Which of the following statements about hydrocarbons is correct?

Hydrocarbons are organic compounds that primarily consist of carbon and hydrogen atoms. This characteristic is fundamental to their definition, as they are formed solely from these two elements. The simplest hydrocarbons, known as alkanes, are made up of only single bonds between the carbon atoms, and as the hydrocarbons become more complex, they can include various types of bonds such as double or triple bonds, but the inclusion of other elements is not part of the definition of hydrocarbons.

The other statements are not accurate for hydrocarbons. While some hydrocarbons may have different forms and structures (like alkenes or alkynes with double or triple bonds), the presence of double bonds is not a requirement for all hydrocarbons. Hydrocarbons can exist in various physical states—gas, liquid, or solid—depending on their molecular weight and structure, so they are not limited to solid form. Additionally, hydrocarbons do not form ionic bonds with metals; instead, they typically engage in covalent bonding. This further emphasizes the correctness of the statement that hydrocarbons consist only of carbon and hydrogen atoms.