Which substances are characterized as oxidizable and may include Fe2+, H2S, or Mn2+?

The correct answer is the classification of substances as dissolved oxidizable molecules. This term specifically refers to substances that can undergo oxidation reactions, meaning they can lose electrons and therefore interact with oxidizing agents in the water.

In the context of the specific examples given—Fe2+ (ferrous ion), H2S (hydrogen sulfide), and Mn2+ (manganese ion)—all of these compounds are indeed capable of being oxidized, which aligns perfectly with the definition of oxidizable substances. For instance, Fe2+ can be oxidized to Fe3+, H2S can be oxidized to elemental sulfur or sulfate, and Mn2+ can be oxidized to MnO2 or manganese oxides.

Other options, like chemical contaminants, solid particulates, and organic compounds, while they may contain oxidizable components, do not directly describe substances primarily characterized by their ability to be oxidized in the water treatment process. Chemical contaminants is a broad category that includes various unwanted substances in water, solid particulates refer to physical debris or particles suspended in liquids, and organic compounds can be oxidizable, but they are not limited to just dissolved forms, encompassing a wider range of materials. Thus, dissolved oxidizable molecules are the precise