Question

Which of the following is an ideal fuel?
(a)- Coal
(b)- LPG
(c)- Petrol
(d)- None of these

Answer 1

Hint: An ideal has some characteristics in which one of the main characters is there is no residue or any harmful emission after the usage of the ideal fuel. If there is even little emission or residue, then it is not an ideal fuel.

Complete answer:
Fuels are those compounds or liquids which are used to produce energy that can be converted into various forms of useful work, for example, petrol, fossil fuels, nuclear energy, etc.
Ideal fuel is a type of fuel that is also known as a good fuel. Some of the characteristics are the ideal fuel is easily available and cheap, at a moderate rate it can easily burn, it can release a good amount of usable energy, there is no emission of harmful substances which means it is an eco-friendly fuel. Its calorific value is also very high because the heat produced is very high.
So, we are given three compounds, i.e., Coal, LPG, and Petrol. Coal and petrol are fossil fuels which means there will be the emission of carbon dioxide gas and many more which is harmful to the environment. CNG is a very good fuel but it cannot be considered an ideal fuel because it doesn't show the exact properties of the ideal fuel. Therefore, all of them are not ideal gas.

Hence, the correct answer is an option (d)- None of these.

Note: The calorific value is also known as heat value and it is expressed in joules per kilogram, which is written as J/Kg. If the component doesn't have a high calorific value then it is a poor fuel.