Final answer:
The chemical property among the given options is (E) 'Coal burns to form carbon dioxide,' as burning is a chemical reaction that results in a new substance. The rest are physical properties, describing aspects of the material without altering its chemical composition.
Step-by-step explanation:
Chemical Properties vs Physical Properties
In the context of your question, a chemical property represents the ability of a substance to undergo a chemical change, resulting in the formation of a new substance. In contrast, a physical property can be observed or measured without changing the composition of the material. Properties such as color, density, melting point, and electrical conductivity are considered physical because they describe the substance without altering its composition.
From the options provided, (E) 'Coal burns to form carbon dioxide' is a chemical property. This is because burning coal leads to a chemical reaction that changes the chemical composition of the coal, resulting in carbon dioxide and other compounds. The other options describe physical properties: (A) a substance's red appearance is related to the way it reflects light, (B) water's density is a measure of mass per unit volume, (C) copper's melting point is the temperature at which it transitions from solid to liquid, and (D) the electrical conductivity of iron wire is a measure of how well it allows the flow of electric charge.
For further illustration: Sulfur being yellow is a physical property, steel wool burning is a chemical property, and the weight of a gallon of milk is a physical property.