Class 8th Science Chapter 3
📘 Chapter Notes: Coal and Petroleum
🔹 1. Introduction to Natural Resources
🌍 Types of Natural Resources
(1) Inexhaustible Natural Resources
Available in unlimited quantity.
Example: Air, Sunlight.
(2) Exhaustible Natural Resources
Limited in nature.
Can be exhausted by human activities.
Example: Coal, Petroleum, Natural Gas, Forests, Wildlife.
🔥 2. Fossil Fuels
📖 Definition: Fossil fuels are fuels formed from the dead remains of plants and animals millions of years ago.
Coal
Petroleum
Natural Gas
⭐ One Line Fact: Fossil fuels are exhaustible and non-renewable resources.
💎3. Coal
📖 Definition:
Coal is a hard, black fossil fuel formed from dead vegetation over millions of years.
🕰 Formation of Coal
Formed about 300 million years ago.
Dead plants buried under soil.
High temperature & pressure converted them into coal.
Process is called Carbonisation.
📖 Definition of Carbonisation:
The slow process of conversion of dead vegetation into coal under high pressure and temperature.
🔬 Products of Coal
| Product | Uses |
|---|---|
| Coke | Manufacture of steel, extraction of metals |
| Coal Tar | Dyes, drugs, plastics, paints, naphthalene balls |
| Coal Gas | Fuel in industries |
📌 Important Definitions
Coke – Almost pure form of carbon.
Coal Tar – Thick black liquid with unpleasant smell.
Coal Gas – Gas obtained during coke preparation.
🔁 Repeated Question
Q1. Describe formation of coal.
Answer: Coal was formed about 300 million years ago from dense forests buried under soil. Due to high pressure and temperature, dead plants slowly converted into coal. This process is called carbonisation.
🛢 4. Petroleum
📖 Definition: Petroleum is a dark oily liquid fossil fuel found between layers of rocks under the Earth.
🕰 Formation:
Formed from dead marine organisms.
Buried under sand and clay.
High pressure & temperature converted them into petroleum and natural gas.
🌎 Important Dates
1859 – First oil well drilled in Pennsylvania, USA
1867 – Oil found at Makum in Assam, India.
🗺 Petroleum in India
Found in:
Assam
Gujarat
Mumbai High
Godavari Basin
Krishna Basin
🏭 Refining of Petroleum
📖 Definition: Refining is the process of separating different constituents of petroleum.
Done in a Petroleum Refinery.
📊 Constituents & Uses
| Constituent | Uses |
|---|---|
| LPG | Fuel for home & industry |
| Petrol | Motor fuel |
| Kerosene | Fuel for lamps & stoves |
| Diesel | Heavy vehicles |
| Lubricating Oil | Lubrication |
| Paraffin Wax | Candles, ointments |
| Bitumen | Road surfacing |
⭐ One Line Fact:
Petroleum is called Black Gold due to its high commercial value.
🌬 5. Natural Gas
📖 Definition: Natural gas is a clean fossil fuel stored under high pressure.
🔹 CNG (Compressed Natural Gas)
Least polluting fuel.
Used in vehicles.
Supplied through pipelines.
📍 Found in India:
Tripura
Rajasthan
Maharashtra
Krishna-Godavari Delta
⭐ Advantages of CNG & LPG
Clean fuel
Less pollution
Easy transport
High calorific value
🌡 6. Conservation of Fossil Fuels
Why Limited?
Took millions of years to form.
Will last only few hundred years.
Burning causes pollution & global warming.
🏢 Organization
Petroleum Conservation Research Association (PCRA)
PCRA Tips:
Drive at constant speed
Switch off engine at traffic lights
Maintain correct tyre pressure
Regular vehicle maintenance
📌 Important Keywords
Fossil Fuel
Carbonisation
Coke
Coal Tar
Refinery
Black Gold
CNG
LPG
📍 Map Work (For Exam)
Mark on India Map:
Coal: Jharkhand, Chhattisgarh
Petroleum: Assam, Gujarat, Mumbai High
Natural Gas: Tripura, Krishna Godavari Basin
🔁 Very Important Repeated Questions with Answers
Q1. Why are fossil fuels exhaustible?
Because they are limited and take millions of years to form.
Q2. Name petroleum product used for road surfacing.
Bitumen.
Q3. Least polluting fuel?
CNG.
Q4. Define carbonisation.
Conversion of dead vegetation into coal under high pressure and temperature.
Q5. Why petroleum is called black gold?
Because of its high commercial importance.
🎯 Summary (Exam Revision)
✔ Coal, Petroleum & Natural Gas are fossil fuels.
✔ Formed from dead organisms millions of years ago.
✔ Non-renewable & exhaustible.
✔ Should be used judiciously.
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