Question

these can only be separated by chemical means.
options: stuff, compound, mixture, element

Explanation:

To determine the correct answer, we analyze the definitions:

• Element: A pure substance with one type of atom, cannot be broken down chemically.
• Mixture: Composed of two or more substances, separated by physical means (e.g., filtration, distillation).
• Compound: A pure substance with two or more elements chemically bonded, requiring chemical reactions (e.g., decomposition) to separate into elements.

The question states "can only be separated by chemical means," which matches the definition of a compound. "Stuff" is not a scientific term for this context.

Answer:

B. compound