This statement is false. Corrected Version: All mixtures must contain multiple elements or compounds.
Work Step by Step
A mixture must contain multiple pure substances which retain their chemical properties. While many mixtures contain compounds, this is not always the case. For instance, there could be a mixture of inert Krypton and Xenon gas. Xenon and Krypton are not bonded, meaning that they are not compounds. However, there must be at least two elements for a mixture to exist since a mixture must contain multiple pure substances.