A mixture is a substance made of more than one type of particle.

• A. Pure substance made of a single type of particle
• B. Substance made of more than one type of particle
• C. A gas only
• D. A crystalline solid

Answer: (B)

Mixing different substances creates something called a mixture because there are two or more kinds of particles present that aren’t chemically bonded to each other. In a mixture, each component keeps its own properties, and you can usually separate them by physical means like filtration, evaporation, or distillation. So describing a mixture as made of more than one type of particle fits perfectly.

That’s why this statement is the best match: it captures the essential idea that more than one kind of particle is involved. Pure substances, by contrast, are made of only one kind of particle (elements or compounds). A gas being the definition is too limiting, since mixtures can be gases, liquids, or solids. A crystalline solid isn’t a defining feature of a mixture either, because crystals can be either pure substances or mixtures (for example, alloys are crystalline mixtures).