Which of the following statements about mixtures is correct?

The statement that mixtures can contain elements, compounds, or both is correct because mixtures are formed when two or more substances are combined without any chemical change occurring between them. This means that the individual components can retain their distinct identities and properties. A mixture can consist of various elements, such as a mix of metals, or various compounds, such as salt and sugar mixed together, or a blend of both elements and compounds, such as in air, which contains nitrogen (an element), oxygen (an element), and carbon dioxide (a compound). This characteristic of mixtures makes them versatile and practical in many applications, as they can be formed from a wide variety of substances, including elements and compounds in any combination.

In contrast, the other options present incorrect assertions about mixtures. Some mixtures can be homogeneous, but they can also be heterogeneous, meaning they do not have uniform composition throughout. Not all mixtures have the same properties throughout, as in the case of a salad, where you can see distinct components. Finally, mixtures can be separated into their individual components through physical means, such as filtration or distillation, which is a defining characteristic of mixtures as opposed to compounds.