Which of the following is considered a physical characteristic of water?

Turbidity is recognized as a physical characteristic of water because it pertains to the clarity of the water, which is influenced by the presence of suspended solids, such as silt, clay, and organic matter. These particles scatter light, leading to a decrease in water clarity and an increase in turbidity levels. The measurement of turbidity provides insight into the visual quality of water and can indicate levels of pollution or sedimentation.

In contrast, pH, conductivity, and alkalinity are considered chemical characteristics. pH measures the acidity or basicity of water, conductivity assesses the water's ability to conduct electricity, which is usually influenced by ion concentration, and alkalinity refers to the water's capacity to neutralize acids. Each of these parameters provides detailed information about the chemical composition and behavior of water, but they do not classify it in terms of its physical appearance or particulate matter, which is the essence of turbidity as a physical characteristic.