Question

Which of the following is NOT regarded as a primary fuel?

• A. Natural gas
• B. Coal gas
• C. Lignite
• D. Crude oil

Hint:

A simple way to distinguish them: If you can dig it or pump it directly out of the ground and burn it, it's a Primary Fuel. If it requires a factory or a chemical plant to produce it from something else, it's a Secondary Fuel.

Answer 1

The Correct Option is B

Fuels are classified into two categories based on their occurrence and processing: Primary (Natural) and Secondary (Derived). 1. Primary Fuels: These are fuels found in nature and used in their natural form without any major chemical processing.

• Coal (including Lignite): Mined directly from the earth.

• Crude Oil (Petroleum): Extracted directly from underground reservoirs.

• Natural Gas: Found in underground deposits, often with petroleum.

• Wood/Biomass: Obtained directly from plants.

2. Secondary Fuels: These are derived from primary fuels through chemical or physical processes to make them more suitable for specific uses.

• Coal Gas: Produced by the destructive distillation of coal.

• Coke: Obtained from coal.

• Petrol/Diesel/Kerosene: Refined from crude oil.

3. Conclusion: Looking at the options, Natural gas, Lignite (a type of coal), and Crude oil are all primary fuels found directly in nature.

Coal gas is a manufactured product derived from coal, making it a secondary fuel.