NCERT Solutions for Class 8 Science
Chapter 3, Coal and Petroleum
June 7, 2024, by Md. Farrukh Asif
A brief history of coal:
Coal, widely recognized as the most abundant fuel within the fossil fuel group, boasts a rich and diverse historical background. Its usage for heating dates back to prehistoric times, with evidence of the Romans in England utilizing it during the second and third centuries (100-200 AD). The English in the 1700s discovered that coal could produce a fuel that burned cleaner and hotter than wood charcoal.
In North America during the 1300s, the
Hopi Indians used coal for various purposes including cooking, heating, and
baking pottery made from clay. Subsequently, coal was rediscovered in the
United States by explorers in 1673.
Click the below links to know more……
|
REPRODUCTION IN ANIMALS NIMALS
Chap 6 |
The Industrial Revolution played a
pivotal role in extending the use of coal. Notably, James Watt's invention of
the steam engine facilitated the performance of tasks previously carried out by
humans and animals. Watt employed coal to generate the steam that powered his
engine.
Petroleum:
The
ancient Chinese were already using petroleum more than 2000 years ago. The I
Ching, one of the earliest Chinese writings, mentions that oil in its raw
state, without any refining, was initially found, extracted, and utilized in
China during the first century BCE.
Fossil Fuel:
Coal,
Petroleum and Natural Gas were formed from the dead remains of living organisms
(fossils).
Petroleum:
Petrol
and diesel are obtained from a natural resource called petroleum. The word
petroleum is derived from petra (rock) and oleum (oil) as it is mined from
between the rocks under Earth.
Petroleum
was formed from organisms living in the sea. After death, their bodies settled
at the bottom of the sea and got covered with layers of sand and clay. Over
millions of years, the absence of air, high temperature and high pressure
transformed the dead organisms into petroleum and natural gas.
Refining of Petroleum:
Petroleum
is a dark oily liquid. It has an unpleasant odour. It is a mixture of various
constituents such as petroleum gas, petrol, diesel, lubricating oil, paraffin
wax, etc.
The
world’s first oil well was drilled in Pennsylvania, USA, in 1859.
In
India, oil is found in Assam, Gujarat, Mumbai High and in the river basins of
Godavari and Krishna
Key Words:
COAL,
COAL GAS, COAL TAR, COKE, FOSSIL FUEL, NATURAL GAS, PETROLEUM, PETROLEUM
REFINERY.
What we have learnt now:
·
Coal, petroleum and natural gas are fossil
fuels.
·
Fossil fuels were formed from the dead
remains of living organisms millions of years ago.
·
Fossil fuels are exhaustible resources.
·
Coke, coal tar and coal gas are the products
of coal.
·
Petroleum gas, petrol, diesel, kerosene,
paraffin wax, lubricating oil are obtained by refining petroleum. Coal and petroleum resources are limited. We
should use them judiciously.
NCERT Solutions for Class 8 Science Chapter 3 Coal and Petroleum
Question 1.
What
are the advantages of using CNG and LPG as fuels?
Answer:
The
advantages of using CNG and LPG as fuels are:
They burn with a smokeless flame and so does not cause any pollution.
They
leave no ash on burning.
They
are easy to handle and convenient to store.
Question 2.
Name
the petroleum product used for surfacing of roads.
Answer:
Bitumen
Question 3.
Describe
how coal is formed from dead vegetation. What is this process called?
Answer:
Millions
of years ago, trees, plants, ferns and forests got buried below the rocks, soil
and sand due to natural processes like flooding, earthquake, etc. Slowly, as
more soil deposited over them, they were compressed. This led to the conditions
of high pressure and heat. These conditions along with the anaerobic conditions
turned the carbon-enriched organic matter of wood into coal.
This
slow process of conversion of wood into coal is called carbonisation.
Question 4.
Fill
in the blanks.
