Which property does a suspending agent primarily impart to the dispersion medium?

• A. Increases viscosity
• B. Decreases viscosity
• C. Increases solubility
• D. Decreases stability

Answer: (A)

The main thing a suspending agent does is increase the viscosity of the dispersion medium. By thickening the liquid, it creates a more resistant environment for the suspended particles, slowing their gravitational settling. According to the basic relation for settling velocity, higher viscosity reduces the rate at which particles fall, which helps keep the suspension uniform between shakes. This is why suspending agents are used—to enhance physical stability by preventing rapid sedimentation.

Increasing solubility would help dissolve the particles rather than keep them dispersed, and decreasing stability would defeat the purpose of a suspension. Decreasing viscosity would actually allow particles to settle faster, not slower. So the primary property imparted is increased viscosity.