.15$).
Key Takeaway: The melting point of a solid is a measure of the strength of the intermolecular forces of attraction; higher melting points signify stronger forces holding the particles together.