(a)
Fossils fuels are ____ , ____ and ____
(b)
Process of separation of different constituents from petroleum is called ______
(c)
Least polluting fuel for vehicle is ______
Answer:
(a)
coal, petroleum, natural gas
(b)
refining
(c)
CNG
Question 5.
Tick
True/False against the following statements.
(a)
Fossil fuels can be made in the laboratory.
(b)
CNG is more polluting fuel than petrol.
(c)
Coke is an almost pure form of carbon.
(d)
Coal tar is a mixture of various substances.
(e)
Kerosene is not a fossil fuel.
Answer:
(a)
False
(b)
False
(c)
True
(d)
True
(e)
False
Question 6.
Explain
why fossil fuels are exhaustible natural resources.
Answer:
Fossil
fuels take millions of years to be formed. They are limited in nature and
cannot be replenished easily, once consumed. Hence, they are considered as
exhaustible natural resources.
Question 7.
Describe
the characteristics and uses of coke.
Answer:
Characteristics
of Coke: Coke is 98% pure carbon. It is a tough, porous and black substance. It
produces very little smoke.
Uses
of Coke: Coke is very useful as fuel. It is a good reducing agent. It is widely
used in metallurgical processes to reduce metals from their oxides. It is used
for producing water gas.
Question 8.
Explain
the process of the formation of petroleum.
Answer:
Petroleum
is formed by the burial of aquatic plants and animals below the sea bed. The
marine animals and plants died thousands of years ago and settled down in the
bottom of sea. In anaerobic conditions, microorganisms decompose this organic
matter. Due to high pressure and heat, the dead remains of tiny plants and
animals were slowly converted into petroleum.
Question 9.
The
following Table shows the total power shortage in India from 1991–1997. Show
the data in the form of a graph. Plot shortage percentage for the years on the
Y-axis and the year on the X-axis.
S. No. Year Shortage (%)
1 1991 7.9
2 1992 7.8
3 1993 8.3
4 1994 7.4
5 1995 7.1
6 1996 9.2
7 1997 11.5
Answer:
Activity 3.1
Make
a list of various materials used by us in daily life and classify them as
natural and man-made.
Solution:
Natural Man-made
Air Clothes
Sunlight Furniture
Water Home
Minerals Cement
Forests Cosmetics
Activity 3.2
Take
some containers. Fill them with popcorn/peanuts/roasted gram/tof¬fees. Divide
students into groups of seven each. Further divide each group into three
subgroups containing 1, 2 and 4 students. Label them as first, second and third
generation respectively.
These
sub-groups represent the consumers. As the population is growing, second and third
generations have larger number of consumers.
Put
one full container for each group on a table. Ask consumers of the first
generation from each group to consume eatables from the container of their
group. Now, ask the second-generation consumers from each group to do the same.
Ask students to observe carefully the availability of eatables in each
container. If something is left in the containers, ask third generation from
each group to consume it. Now, finally, observe whether all the consumers of the
third generation got the eatables or not. Also, observe if anything is still
left in any of the containers.
Solution:
Students
should perform this activity themselves in their classroom.
Asking 1 Mark Questions and Answers in their classroom.
Question 1.
Name
the petroleum product used for surfacing of roads.
Answer:
Bitumen.
Question 2.
What
is the slow process of conversion of dead vegetation into coal called ?
Answer:
Carbonisation.
Question 3.
Fill
in the blanks :
Fossil fuels are ……, ……. and ……..
Process
of separation of different constituents from petroleum is called ………
Least
polluting fuel for vehicle is ………..
Answer:
coal, petroleum, natural gas
refining
CNG.
Question
4.
Tick
True/False against the following statements :
(a) Fossil fuels can be made in the laboratory. (T/F)
(b) CNG
is a more polluting fuel than petrol. (T/F)
(c) Coke
is almost pure form of carbon. (T/F)
(d) Coal
tar is a mixture of various substances. (T/F)
(e) Kerosene
is not a fossil fuel. (T/F)
Answer:
(a) False
(b) False
(c) True
(d) True
(e) False
Question 5.
