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Coal And Petroleum

Class 8th Science NCERT Exemplar Solution
Multiple Choice Questions
  1. Various materials which are obtained from nature are called natural resources. Which of…
  2. Air is a natural resource and cannot be exhausted by human activities. It is known as…
  3. Which of the following is a pair of exhaustible natural resources.A. coal and soil B. air…
  4. Coal is processed in industries to get some useful products. Which of the following is not…
  5. Exhaustible natural resources are:A. unlimited in quantity. B. not dependent on nature. C.…
  6. Fossil fuels are obtained from:A. remains of non-living materials. B. dead remains of…
  7. Coal is formed from the remains ofA. vegetation only B. animals only C. both vegetation…
  8. Which substance is formed by the carbonization of dead vegetation?A. coal B. coke C. coal…
  9. Naphthalene balls are obtained from coal tar and are used asA. mosquito repellant B. honey…
  10. Which of the following is not a constituent of petroleum?A. paraffin wax B. lubricating…
  11. Petroleum was formed from organisms:A. living on the land B. living on the plants C.…
  12. Choose the correct statement from the following:A. It is difficult to transport natural…
Very Short Answer Type
  1. You are provided with a mixture of petroleum and water. Can you suggest a method to…
  2. What does CNG stand for and why is it considered to be a better fuel than petrol?…
  3. Name the petroleum product used as fuel for stoves, lamps and jet aircrafts.…
  4. Fill in the blanks in the following sentences. (a) Coal is one of the ________ used to…
  5. The underlined words in the following sentences have been jumbled up. Write them in their…
  6. Fill in the blanks. (a) The slow process of conversion of dead vegetation into coal is…
  7. Write True/False against the following statements. (a) Oxygen in air is an exhaustible…
Short Answer Type
  1. Sunlight and air are inexhaustible natural resources. Comment.
  2. Some natural resources are given in a box. Classify them into the exhaustible and…
  3. Write two important uses of coke.
  4. Write the characteristics and some important uses of coal.
  5. Look at Fig. 5.1 where petroleum and natural gas deposits are shown. Why do we find oil…
  6. Fill in the blanks and complete the story. About 300 million years ago the earth had dense…
  7. Match the items given in Column I with the items of Column II.
Long Answer Type
  1. Name the products obtained and their uses when coal is processed in industry.…
  2. We say fossil fuels will last only for a few hundred years. Comment.…
  3. We read in newspapers that burning of fuels is a major cause of global warming. Explain…
  4. While driving what are the tips we must follow to save petrol/ diesel/natural gas?…
  5. Imagine that all the exhaustible natural resources are exhausted by human activities. Do…
  6. Why petrol is exhaustible natural resource, whereas sunlight is not? Explain.…
  7. Write some important uses of the various constituents of petroleum.…
  8. Coal reserves are said to be enough to last for another hundred years. Do you think we…
  9. What steps would you suggest for the judicious use of fossil fuels?…
  10. Complete the crossword Fig. 5.2 with the help of the clues: Across 1. Fuels obtained from…

Multiple Choice Questions
Question 1.

Various materials which are obtained from nature are called natural resources. Which of the following is not a natural resource?
A. minerals

B. water

C. soil

D. plastic


Answer:

Plastic is a man-made material and it is not obtained from nature whereas minerals, water, soil are obtained from nature.


Question 2.

Air is a natural resource and cannot be exhausted by human activities. It is known as inexhaustible natural resource. Which of the following is another inexhaustible natural resource?
A. coal

B. petroleum

C. sun-light

D. minerals


Answer:

Sunlight is an example of inexhaustible natural resource as it is present in unlimited quantity and cannot be exhausted due to human activities.


Question 3.

Which of the following is a pair of exhaustible natural resources.
A. coal and soil

B. air and sun-light

C. water and petroleum

D. wild life and minerals


Answer:

Wildlife and minerals are exhaustible natural resources as they are present in limited quantity in nature and can be exhausted due to human activities.


Question 4.

