ANSWER:
Hydrogen is the "dominant element" attached to the "carbon backbone".
Step-by-step 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.