Ametal melts at 450 degrees celsius is this physical or chemical property

Melting point is a physical property.

A physical property of a substance is anything about the substance that can be observed or measured without changing the identity or composition (chemical nature) of the substance.

The  observation will usually consist of some kind of numerical measurement although non-numerical observations descriptions can sometimes also be a physical property.

Examples of physical properties are melting point, freezing point, color, texture, solubility, odor, thermal conductivity, density, ductility, malleability , brittleness, electrical conductivity and hardness

the answer is 75.0%.