18. What are the two classes of pure substances?
O A. Liquids and gases
O B. Aloms and molecules
O C. Elements and compounds
O D. Solutions and mixtures

Respuesta :

Final answer:

Elements and compounds are the two classes of pure substances in chemistry.


Explanation:

Elements and compounds are the two classes of pure substances. An element is a substance that cannot be broken down into simpler components, while a compound is made up of more than one type of atom.


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