Question

The calorific value of a fuel is expressed in a unit called as__________.
(A) Kilojoule per liter
(B) Kilogram per milliliter
(C) Kilojoule per gram
(D) Kilojoule per kilogram

Answer 1

Hint: Calorific value expresses the heat obtained from one unit of the fuel. It helps us in differentiating between a good fuel and a bad one.

Complete step by step answer:
(1) The calorific value of fuel is the quantity of heat produced by its combustion.
(2) The calorific value is the total energy released as heat when a substance undergoes combustion with oxygen.
(3) The unit of calorific value is kilojoule per kilogram $(KJ/Kg).$
(4) The calorific values of some fuels are

Fuel	Calorific value of fuel
Cow dung	$8000KJ/Kg$
Cool	$33000KJ/Kg$
Petrol	$45000KJ/Kg$
Diesel	$45000KJ/Kg$

 (5) During the combustion process, water vapor is generated and heat is recovered by using certain techniques.
(6) The efficiency of fuel or food mainly depends on calorific value.
(7) If the value is high, its efficiency will also be high.
(8) If the value is low, its efficiency would also be decreased.
(9) Calorific value is directly proportional to its efficiency.
(10) It is very important to know about the calorific value of fuel to carry out day-to-day activities.
(11) It helps us to determine the amount of energy we transport.

Therefore, form the above explanation the correct option is (D) Kilojoule per kilogram.

Note:
Calorific value could be high or low corresponding to good and bad fuels respectively.