Explain
why fossil fuels are exhaustible natural resources.
Answer:
Fossil
fuels are exhaustible natural resources because they will be exhausted by human
activities as they are limited in nature.
Question 6.
What
are natural resources?
Answer:
Material
obtained from nature is called natural resources, i.e. Air, Sunlight etc.
Question 7.
Classify
the following as exhaustible and inexhaustible natural resources-
air,
sunlight, water, forests, wildlife, coal.
Answer:
Exhaustible
resources – forests, wildlife, coal
Inexhaustible
resources – air, sunlight, water.
Question 8.
Define
carbonisation.
Answer:
The
slow process of conversion of dead vegetation into coal by nature is called
carbonisation.
Question 9.
What
name is given to the process of heating a substance in absence of air ?
Answer:
Destructive
Distillation.
Question 10.
How
is coke obtained?
Answer:
Coke
is obtained by heating coal in the absence of air.
Question 11.
How
is coal tar formed?
Answer:
When
destructive distillation of coal is done, the vapours which condense in the
water form coal tar.
Question 12.
Why
is petroleum called a fossil fuel?
Answer:
Petroleum
is called a fossil fuel as it is obtained from the bodies of dead organisms.
Question 13.
How
is natural gas formed?
Answer:
Natural
gas is formed below the earth’s surface. It is formed above the petroleum.
2 Mark Questions and Answers
Question
1.
Write
down any four amorphous forms of carbon.
Answer:
The
four amorphous forms of carbons are –
coal, charcoal, coke and lamp black.
Question 2.
Explain
the process of formation of petroleum? Name two places in India where it is
found.
Answer:
Petroleum
is formed by the decomposition of aquatic plants and animal remains.
In
India, petroleum is obtained from oil wells in Assam and Bombay High.
Question 3.
Distinguish
between inexhaustible and exhaustible natural resources.
Answer:
Exhaustible
resources – forests, wildlife, coal
Inexhaustible
resources – air, sunlight, water.
Question 4.
Why
are coal and petroleum known as fossil fuels?
Answer:
Coal
and petroleum are formed from the dead remains of living organisms so are
called fossils fuels.
Question 5.
Give
two characteristics of coal.
Answer:
Coal
is hard and is of black in colour.
Frequently asked MCQs with Answers:
1. Resources present in unlimited quantity in nature and are not likely to be exhausted by human activities are called
(a)
Exhaustible Natural Resources
(b)
Inexhaustible Natural Resources
(c)
Exhaustible Resources
(d)
None of the above
Answer: (b) Inexhaustible Natural Resources
2.
Coal, Petroleum and natural gas are examples of
(a)
Exhaustible Natural Resources
(b)
Inexhaustible Natural Resources
(c)
Expensive Resources
(d)
None of the above
Answer: (a) Exhaustible Natural Resources
3.
Naphthalene balls used to repel moth and insect is derived from
(a)
Petroleum
(b)
Sugar
(c)
Coal tar
(d)
LPG
Answer: (c) Coal tar
4.
CNG is the abbreviated form of
(a)
Combined natural gas
(b)
Compressed Natural Gas
(c)
Confirmed Natural gas
(d)
Condemned Natural gas
Answer: (b) Compressed Natural Gas
5.
The slow process of conversion of dead vegetation into coal is called
(a)
Carbonisation
(b)
fuelification
(c)
Coalification
(d)
None of the above
Answer: (a) Carbonisation
6.
In India petroleum deposit was first found in the state of
(a)
Gujarat
(b)
Maharastra
(c)
Assam
(d)
West Bengal
Answer: (c) Assam
7.
Use of CNG in automobile is better than petrol because it is
(a)
cheaper
(b)
Less polluting
(c)
Cannot be adulterated
(d)
All of the above
Answer: (d) All of the above
8.