Coal is processed in industries to get some useful products. Which of the following is not obtained from coal?
A. coke

B. coal tar

C. coal gas

D. CNG


Answer:

When natural gas is compressed applying pressure it is called CNG. Whereas coke, coal tar, coal gas etc. are the products obtained from coal.


Question 5.

Exhaustible natural resources are:
A. unlimited in quantity.

B. not dependent on nature.

C. limited in quantity.

D. not exhausted by human activities.


Answer:

Exhaustible natural resources are limited in quantity and can be exhausted due to human activities.


Question 6.

Fossil fuels are obtained from:
A. remains of non-living materials.

B. dead remains of birds only.

C. dead remains of insects only.

D. dead remains of living organisms.


Answer:

Fossil fuels are formed from dead remains of living organisms like plants, animals etc under high pressure, high temperature and absence of air.


Question 7.

Coal is formed from the remains of
A. vegetation only

B. animals only

C. both vegetation and animals

D. neither vegetation nor animals


Answer:

The dead plants buried under the surface of earth under high pressure, temperature and in absence of air slowly convert into coal.


Question 8.

Which substance is formed by the carbonization of dead vegetation?
A. coal

B. coke

C. coal gas

D. coal tar


Answer:

Coal is formed from dead plants buried deep under earth’s surface by carbonization process.


Question 9.

Naphthalene balls are obtained from coal tar and are used as
A. mosquito repellant

B. honey bee repellant

C. moth repellant

D. snake repellant


Answer:

One of the useful compounds obtained from coal tar is naphthalene and due to its strong smell it acts as a moth repellant. It is kept in cupboards containing clothes, books etc to prevent damage due to attack of moths.


Question 10.

Which of the following is not a constituent of petroleum?
A. paraffin wax

B. lubricating oil

C. petrol

D. coke


Answer:

Coke is a product obtained from coal whereas the rest are obtained by refining of petroleum through fractional distillation.


Question 11.

Petroleum was formed from organisms:
A. living on the land

B. living on the plants

C. living in the sea

D. living on the rocks


Answer:

Petroleum is obtained from dead remains of sea animals which settled at the bottom of sea and under high pressure, temperature and in absence of air converts into petroleum.


Question 12.

Choose the correct statement from the following:
A. It is difficult to transport natural gas through pipes.

B. The disadvantage of natural gas is that it can not be used directly for burning in homes.

C. Natural gas is stored under high pressure as compressed natural gas.

D. Natural gas cannot be used for power generation.


Answer:

When natural gas is compressed under high pressure it is called CNG which is a clean fuel used in vehicles.



Very Short Answer Type
Question 1.

You are provided with a mixture of petroleum and water. Can you suggest a method to separate the two?


Answer:

Decantation process is used to separate a mixture of petroleum and water. Petroleum being lighter will form the top layer above water layer and can be poured to another container carefully without disturbing the bottom layer.



Question 2.

What does CNG stand for and why is it considered to be a better fuel than petrol?


Answer:

CNG stands for Compressed Natural Gas. It is considered as a better fuel than petrol because it is a clean fuel and does not produce smoke, there is no residues left after burning, there is less chance of air pollution, it is easy to transport through pipelines and produce a lot of heat energy when burnt.



Question 3.

Name the petroleum product used as fuel for stoves, lamps and jet aircrafts.


Answer:

Kerosene is the petroleum product used as fuel for stoves, lamps and jet aircrafts. It is obtained through refining of petroleum by fractional distillation.



Question 4.

Fill in the blanks in the following sentences.

(a) Coal is one of the ________ used to cook food.

(b) When heated in air, coal burns and produces mainly ________ gas.

(c) Coal tar is a black, thick ________ with an ________ smell.

(d) Petroleum, ________ and ________ are fossil fuels.

(e) Forests and coal are ________ natural resources.


Answer:

a) Fuels


Coal produces heat energy when burnt so it can be used as a good fuel to cook food.


b) Carbon dioxide


Coal is a form of carbon so when it burns in air, it reacts with oxygen to form carbon dioxide gas.


c) liquid, unpleasant


Coal tar is one of the products of coal which is a black, thick fluid having unpleasant smell which is used for metalling roads.


d) Coal, natural gas


They are fossil fuels as they are obtained from dead remains of plants, animals.


e) Exhaustible


They are present in limited quantity in nature and can be exhausted by human activities.



