Question

Which among the following g is considered as the cleanest fuel?
A. Cow dung cake
B. Petrol
C. Kerosene
D. Hydrogen

Answer 1

Hint: As the name suggests, the cleanest fuel is those fuels which emit fewer pollutants than other fossil fuel. Let us see the characteristics of the cleanest fuel: it must be easy to store and transport, it should burn smoothly without emitting harmful gases and it should not produce smoke.

Complete step by step answer:
Cleanest fuel which is derived from organic material should have moderate ignition temperature and it should also have high calorific value.
Now let us discuss calorific value in brief: It is the amount of heat release when one gram of fuel is completely burned in sufficient supply of oxygen. It is measured in kilojoules per gram.

=> Hydrogen gas when burning in the air produces water vapor and that is why it is the cleanest fuel that is completely non-polluting fuel.
Hydrogen fuel is suggested as convenient fuel because it is stored in the form of compressed gas or as a liquid.

Let us see other options in brief:
(A) Cow dung cake: By using animal husbandry cow dung cake is made and used as fuel and called Chulha in India. Cow dung cake is not considered as cleanest fuel because it consumes more oxygen and takes a long time to ignite.

(B) Petrol: Petrol is obtained from petroleum which is also called crude oil is naturally occurring yellowish black liquid in color, present beneath the Earth’s surface. By using fractional distillation, components of petroleum get separated. It is used as fuel to contribute to global warming and ocean acidification.

(C) Kerosene is also known as paraffin or lamp oil. It is combustible which is derived from petroleum. It is not considered as cleanest fuel because it can withstand a higher temperature before it vaporizes. It means combustion is not as easy as it is with gasoline.

Now among these four options, Hydrogen is considered as the cleanest fuel because it produces water vapor when it is burned in air. Hence, the correct option is (D).

Note: Remember, natural gas is one of the safest and cleanest fossils at present because during burning, most of the time it releases carbon dioxide along with water vapor.
Hydrogen gas is not used as fuel even though it has the highest caloric value because it becomes highly explosive when it comes in contact with air.