Which of the following is not an example of a physical property?
a.
freezing point
c.
reactivity
b.
boiling point
d.
density

Reactivity

Explanation:

A physical property are properties that define or describe the state of matter. This includes color, temperature, density, mass etc

Chemical properties involve a change in the composition of matter. This includes, heat of combustion, enthalpy of  formation etc

Based on the given examples:

Freezing point, boiling point and density are all physical properties associated with the state of a substance. These do not involve any change in composition. In contrast, reactivity is a chemical property as the composition of matter changes during the course of a reaction.

in the analysis of systems that involve fluid flow, we frequently encounter the combination of properties u and pv.