Which of the following is a chemical property of the noble gases? a. the boiling points are close together. b. the melting points are close together. c. they are unreactive. d. mass increases down the group.

Option (C) is the correct answer.

Explanation:

Chemical property is defined as the property that causes a change in chemical composition of a substance.

For example, toxicity, reactivity, combustibility etc are chemical properties.

Physical property is defined as the property that causes no change in chemical composition of a substance.

For example, melting point, boiling point, mass, volume etc are physical properties.

Therefore, we can conclude that they are unreactive is a chemical property of the noble gases.