Question 5.

The underlined words in the following sentences have been jumbled up. Write them in their correct form.

(a) Loca is obtained from mines.

(b) Umpetlore is a fossil fuel.

(c) Rineryfe is a place where various fractions of petroleum are separated.

(d) Keenrose is a fuel used in jet crafts.

(e) Nutsgilh is an example of inexhaustible natural resources.


Answer:

a) Coal


Coal is formed deep under the surface of earth which is obtained by digging them. The places where coal are found are known as coal mines.


b) Petroleum


Petroleum is formed from dead remains of plants and animals and hence are known as fossil fuels.


c) Refinery


The various products are obtained from petroleum by refining process in a refinery. The products are obtained by fractional distillation process.


d) Kerosene


Kerosene is a product obtained by refining of petroleum which is used as a fuel in jet crafts, stoves, lamps etc.


e) Sunlight


Sunlight is available in unlimited quantity in nature and cannot be exhausted by human activities. So it is an inexhaustible natural resource.



Question 6.

Fill in the blanks.

(a) The slow process of conversion of dead vegetation into coal is called__________.

(b) Coal and petroleum are formed from the dead remains of organisms and are known as __________.

(c) The black thick liquid with __________ smell is known as coal tar.

(d) During the processing of coal to get coke, coal tar and__________ are also obtained.

(e) The process of separating the various constituents of petroleum is known as __________.

(f) Excessive burning of fossil fuels is a major cause of __________.


Answer:

a) Carbonization


Carbonization is the process of slow conversion of dead plants into coal under high pressure, temperature and in absence of air.


b) Fossil fuels


Coal and petroleum are known as fossil fuels as they are obtained from dead remains of plants and animals.


c) Unpleasant


Coal tar is a product of coal which is a thick black liquid with unpleasant smell used for road surfacing.


d) Coal gas


Coal gas is a product of coal which is a gaseous fuel obtained during processing of coal to get coke.


e) Refining


Refining is the process of separating various components of petroleum in a refinery and this method employs fractional distillation technique.


f) Air pollution


Fossil fuels mainly contain carbon and burning of these fuels release carbon dioxide gas which causes air pollution.



Question 7.

Write True/False against the following statements.

(a) Oxygen in air is an exhaustible natural resource.

(b) Resources which are present in unlimited quantity in nature are called exhaustible natural resources.

(c) Wildlife is an exhaustible natural resource.

(d) Under high temperature and pressure, dead plants get slowly converted to coal.

(e) CNG is less polluting fuel than petrol and diesel.


Answer:

(a) False,

Oxygen in air is an inexhaustible natural resource as it is present in unlimited quantity in nature and cannot be exhausted by human activities.


(b) False


Inexhaustible natural resources are present in unlimited quantity in nature and cannot be exhausted by human activities.


(c) True


They are limited in number and can be exhausted as a result of human activities so it is a exhaustible natural resource.


(d) True


The dead remains of plants buried under earth’s surface under high pressure and temperature and in absence of air slowly convert into coal.


(e) True.


CNG is compressed natural gas formed under high pressure and when it burns it does not produce smoke. After burning it does not leave any solid residues behind so it is a clean fuel and is less polluting than petrol or diesel.




Short Answer Type
Question 1.

Sunlight and air are inexhaustible natural resources. Comment.


Answer:

Sunlight and air are present in unlimited quantity in nature and cannot be exhausted due to human activities. So they are called inexhaustible natural resources.



Question 2.

Some natural resources are given in a box. Classify them into the exhaustible and inexhaustible natural resources.

air, coal, natural gas, sunlight, petroleum, minerals, forests, oxygen.


Answer:

Exhaustible resources are coal, natural gas, petroleum, minerals, forests. They are present in limited quantity and are exhausted by human activities.

Inexhaustible resources are air, sunlight, oxygen. They are present in unlimited quantity and cannot be exhausted by human activities.



Question 3.

Write two important uses of coke.


