Final answer:
Gold, pure water, and carbon dioxide are classified as pure substances. Gold is an element and pure water and carbon dioxide are compounds. Soil is a heterogeneous mixture, while pure air (contaminant-free), salt water, and bronze are homogeneous mixtures.
Step-by-step explanation:
When looking at the list provided (salt, pure water, soil, salt water, pure air, carbon dioxide, gold, and bronze), we can classify them into elements, compounds, homogeneous mixtures, or heterogeneous mixtures based on their properties. Here's the classification:
- Gold - Element
- Pure water - Compound
- Carbon dioxide - Compound
- Salt (if referring to table salt, NaCl) - Compound
- Pure air (if referring to contaminant-free air, which consists mainly of nitrogen and oxygen) - Homogeneous mixture
- Salt water - Homogeneous mixture
- Soil - Heterogeneous mixture
- Bronze (an alloy of copper and tin) - Homogeneous mixture
Remember, a pure substance has a constant composition and consistent properties throughout the sample. It includes elements like gold and compounds like carbon dioxide. Elements are composed of a single type of atom and cannot be broken down into simpler substances chemically. Compounds are made up of more than one type of atom. Mixtures, on the other hand, combine elements and/or compounds physically and can be separated into their component parts; they include both homogeneous mixtures, which are uniform throughout, like salt water, and heterogeneous mixtures, which are not uniform, like soil.