Why is boiling point called a physical property characteristic?
A physical property is any property that can be measured without actually changing what you are measuring. Boiling and melting points are physical properties because they do not change the chemical nature of the substance whose properties you are measuring. For example, if you heat water to its boiling point it turns into steam which is just water as a gas. In other words it remains water and will to return the liquid form when you cool it below its boiling point.
