Which statement best defines a mixture?

• A. A substance with definite composition
• B. Consists of two or more different elements and/or compounds physically intermingled
• C. Cannot be separated into components
• D. Composed of a single element

Answer: (B)

A mixture is formed when two or more substances are combined without forming new chemical bonds, so each component keeps its own identity and properties. Because of that, the components can usually be separated again by physical methods such as filtration, distillation, or simple decanting.

The statement that best defines a mixture is that it consists of two or more different elements and/or compounds physically intermingled. This captures the idea that the substances are not chemically bonded and retain their separate identities within the combination.

The other statements describe pure substances rather than mixtures: a substance with definite composition refers to a pure substance, not a mixture; a single element is also a pure substance; and the claim that mixtures cannot be separated would misrepresent the fact that mixtures can typically be separated by physical means.