Chemistry Regents Practice Test 2026 – Complete Prep Resource

A hydrocarbon is defined as an organic compound that consists exclusively of hydrogen and carbon atoms. This characteristic is fundamental to their classification. Hydrocarbons can vary in structure, forming different types such as alkanes, alkenes, and alkynes, depending on the types of bonds present between the carbon atoms (single, double, or triple bonds). These compounds are the primary components of fossil fuels and serve as crucial building blocks in organic chemistry.

In contrast, the other choices refer to entirely different concepts. For example, compounds comprising nitrogen and oxygen would not fit the definition of hydrocarbons, as they contain elements other than carbon and hydrogen. Similarly, compounds formed by the reaction between metals and nonmetals denote ionic or metallic bonds, which again do not involve only hydrogen and carbon. Lastly, the description of a gas forming at high temperatures does not align with the structural and elemental specificity required to define a hydrocarbon. Thus, the first choice is the only one that accurately captures the essence of hydrocarbons.