Which of the following best describes chalk in terms of the classification of matter?

• A. A homogeneous mixture
• B. A pure substance (compound)
• C. A pure substance (element)
• D. A heterogeneous mixture

Answer: (D)

Verified step by step guidance

1. Understand the classification of matter: Matter can be classified as pure substances or mixtures. Pure substances include elements and compounds, while mixtures can be homogeneous or heterogeneous.
2. Recall that a pure substance (element) consists of only one type of atom, such as oxygen (O\_2) or gold (Au).
3. Recognize that a pure substance (compound) consists of two or more elements chemically combined in a fixed ratio, such as water (H\_2O) or carbon dioxide (CO\_2).
4. Identify that a homogeneous mixture has a uniform composition throughout, like salt dissolved in water, where you cannot distinguish different parts.
5. Note that a heterogeneous mixture has visibly different components or phases, such as chalk, which contains particles of calcium carbonate mixed with other materials, making it non-uniform in composition.