MCQ Detailed View

Fuels are substances that release energy when they undergo combustion. The energy released per unit mass of fuel is called its energy value or calorific value. Different fuels have different energy values depending on their chemical composition and the type of bonds in their molecules.

Among common fuels, hydrogen has the highest energy value. Hydrogen produces approximately 142 megajoules per kilogram (MJ/kg) when burned with oxygen, which is much higher than gasoline (around 44 MJ/kg) or charcoal (around 30 MJ/kg). This high energy density is due to hydrogen’s simple molecular structure and the fact that its combustion produces only water, releasing a large amount of energy relative to its mass.

Gasoline is a hydrocarbon mixture commonly used in engines and vehicles. Its energy value is significant but lower than hydrogen. Charcoal, made from carbonized wood, also releases energy through combustion but has a lower calorific value compared to both hydrogen and gasoline.

Hydrogen is considered a clean fuel because it does not produce carbon dioxide during combustion, only water vapor, making it environmentally friendly. Its high energy value and low emissions make it ideal for future energy solutions, including fuel cells and clean vehicles.

Understanding which fuel has the highest energy value helps in chemistry, physics, and environmental science studies, as it connects chemical energy, energy efficiency, and sustainable fuel technologies. Knowledge of energy values also plays a critical role in choosing fuels for engines, power plants, and industrial applications.