What needs to be added to a suspension when the active ingredient is a hydrophobic powder?

• A. Wetting agent
• B. Flavoring
• C. Colorant
• D. Preservative

Answer: (A)

When the active ingredient is a hydrophobic powder, the main need is to improve wetting and dispersion in water. Hydrophobic particles resist being wetted by aqueous liquids, so they tend to clump and settle rather than form a uniform suspension. A wetting agent acts as a surfactant, lowering the interfacial tension between the powder and the liquid and coating particle surfaces. This allows water to spread over and penetrate the powder, breaking up agglomerates and producing a stable, evenly dispersed suspension. Flavoring, colorant, and preservative may be added for taste, appearance, or microbial stability, but they do not address the dispersion of hydrophobic particles, which is why a wetting agent is the appropriate choice here.