To reduce fuel consumption in automobile one should
(a)
Drive very fast to reach early
(b)
Not switch off the engine at traffic lights
(c) Not check tyre pressure regularly
(d)
Ensure proper maintenance of the vehicle
Answer: (d) Ensure proper maintenance of the vehicle
9.
Black gold is actually
(a)
Gold which became black on burning
(b)
Petroleum
(c)
Gold sold in black market
(d)
Diamond
Answer: (b) Petroleum
10.
The earth’s temperature is increasing due to Global warming which is due to
(a)
The Sun giving out more heat
(b)
The Earth slowly moving toward the sun
(c) Increased
use of fossil fuel
(d)
Less duration of winter every year
Answer: (c) Increased use of fossil fuel
11.
The slow process of conversion of dead vegetation into coal is called _____.
(a)
decomposition
(b)
evolution
(c)
carbonification
(d)
carbonisation
Answer: (d) carbonisation
12.
Identify the gas that is generally produced when coal is burnt in the presence
of a lot of air.
(a)
Carbon monoxide
(b)
Sulphur dioxide
(c)
Nitrogen dioxide
(d)
Carbon dioxide
Answer: (d) Carbon dioxide
13.
Coke is used in the manufacture of ______.
(a)
sodium
(b)
mercury
(c)
steel
(d)
potassium
Answer: (c) steel
14.
Identify the substance which is tough, porous and black. It is almost a pure
form of carbon.
(a)
Crude oil
(b)
Coke
(c)
Coal tar
(d)
Coal gas
Answer: (b) Coke
15.
Which of the following is used in metal extraction?
(a)
Coke
(b)
Petroleum
(c)
Coal gas
(d)
Coal tar
Answer: (a) Coke
16.
Which amongst the following is used in the manufacturing of perfumes?
(a)
Coal tar
(b)
Coal gas
(c)
Coke
(d)
Kerosene
Answer: (a) Coal tar
17.
Which of these is an exhaustible resource?
(a)
Air
(b)
Coal
(c)
Water
(d)
Sunlight
Answer: (b) Coal
18.
Which of the following is an example of inexhaustible resources?
(a)
Coal
(b)
Wind
(c)
Petrol
(d)
Diesel
Answer: (b) Wind
19.
In India, which association advises people on saving petrol or diesel while
driving?
(a)
Petroleum Conservation Research Association (PCRA)
(b)
Coal Conservation Research Association (CCRA)
(c)
Eco-driving advice
(d)
Petroleum Conservation Association (PCA)
Answer: (a) Petroleum Conservation Research
Association (PCRA)
20.
Which amongst the following is a petroleum product which can be used in
metalling of roads?
(a)
Coke
(b)
Bitumen
(c)
Coal tar
(d)
Coal gas
Answer: (b) Bitumen
21.
Which of these is used as a solvent for dry cleaning?
(a)
Bitumen
(b)
Paraffin wax
(c)
Petrol
(d)
Kerosene
Answer: (c) Petrol
22.
Many useful substances are obtained from petroleum and natural gas. Select the
correct name given to these substances.
(a)
Petromolecules
(b)
Petrocompound
(c)
Petrochemicals
(d)
Petroproducts
Answer: (c) Petrochemicals
23.
Which of the following is also known as the ‘black gold’?
(a)
CNG
(b)
Natural gas
(c)
Coal
(d)
Petroleum
Answer: (d) Petroleum
24.
Which of these is used for making naphthalene balls?
(a)
Coal tar
(b)
Petroleum
(c)
CNG
(d)
Paraffin
Answer: (a) Coal tar
25.
Petrochemicals are used in the manufacturing of:
(a)
All of these
(b)
Fibres
(c)
Detergents
(d)
Polythene
Answer: (a) All of these
26.
Pavani is very conscious of pollution. So, to reduce the effect of pollution
which fuel should she use for her vehicle?
(a)
Diesel
(b)
Petrol
(c)
LPG
(d)
CNG
Answer: (d) CNG
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