Washington Esthetician State Board Practice Exam 2025 – Complete Prep Resource

An emulsion is accurately defined as a mixture of two or more immiscible substances (such as oil and water) that are combined with the help of a binder or emulsifier. The emulsifier plays a crucial role by reducing the surface tension between the two immiscible liquids, allowing them to remain mixed over an extended period. This characteristic is particularly important in the cosmetic and skin care industries, where emulsions are commonly used in creams, lotions, and serums. The unique properties of emulsions allow for the effective delivery of active ingredients to the skin, enhancing the product's efficacy.

The other options do not correctly describe an emulsion. The first option refers to soluble substances, which do not apply to the concept of emulsions as they are specifically concerned with immiscible substances. The second option inaccurately describes a suspension rather than an emulsion, which involves solid particles dispersed in liquid. Lastly, the fourth option points to a gel-like substance, which is completely different in composition and function from an emulsion, as gels typically consist of a thickened liquid rather than a blend of immiscible liquids.