Question 21

A two-phase system of finely divided insoluble particles dispersed in a liquid is known as a suspension.

A suspension is characterized by the presence of solid particles that do not dissolve but remain dispersed within a liquid medium. This definition aligns perfectly with the concept of a two-phase system, where the solid particles are the dispersed phase and the liquid is the continuous phase.

A) emulsion

An emulsion consists of two immiscible liquids where one liquid is dispersed in the other. It typically involves a mixture of oil and water, which does not fit the definition of finely divided insoluble particles in a liquid, thus making this option incorrect.

B) tincture

A tincture is an alcoholic extract of a plant or a solution of medicinal substances in alcohol. It does not refer to a suspension of solid particles in a liquid, as tinctures are generally clear solutions rather than mixtures containing suspended particles, leading to this option being incorrect.

C) suspension

A suspension is indeed the correct answer as it describes a system where solid particles are finely divided and dispersed in a liquid. This matches the definition provided in the question, confirming that a suspension is a two-phase system consisting of insoluble particles in a liquid.

D) solution

A solution is a homogeneous mixture where solutes are completely dissolved in a solvent, resulting in no visible particles. This contradicts the concept of a two-phase system with insoluble particles, thus making this option incorrect.

Conclusion

Suspensions are defined by the presence of solid particles dispersed in a liquid, which accurately matches the question's description of a two-phase system. Options A, B, and D are incorrect as they refer to different types of mixtures or solutions that do not contain finely divided insoluble particles. Thus, option C is definitively the right choice based on the characteristics outlined in the question.