Answer: lowers its surface tension.
- A leaves it unchanged
- B raises its surface tension
- C lowers its surface tension
- D raises its density sharply
Correct answer: C. lowers its surface tension
Explanation: Surfactants reduce surface tension, which improves wetting and cleaning action.
Since the same volume of fluid must pass every cross-section per second (continuity), the fluid speeds up where the pipe narrows; Bernoulli's equation then says this faster-moving fluid has lower pressure - the principle behind a venturi meter and an aircraft wing's lift.
Concept context
Pressure, buoyancy, Bernoulli equation, viscosity, and surface tension.