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Question

The fuel with highest calorific value in kJ /kg unit is-

The correct answer is Hydrogen

Understanding Fuel Calorific Value and Energy Output

The calorific value of a fuel is the total energy released as heat when a unit amount (mass or volume) of the fuel is completely burned in oxygen. It's a measure of how much energy we can get from a specific amount of fuel. The unit for calorific value by mass is commonly expressed in kilojoules per kilogram ($\text{kJ/kg}$). Different fuels release different amounts of energy when burned.

Comparing the Calorific Value of Common Fuels

Let's look at the approximate calorific values of the fuels listed in the options (CNG, LPG, Petrol, and Hydrogen) to determine which one yields the most energy per unit mass. Note that these values can vary slightly based on the exact composition and source of the fuel, but the relative ranking is generally consistent.

Fuel Approximate Calorific Value ($\text{kJ/kg}$)
CNG (Compressed Natural Gas) ~ 50,000
LPG (Liquefied Petroleum Gas) ~ 55,000
Petrol (Gasoline) ~ 45,000
Hydrogen ($\text{H}_2$) ~ 150,000

From the table, we can clearly see that Hydrogen has a significantly higher calorific value compared to CNG, LPG, and Petrol. Hydrogen's calorific value is roughly three times that of LPG, which is the next highest among the options provided. This means that burning one kilogram of Hydrogen releases about three times more energy than burning one kilogram of LPG.

Therefore, among the given options, Hydrogen is the fuel with the highest calorific value in $\text{kJ/kg}$ unit.

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