Pharmaceutics II Exam 2 Concepts Practice Test

Oil-in-water emulsions have oil as the dispersed phase and water as the continuous phase. The tiny oil droplets are spread throughout the continuous water phase, so the system is characterized by droplets of oil suspended in water. This arrangement makes the emulsion appear milky or opaque and allows it to mix with more water easily. Emulsifiers with hydrophilic heads help keep the oil droplets from coalescing at the oil–water interface.

The other descriptions don’t fit: water droplets dispersed in oil describe a water-in-oil emulsion, not O/W. Being water-free would contradict the defining continuous water phase. Gas emulsions involve gas droplets (foams) rather than oil droplets in water.