The correct option is (c) 1 and 3 only.
Explanation
The efficiency of a fuel is determined by the amount of heat energy produced upon the complete combustion of a specific quantity of that fuel. This measure is known as the calorific value.
Statement-wise Analysis:
- Statement 1 is Correct: Fuel efficiency is quantitatively expressed in terms of its calorific value. The calorific value represents the amount of heat energy produced on the complete combustion of 1 kg of a fuel. It is typically expressed in units of kilojoules per kilogram (kJ/kg).
- Statement 2 is Incorrect: A fuel with a higher calorific value produces more heat per unit mass, not less. A higher value indicates that the fuel is more efficient in terms of energy output for a given mass.
- Statement 3 is Correct: Hydrogen has the highest calorific value among common fuels. The calorific value of Hydrogen is approximately 150,000 kJ/kg, whereas the calorific value of Diesel is approximately 45,000 kJ/kg. Therefore, Hydrogen produces significantly more energy per unit mass compared to Diesel.
Key Takeaway:
Calorific value is the primary indicator of fuel efficiency, measured in kJ/kg. Hydrogen possesses an exceptionally high calorific value (150,000 kJ/kg) compared to hydrocarbon fuels like petrol (45,000 kJ/kg) and diesel (45,000 kJ/kg).