Gasoline has the highest fuel value among the given options.



Fuel Value: Fuel value refers to the amount of energy that can be obtained from a given quantity of fuel. It is usually measured in terms of heat energy released per unit mass or volume of fuel. The higher the fuel value, the more energy can be obtained from the fuel.

Now, let's compare the fuel values of the given options:

Hydrogen:
- Hydrogen has a high fuel value due to its high energy content per unit mass.
- It has a fuel value of about 120-142 megajoules per kilogram (MJ/kg).
- However, hydrogen has a low energy content per unit volume, which affects its practicality as a fuel.

Charcoal:
- Charcoal is a solid fuel made from carbon-rich materials, such as wood or coal.
- It has a relatively lower fuel value compared to hydrogen and natural gas.
- The fuel value of charcoal is around 29-33 MJ/kg.

Natural Gas:
- Natural gas is a fossil fuel composed primarily of methane.
- It has a higher fuel value than charcoal but lower than gasoline.
- The fuel value of natural gas is approximately 35-55 MJ/kg.

Gasoline:
- Gasoline, also known as petrol, is a liquid fuel commonly used in vehicles.
- It has the highest fuel value among the given options.
- The fuel value of gasoline is around 44-46 MJ/kg.

Therefore, gasoline has the highest fuel value among hydrogen, charcoal, natural gas, and gasoline itself. It is widely used as a fuel for internal combustion engines due to its high energy content per unit mass.