Which of the following is an example of a volatile organic compound (VOC)?

Benzene is classified as a volatile organic compound (VOC) due to its characteristics of easily vaporizing at room temperature and its significant presence in the atmosphere as a gas. VOCs are organic chemicals that have high vapor pressures and low water solubility, leading to their ability to produce vapors at ordinary temperatures. Benzene, specifically, is a well-known example of a VOC, commonly found in products like paints, solvents, and fuels.

In contrast, the other compounds listed do not fit the definition of a VOC; silicon dioxide is a stable solid and does not vaporize easily, calcium carbonate is a solid commonly found in rocks and shells, and sodium chloride (table salt) is an ionic compound that remains solid at room temperature and does not emit organic vapors. Understanding these distinctions is crucial when identifying and handling hazardous materials.