Coal and Petroleum Class 8 Extra Questions and Answers Free PDF Download
FAQs on CBSE Important Questions for Class 8 Science Coal and Petroleum - 2025-26
1. What are fossil fuels, and what are the three main types discussed in Chapter 3?
Fossil fuels are natural fuels formed from the remains of ancient living organisms buried deep under the Earth over millions of years. For the CBSE Class 8 exams, the three main types you must know are coal, petroleum, and natural gas.
2. What are the important products obtained from the destructive distillation of coal?
The destructive distillation of coal (heating it in the absence of air) is a crucial process. The three main products to remember for exams are:
- Coke: A tough, porous, and black substance. It is an almost pure form of carbon used in steel manufacturing.
- Coal Tar: A thick black liquid with an unpleasant smell, used to make dyes, drugs, perfumes, and plastics.
- Coal Gas: A flammable gas produced during the process, used as a fuel in industries.
3. List the key fractions obtained during the refining of petroleum and one major use for each.
Petroleum refining separates crude oil into useful substances called fractions. Important fractions and their uses for the exam include:
- LPG (Liquefied Petroleum Gas): Fuel for home and industry.
- Petrol: Fuel for light motor vehicles.
- Kerosene: Fuel for stoves and jet aircraft.
- Diesel: Fuel for heavy motor vehicles and electric generators.
- Lubricating Oil: Used for lubrication.
- Paraffin Wax: Used in ointments, candles, and Vaseline.
- Bitumen: Used for paving roads and in paints.
4. Why is petroleum called 'black gold'?
Petroleum is called 'black gold' due to its immense commercial value and wide range of uses. Like gold, it is a highly valuable commodity. Its black colour comes from its crude, unrefined state. From it, we derive numerous essential products like petrol, diesel, and raw materials for plastics and chemicals, making it a cornerstone of the modern industrial economy. This is a common question to test conceptual understanding.
5. What is the difference between coke and coal?
The key difference to state in an exam is that coal is a naturally occurring fossil fuel, while coke is a man-made product derived from it. Coke is produced by heating coal to high temperatures in the absence of air. As a result, coke is almost a pure form of carbon (about 98%), whereas coal contains many impurities along with carbon.
6. If fossil fuels are formed from dead organisms, why don't we see them forming in our local soil or ponds today?
This is a high-order thinking question. The formation of fossil fuels like coal and petroleum requires very specific conditions that are not present today. These conditions, which occurred millions of years ago, include:
- Enormous amounts of organic matter being buried rapidly.
- Absence of air, which prevents complete decomposition.
- Extreme heat and pressure from the layers of earth above, which slowly transform the organic matter.
7. According to the CBSE Class 8 syllabus for 2025-26, what are the major disadvantages of burning fossil fuels?
Burning fossil fuels has several major disadvantages that are important for exams. The key points are:
- Air Pollution: Burning coal and diesel releases harmful gases like sulphur dioxide and nitrogen oxides, which can cause respiratory problems and acid rain.
- Global Warming: Fossil fuels release large amounts of carbon dioxide (CO2), a major greenhouse gas that traps heat and contributes to the rise in global temperatures.
- Resource Depletion: They are non-renewable resources, meaning they are limited and will eventually run out.
8. Natural gas is often found alongside petroleum. From an exam perspective, why is it considered a better fuel than coal or petroleum products?
Natural gas, particularly in the form of Compressed Natural Gas (CNG), is often considered a 'cleaner' or better fuel for two main reasons:
- Less Pollution: It burns more completely and produces significantly fewer harmful gases like sulphur dioxide, nitrogen oxides, and unburnt carbon particles compared to petrol, diesel, or coal.
- Convenience: It can be transported easily through pipelines directly to homes and factories, which is a major advantage.
9. What important steps does the Petroleum Conservation Research Association (PCRA) suggest for saving petrol/diesel while driving?
The PCRA provides several tips to conserve fuel, which are important to remember. Key suggestions include:
- Drive at a constant and moderate speed as far as possible.
- Switch off the engine at traffic lights or at a place where you have to wait.
- Ensure correct tyre pressure.
- Ensure regular maintenance of the vehicle.
10. Besides fuel, what are some unexpected but important industrial materials derived from petroleum?
While fuels are the most common product, petroleum is also the source of many valuable substances called 'petrochemicals'. These are used to manufacture a wide range of important industrial materials, including:
- Plastics (like polythene and PVC)
- Detergents
- Synthetic fibres (like polyester, nylon, and acrylic)
- Fertilizers (like urea)
- Synthetic rubber
