Amorphous carbon is the most reactive form of carbon. Because amorphous carbon burns easily in air, it is used as a combustion fuel. There are two kinds of carbon compounds. The first is inorganic. Inorganic compounds are binary compounds of carbon with metals or metal carbides.
Carbon compounds containing nonmetals are usually gases or liquids with low boiling points.
Carbon monoxide, a gas, is odorless, colorless, and tasteless. Carbon dioxide is a colorless, almost odorless gas that is formed by the combustion of carbon. It is a product that results from respiration in most living organisms and is used by plants as a source of carbon. Frozen carbon dioxide, known as dry ice, is used as a refrigerant. Organic compounds are those compounds that occur in nature.