Organic liquid with an aromatic smell which is carcinogenic and thus highly harmful. Benzene is the simplest compound based on the hexagonal carbon ring, the “benzene ring”. Its molecular formula is C6H6, which means that it is composed of six carbon atoms joined in a ring with one hydrogen atom attached to each. The names of a variety of substances can be traced to the term “benzene". Due to the aromatic odour of benzene, all organic molecules based on carbon rings are referred to as “aromatics", with the hexagon (the "benzene ring") being the most important and frequent but not the only aromatic ring. In German language, the word for petrol resp. gasoline is “Benzin”, which sounds like benzene. Actually, petrol contains a significant proportion of benzene, limited to 1% in most countries due to the toxicity of benzene. Since benzene rings are chemically highly stable, they are rarely broken down in chemical reactions.