what do pure substances and mixtures have in common

Pure substances are made up of one type of atom or molecule only (resulting in elements or compounds). For example, sodium is a pure substance and is composed of sodium atoms only. Similarly, table salt (or sodium chloride) is composed of NaCl molecules only. In comparison, a mixture is composed of two or more pure substances in a non-fixed ratio. Pure substances cannot be separated out into any other form. Mixtures, on the other hand, can be separated out into individual pure substances by physical processes.
From the above, it is clear that both pure substances and mixtures contain atoms. Furthermore, both of these contain at least one pure substance. Both pure substances and mixtures have properties like weight, color, volume, flammability, toxicity, etc. Similarly, a pure substance and a homogeneous mixture will have the same properties throughout the entire substance or mixture.
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