Which of the following cannot be chemically broken down into simpler substances?

• A. Compound
• B. Element
• C. Solution
• D. Mixture

Answer: (B)

Verified step by step guidance

1. Understand the definitions: A compound is a substance made of two or more elements chemically combined in a fixed ratio, and it can be broken down into simpler substances (elements) by chemical means.
2. An element is a pure substance that consists of only one type of atom and cannot be broken down into simpler substances by chemical methods.
3. A mixture is a physical combination of two or more substances that are not chemically combined and can be separated by physical means.
4. Identify that the question asks which substance cannot be chemically broken down into simpler substances, so focus on the fundamental nature of each option.
5. Conclude that since elements are the simplest form of matter and cannot be chemically decomposed, the correct answer is an element.