The melting point of a solid refers to the temperature at which it transitions from a solid to a liquid state at atmospheric pressure. It is an important characteristic of a substance, as it provides insight into the nature of the intermolecular forces of attraction present between its particles.

Option 1 states that the melting point is an indication of the strength of the intermolecular forces of attraction. This option is correct because it accurately reflects the relationship between melting point and intermolecular forces. When the intermolecular forces of attraction are strong, more energy is required to break these forces and convert the substance into a liquid. This results in a higher melting point. Conversely, a substance with weaker intermolecular forces will have a lower melting point.

Option 2 suggests that the melting point is indicative of the strength of the intermolecular forces of repulsion. However, this is incorrect as repulsive forces do not play a role in the melting process.

Option 3 states that the molecular mass of a substance is related to its melting point. While molecular mass can influence properties such as boiling point and viscosity, it is not directly related to the melting point.

Option 4 suggests that molecular size is an indication of the melting point. However, this is not accurate as molecular size alone