Hydrogen is the "dominant element" attached to the "carbon backbone".
EXPLANATION:
The backbone is referred to as hydrocarbon because it is made only out of hydrogen and carbon.
Hydrocarbon is currently one of the primary sources of energy as it is used as a "combustible fuel source". It is one of the major source of the world’s heat and electric energy sources.
Hydrocarbon is burned and the heat it generates is used to power machinery and vehicles.
They require oxygen for combustion and emits off carbon dioxide and heat during the combustion process.
