What are mixtures?

Mixtures are defined as substances that contain two or more different elements or compounds that are not chemically bonded to each other. This means that in a mixture, each component retains its own individual properties and can be present in varying proportions. For example, in a mixture of sand and salt, both materials maintain their distinct characteristics and can be separated from each other using physical methods, such as dissolving the salt in water.

This definition contrasts with pure substances, which have a fixed composition and specific properties. In a mixture, the components can be mixed in any proportion, and the resulting mixture will not have a uniform composition throughout. This allows for a diverse range of physical properties depending on the components of the mixture.

The other choices describe different types of substances that do not capture the essence of mixtures. For instance, substances with a fixed composition refer to compounds or pure elements, while homogenous substances imply a uniform composition, which applies to solutions but excludes the variable nature of mixtures.