Which of the following describes a chemical property? a. The density of iron is \(7.87 \mathrm{~g} / \mathrm{cm}^{3}\). b. A platinum wire glows red when heated. c. An iron bar rusts. d. Aluminum is a silver-colored metal.

Firstly, let's go through each of the options and comprehend their nature as a property: a. The density of iron is 7.87 g/cm³ - This is a physical property as it can be observed without a chemical reaction taking place. Density represents mass per unit volume. b. A platinum wire glows red when heated - This is a physical property since the glowing red wire doesn't involve a chemical reaction or change in the composition of platinum. c. An iron bar rusts - This involves a chemical reaction as the iron reacts with oxygen and moisture to form rust. This process alters the chemical composition of the iron. d. Aluminum is a silver-colored metal - This is a physical property, expressing the color and appearance of aluminum without involving any chemical reaction or alteration in its composition.

From the given choices, we can clearly identify that only choice 'c' involves a chemical reaction and describes how the substance interacts with other substances (oxygen and moisture): c. An iron bar rusts So, the correct answer is option \(c\).