Name the four broad categories of water quality. Physical, ______, biological, radiological.

• A. Thermal
• B. Gaseous
• C. Chemical
• D. Biochemical

Answer: (C)

The missing category is chemical. In water quality, contaminants are commonly grouped into physical, chemical, biological, and radiological. The chemical category covers dissolved and suspended substances such as minerals, metals, salts, nutrients, pesticides, and organic compounds. These are identified and treated through chemical analyses and processes, distinguishing them from physical factors like turbidity or color, biological concerns like pathogens and algae, and radiological substances like radioactive materials. The other options aren’t standard broad categories: gaseous and biochemical aren’t used as primary groupings, and thermal relates to physical properties like temperature rather than forming a separate category.