Which statement best describes an element in the classification of matter?

• A. A pure substance made of only one type of atom that cannot be broken down into simpler substances by chemical means
• B. A substance that has a uniform composition but can be separated into different substances by filtration
• C. A substance made of two or more elements chemically combined in a fixed ratio
• D. A physical combination of two or more substances that can be separated by physical means

Answer: (A)

Verified step by step guidance

1. Understand the classification of matter, which divides substances into elements, compounds, and mixtures based on their composition and properties.
2. Recall that an element is defined as a pure substance consisting of only one type of atom, and it cannot be broken down into simpler substances by chemical means.
3. Recognize that a compound is a pure substance made of two or more elements chemically combined in a fixed ratio, which is different from an element.
4. Identify that mixtures can be homogeneous (uniform composition) or heterogeneous, and they can be separated by physical means such as filtration.
5. Compare each statement to these definitions to determine which one correctly describes an element as a pure substance made of only one type of atom that cannot be chemically broken down.