What describes chlorine?

Chlorine is best described as a fairly reactive, poisonous dense green gas. This characterization is accurate because chlorine exists as a diatomic molecule (Cl2) and is known for its reactivity, particularly with metals and nonmetals, forming various compounds such as chlorides. Its greenish-yellow color and pungent odor, along with its toxic nature, further support this description. Chlorine is commonly utilized in water treatment and sanitation due to its strong disinfecting properties.

In contrast, other options do not correctly depict the properties of chlorine. For instance, while some gases may be non-reactive, chlorine’s reactivity is one of its key characteristics. Additionally, chlorine is not a volatile red liquid; it does not have the physical state of a solid at room temperature, as it exists in gaseous form under standard conditions.