15. a. Medicine Medicine is generally a solution or mixture but not necessarily a colloid. On the other hand, marshmallows (foam), mayonnaise (emulsion), and styrofoam (solid foam) are all examples of colloids, where one substance is dispersed in another with particle sizes between solutions and suspensions.16. a. Sugar Sugar dissolves completely in water forming a true solution, not a suspension. Suspensions are mixtures where particles do not dissolve but remain suspended temporarily or settle over time. Peppercorns, pearl sinkers, and mongo seeds are insoluble solids that do not dissolve in water and can form suspensions.