What distinguishes soluble powders (SP) from wettable powders (WP)?

Soluble powders (SP) differ from wettable powders (WP) primarily in their composition and behavior when mixed with water. SP consists of formulations that dissolve completely when mixed with a liquid, forming a clear solution. This is significant because it allows for uniform distribution of the active ingredient without leaving visible residues once applied and dried. Therefore, option C highlights that SP is indeed less visible after drying, which sets it apart from WP.

Wettable powders, on the other hand, do not fully dissolve in water but instead remain dispersed as fine particles that can settle over time. They require continuous agitation during application to maintain an even distribution but can leave a visible residue after the application process. This fundamental difference in the physical state once dried is what clarifies the characteristics of soluble powders versus wettable powders.