Final answer:
The boiling point is the physical property of matter represented by a liquid at 660 degrees Celsius.
Step-by-step explanation:
The physical property of matter that is represented by a liquid at 660 degrees Celsius is the boiling point. The boiling point is the temperature at which a liquid changes into a gas. It is important to note that the boiling point of a substance depends on the pressure. In this case, the question does not specify the pressure, so we cannot determine the boiling point of the liquid at 660 degrees Celsius.