Which statement describes a chemical property of matter?
a. the density of ice is 0.4 g/ml
b. the boiling point of ethanol is 78.4c
c. rust is a flaky material with an orange-red color
d. sodium is a very reactive element that combines easily with nonmetals

D. Sodium is a very reactive element that combines easily with nonmetals

Explanation:

Chemical property is defined as the property of a substance which is observed during a reaction where the chemical composition identity of the substance gets changed.

Physical property is defined as the property which can be measured and whose value describes the state of physical system. For Example: State, density etc.

A. The density of ice is 0.4 g/ml is a physical property.

B. The boiling point of ethanol is is a physical property.

C. Rust is a flaky material with an orange-red color is a physical property.

D. Sodium is a very reactive element that combines easily with nonmetals is a chemical property.

Thus the statement that describes a chemical property of matter is  Sodium is a very reactive element that combines easily with nonmetals.