Final answer:
The dominant element connected to a hydrocarbon backbone is carbon, which forms the main chain to which hydrogen atoms are attached in these organic compounds.
Step-by-step explanation:
The dominant element connected to the hydrocarbon backbone is carbon. Hydrocarbons are organic compounds composed exclusively of carbon and hydrogen atoms. Carbon atoms form the backbone or main chain of a hydrocarbon molecule and hydrogen atoms are attached to this backbone. In various organic molecules, such as carbohydrates, carbon can form single, double, or triple bonds with other carbon atoms and can also bond with other elements like nitrogen, oxygen, and sulfur. However, the defining feature of a hydrocarbon is the carbon framework to which the hydrogens are attached. The number and arrangement of carbon and hydrogen atoms can vary, leading to the formation of different compounds, including those with ring structures or double bonds.