To determine which of the options is a pure substance, we need to understand the definitions of each term:
- Element: An element is a substance that cannot be broken down into simpler substances by chemical means. It consists of only one type of atom.
- Compound: A compound is made up of two or more different types of atoms that are chemically bonded together. Compounds have fixed compositions and distinct chemical properties.
- Mixture: A mixture consists of two or more substances that are physically combined but not chemically bonded. The components in a mixture can retain their individual properties.
Given this understanding:
- Option A: Element – This is a pure substance.
- Option B: Compound – This is also a pure substance.
- Option C: Mixture – This is not a pure substance.
- Option D: Both A and B – This is correct since both elements and compounds are classified as pure substances.
In conclusion, the correct answer is D) Both A and B, as both elements and compounds are considered pure substances.