Which term describes a pure substance that cannot be broken down by chemical means into other substances?

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

Answer: (B)

Verified step by step guidance

1. Understand the definitions of the terms involved: A 'pure substance' is a material with a constant composition and distinct properties.
2. Recall that a 'mixture' consists of two or more substances physically combined, which can be separated by physical means.
3. Know that a 'compound' is a pure substance composed of two or more elements chemically combined in fixed proportions, which can be broken down into simpler substances by chemical means.
4. Recognize that an 'element' is a pure substance that cannot be broken down into simpler substances by chemical means because it consists of only one type of atom.
5. Conclude that the term describing a pure substance that cannot be broken down chemically is 'element'.