Which statement best describes an element?

• A. An element is a substance that always contains carbon and hydrogen atoms.
• B. An element is a pure substance that cannot be broken down into simpler substances by chemical means.
• C. An element is a compound formed from two or more different atoms bonded together.
• D. An element is a mixture of two or more substances that can be separated by physical means.

Answer: (B)

Verified step by step guidance

1. Understand the definition of an element in chemistry: An element is a pure substance consisting of only one type of atom.
2. Recall that elements cannot be broken down into simpler substances by chemical reactions, unlike compounds which can be decomposed into elements.
3. Recognize that elements are not necessarily composed of carbon and hydrogen atoms; that description fits organic compounds, not elements in general.
4. Distinguish between elements, compounds, and mixtures: compounds contain two or more different atoms chemically bonded, while mixtures are physical combinations of substances that can be separated physically.
5. Conclude that the best description of an element is that it is a pure substance that cannot be broken down into simpler substances by chemical means.