Class VIII NCERT

1. Coal & Petroleum
Chapter – 5 , NCERT, Class – VIII
Presentation By: Prof. Malik Moazzam

2. Type of Resources:
We use various materials for our basic needs. Some of them are found in nature
and some have been made by human efforts. {Natural & Manmade}
Resources are mainly : -
Natural resources
Definition: The sources which are obtained from nature are called natural
resources.
Types of natural resources
1. Inexhaustible natural resources
These sources are present in unlimited quantity in nature and are not likely
to be exhausted by human activities.
Examples: Sunlight, air, etc.
2. Exhaustible natural resources
The amount of these resources in nature is limited, they can be exhausted
by human activities. [They are Renewable and Non-Renewable]
Examples: Forests, coal, petroleum. minerals, wild life, natural gas, etc.

3. Memory Map: Types of Natural Resources

4. Question?? “Do Yourself”
Can sunlight get exhausted by human activities?
Name some inexhaustible substances other than sunlight and air?
?
?
1. Which fuel is used for running vehicles?
(a) Wood (b) Coal (c) Diesel (d) Charcoal
2. Which of the following is a natural resource?
(a) Tea (b) Cooked food (c) Air (d) Toffee
3. inexhaustible natural resource in nature are
(a) limited (b) unlimited (c) scarce (d) not present
4. Which of the following is an exhaustible natural resource?
(a) Air (b) Water (c) Soil (d) Forest

5. Fuels
A fuel is any substance that releases large amounts of energy in the
form of heat and light when it is burned.
For example, coal and petroleum are fuels. Fuels can be classified as
natural (primary) fuels and derived (secondary) fuels. If a fuel Is present
in its natural state, it is called natural fuel. If a fuel is processed to
improve its quality, it Is called derived fuel.

6. Classification of Fuels

7. • Calorific value of a fuel
Calorific value of a fuel is the amount of heat liberated by complete
burning of a unit mass or volume of a fuel. For liquid or gaseous fuels,
volume of fuel is considered while for solid fuels mass of fuel is
considered to find out the calorific value.

8. Characteristics of a good fuel
• It should be economical.
• It should be available easily
• It should not emit poisonous gases on burning
• It should produce large amounts of heat with respect to its mass (it
should have a high calorific value)
• It should be easy to transport and handle
• It should not produce a bad odour
• It should be clean and should not produce many ashes
• It should not ignite easily at room temperature

9. Fossil Fuels
Exhaustible natural resources like coal, petroleum and natural gas were
formed from the dead remains of living organism (fossils). So, these are
called fossil fuels. Coal and petroleum are very important natural
resources and play a vital role in modem society. They are found in the
earth's crust.

10. Coal ;
The Story of Coal:
कोयला
“Coal is a complex
mixture of carbon,
hydrogen and
oxygen compounds.
Nitrogen, sulphur
and phosphorus
compounds are
also present in it. It
is found in coal
mines deep under
the surface of
earth”