Viscosity is a measure of which property of a fluid?

• A. pH
• B. Thickness of a fluid and its resistance to flow
• C. Salt content
• D. Temperature gradient

Answer: (B)

Viscosity is about how thick a fluid is and how much its layers resist sliding past each other, i.e., its resistance to flow. The higher the viscosity, the thicker the fluid and the slower it flows. Temperature and other factors can change viscosity, but the fundamental idea is resistance to flow and thickness.

The other options don’t define viscosity: pH is a measure of acidity, salt content relates to salinity and ionic strength, and a temperature gradient describes how temperature changes over distance, not the fluid’s resistance to flow.