Physical properties of wastewater are those which can usually be detected by ______.

• A. Instruments
• B. Human senses
• C. Calculations
• D. Laboratory tests

Answer: (B)

Physical properties are observations you can detect with your senses—how wastewater looks, smells, or feels. Color and odor are classic examples, and temperature is something you can sense by touch. These attributes reflect the physical state rather than chemical makeup, so they’re described as physical properties. Instruments or laboratory tests go beyond what the senses can detect, and calculations aren’t properties themselves. So detecting with human senses is the defining way to identify these physical properties.