Correct Option
The fuel value of a substance is its calorific value, which quantifies the amount of heat energy released upon the complete combustion of a unit mass (typically 1 kg) of the fuel. Among the given options, Hydrogen exhibits the highest calorific value, approximately 141,790 kJ/kg. This high energy yield, combined with its combustion product being primarily water vapor, positions it as an exceptionally clean and efficient fuel.
Incorrect Options
The calorific values for the other options are substantially lower than that of Hydrogen:
- Charcoal: Approximately 29,600 kJ/kg. As a solid fuel, it has a moderate calorific value and is mainly composed of carbon.
- Natural gas: Approximately 43,000 kJ/kg. Primarily methane, it is a gaseous fuel known for its relatively clean combustion compared to other fossil fuels, but its energy density per unit mass is less than hydrogen.
- Gasoline: Approximately 47,300 kJ/kg. This liquid fossil fuel is extensively used in internal combustion engines. While it possesses a higher energy density than charcoal and natural gas, its fuel value remains significantly lower than hydrogen.