How is a mixture defined in chemistry?

A mixture in chemistry is defined as a physical combination of two or more substances that retain their individual properties. This means that when substances are mixed together to form a mixture, they do not undergo a chemical change, and each component maintains its characteristic properties, such as appearance, melting point, boiling point, and chemical reactivity.

For instance, when sand is mixed with salt, both the sand and salt can be seen and separated from one another, demonstrating that they retain their unique properties. The resulting mixture can be separated through physical means, such as filtration or evaporation, highlighting the absence of a permanent change in the composition of the original substances.

In contrast, options that describe a uniform composition of substances or transformations that alter properties do not accurately encapsulate the essence of a mixture. A solution that cannot be separated implies a homogeneous mixture, yet the defining characteristic of a mixture as a whole includes both homogeneous and heterogeneous types, where components can be distinctly identified and physically separated. Thus, the defining traits of mixtures center on their physical nature and the retention of individual properties of the substances involved.