Question

A given mass of fuel having a calorific value of 45,000 kJ/kg, on burning, produces 67,500 kJ of heat. The mass of the fuel used is:

• A. 1.5 kg
• B. 5 kg
• C. 2 kg
• D. 15 kg

Answer 1

The correct option is A 1.5 kg

Heat produced on burning the given amount of fuel = 67,500 kJ
Calorific value of fuel = 45,000 kJ/kg
Mass of fuel = ?

We know, $\mathrm{Calorific}\mathrm{value}\left(\mathrm{kJ}/\mathrm{kg}\right)=\frac{\mathrm{Amount}\mathrm{of}\mathrm{heat}\mathrm{produced}\left(\mathrm{kJ}\right)}{\mathrm{Mass}\mathrm{of}\mathrm{fuel}\left(\mathrm{kg}\right)}$
$\mathrm{Mass}\mathrm{of}\mathrm{fuel}=\frac{\mathrm{Amount}\mathrm{of}\mathrm{heat}\mathrm{produced}}{\mathrm{Calorific}\mathrm{value}}$ $=\frac{67,500\mathrm{kJ}}{45,000\mathrm{kJ}/\mathrm{kg}}=1.5\mathrm{kg}$