Question

Study the following table:

Fuel	Calorific value	State	Ignition temp.
A	High	Solid	High
B	Moderate	Gas	High
C	Moderate	Gas	Moderate
D	Low	Liquid	Low

Which is best suited as domestic fuel?
1. A
2. B
3. C
4. D

Answer 1

Correct Answer - Option 3 : C

Concept:

• Calorific value is the amount of heat energy present in food or fuel and which is determined by the complete combustion of specified quantity at constant pressure and in normal conditions.
• It is also called calorific power.
• The unit of calorific value is kilojoule per kilogram i.e. KJ/Kg.
• The efficiency of fuel or food mainly depends on the calorific value.
• If the value is high, its efficiency will also be high. If the value is low, its efficiency would also decrease.

Explanation:

• A good fuel is one which is readily available, cheap, burns easily in the air at a moderate rate, and produces a large amount of heat.
• The efficiency of the fuel is measured by its calorific value.
• As per given condition,

Fuel should have moderate calorific value, in gaseous state and moderate ignition temperature.

Given the table shows the calorific value of some fuels:

Fuel	Calorific Value (kJ/kg)
Cow dung cake	6000 - 8000
Wood	17,000 - 22,000
Coal	25,000 - 33,000
Petrol	45,000
Kerosene	45,000
Deisel	45,000
Methane	50,000
CNG	50,000
LPG	55,000
Biogas	35,000 - 40,000
Hydrogen	1,50,000