the factors affecting melting point.1. External PRESSURE: Normal solids, e.g. iron, copper and wax, expand when they change into liquids. When pressure is applied on the surface of a normal solid, expansion is suppressed and melting is delay. Thus, the melting point of a normal solid is raised. Solids, like ice and bismuth, contract on melting into liquids. When pressure is applied on the surface of such a solid, the change into the LIQUID is assisted. Thus, the melting point of ice is lowered by the application of pressure.2. Presence of H-bonding: The intermolecular hydrogen bonding (in water, ammonia etc) and The intramolecular hydrogen bonding (in Salicylic acid, o-nitrophenol etc) KEEPS the molecules CLOSER due to dipole –dipole intermolecular force.3. Type of bonds present in molecules: Ionic bonds are stronger than covalent bonds so materials with ionic bonds will have higher melting point.4. Presence of other substance: Presence of ice or lipid CHANGES the melting point of water or presence of Urea in Benzene.