Carbon plus oxygen can make several different compounds, depending on the proportions and conditions in which they react. Some of the possible compounds include:

- Carbon monoxide (CO): This is a poisonous gas that is produced by the incomplete combustion of carbon-based fuels. It is a major air pollutant and can cause health problems such as headaches, nausea, and even death.

- Carbon dioxide (CO2): This is a colorless, odorless gas that is produced by the complete combustion of carbon-based fuels. It is also released by living organisms as a waste product of respiration. Carbon dioxide is a greenhouse gas that contributes to climate change.

- Carbonic acid (H2CO3): This is a weak acid that is formed when carbon dioxide dissolves in water. It is found in many natural waters, such as rivers, lakes, and oceans. Carbonic acid can react with other chemicals to form various carbonates and bicarbonates.

- Organic compounds: These are compounds that contain carbon and hydrogen, along with other elements such as oxygen, nitrogen, and sulfur. Organic compounds are the building blocks of all living things and are found in a wide variety of materials, such as wood, paper, and plastic.