Chlorine gas will support which of the following?

Chlorine gas is a highly reactive element, and its role related to combustion is significant. When considering combustion, we typically think of a reaction that requires a fuel and an oxidizer. Chlorine, despite being a toxic gas, can act as a powerful oxidizing agent. In the presence of a combustible substance—such as organic materials or gases—chlorine can support combustion by supplying the necessary oxygen needed for the fuel to ignite and burn.

This characteristic makes chlorine particularly important in various chemical processes, including disinfection and oxidation reactions. While it can participate in reactions that produce energy, its oxidizing properties help facilitate and sustain combustion reactions involving suitable fuels.

The other choices, while they might relate to chlorine in different contexts, do not properly characterize its primary role in combustion. Dense fog formation might involve different atmospheric conditions, and while water vapor can be present in many chemical reactions, it doesn’t pertain to the supporting role of chlorine in combustion. Similarly, while chlorine can lead to corrosion of metals under certain conditions, this corrosion is more a consequence of chemical reactivity rather than an indication of supporting combustion. Thus, the association of chlorine gas with supporting combustion stands out as the most fitting response.