Question

which statement about pure substances and molecules is correct? (1 point) all pure substances are molecules pure substances cannot be molecules molecules cannot be pure substances all molecules are pure substances

Explanation:

1. Analyze "All pure substances are molecules": Pure substances can be elements (e.g., metals like Na, which are in atomic form, not molecular) or compounds. So this is wrong.
2. Analyze "Pure substances cannot be molecules": Compounds like H₂O (water) are pure substances and are molecules. So this is wrong.
3. Analyze "Molecules cannot be pure substances": Molecules of compounds (e.g., H₂O) or diatomic elements (e.g., O₂) are pure substances. So this is wrong.
4. Analyze "All molecules are pure substances": A molecule is a group of atoms bonded together. If a molecule is of a single compound (e.g., H₂O) or a diatomic element (e.g., O₂), it's a pure substance. Even if we consider a molecule from a pure substance (like O₂ molecules in O₂ gas), they are part of a pure substance, and the molecule itself represents a pure - substance - forming entity. So this statement is correct.

Answer:

All molecules are pure substances