- When two substances together form a compound then those substances cannot be physically separated
- The new substance cannot be physically separated
- Therefore, the new substance is a compound

Hence, the new substance is a compound
Question: Two pure substances combine to make a new substance. The new substance cannot be physically separated and has a different boiling point than each of the original substances. This new substance can best be classified as
Context: - When two substances together form a compound then those substances cannot be physically separated 
- The new substance cannot be physically separated