Answer:

Two important uses of coke are it is used as a reducing agent in the extraction of metals like iron, zinc etc. It is used in the manufacture of steel.



Question 4.

Write the characteristics and some important uses of coal.


Answer:

Some characteristics of coal is it is black in colour and hard. Some important uses of coal are

a) It is used as a fuel in thermal power plants to produce electricity.


b) Used as a fuel for cooking.


c) Used to obtain products like coal tar, coke, coal gas.


d) Used as a fuel in many industries.



Question 5.

Look at Fig. 5.1 where petroleum and natural gas deposits are shown. Why do we find oil layer above water layer?



Answer:

Oil layer is above water layer as it is lighter than water so it will float above the water layer.



Question 6.

Fill in the blanks and complete the story.

About 300 million years ago the earth had dense ________ in low lying wetland areas. Due to natural processes, like ______, these forests got burried under the ________. As more ________ deposited over them, they were compressed. The ________ also rose as they sank deeper and deeper. Under high ________ and high ________, dead plants got slowly converted into coal.


Answer:

About 300 million years ago the earth had dense Forests in low lying wetland areas. Due to natural processes, like Floods, earthquakes, volcanoes, these forests got burried under the Earth’s surface. As more Soil deposited over them, they were compressed. The Temperature also rose as they sank deeper and deeper. Under high Pressure and high Temperature, dead plants got slowly converted into coal.


The above passage gives detail about the process of formation of coal. Before 300 million years, dense forests due to natural phenomenon like earthquakes, volcanic eruptions, floods etc. get buried under the surface of the earth. Soil gets deposits over them and they get compressed. As they are pressed more deep into earth’s surface the temperature increases. Due to high temperature and pressure, they slowly get converted into coal by carbonization process.



Question 7.

Match the items given in Column I with the items of Column II.



Answer:

a – iii


Bitumen is a petroleum product used for surfacing of roads.


b – iv


Natural gas when compressed under high pressure, it is called CNG.


c – i


Petroleum is called black gold because when it is extracted from earth’s surface it is black in colour and on refining we obtain many useful products which have high commercial values.


d – ii


Paraffin wax is obtained from the refining of petroleum and is used for making candles, vaselines, ointments etc.




Long Answer Type
Question 1.

Name the products obtained and their uses when coal is processed in industry.


Answer:

When coal is processed in industry various products like coal tar, coal gas and coke are obtained.

Uses of coke are as a fuel, in the manufacture of steel and as a reducing agent in the extraction of metals like iron, zinc etc.


Coal tar is used for metalling roads, various compounds like phenol, toluene, benzene, naphthalene, aniline are present in it. It is used as a starting material in various industries like drugs, explosives, synthetic dyes, perfumes, plastics etc.


Coal gas is used as a fuel in many industries and for lightning purposes.



Question 2.

We say fossil fuels will last only for a few hundred years. Comment.


Answer:

Fossil fuels are formed under earth’s surface from dead remains of plants and animals. It is a very slow process and it takes millions of years to be formed. If they will be consumed at a very faster rate then the rate at which they are formed, they soon will get exhausted. Our future generations will not be able to make use of them as it takes millions of years to be formed. So it is said that fossil fuels will last only for a few hundred years.



Question 3.

We read in newspapers that burning of fuels is a major cause of global warming. Explain why.


Answer:

Fossil fuels are carbonaceous compounds which when burning in air releases carbon dioxide gas, the main gas which causes global warming. This gas traps heat rays of the sun inside the surface of the earth and thus increases the temperature. This is called Greenhouse effect and consequence of this effect is global warming. The temperature of the earth will rise gradually.



Question 4.

While driving what are the tips we must follow to save petrol/ diesel/natural gas?


Answer:

The tips to follow are:

a) Drive at constant or moderate speed.


b) Checking pressure of tyres at regular intervals.


c) Regular servicing and maintenance of vehicles.


d) Switch off engines of vehicles at traffic signals.



Question 5.

Imagine that all the exhaustible natural resources are exhausted by human activities. Do you think survival of living beings would be possible.? If yes, why?, If not, why not?


Answer:

No, survival of living beings would not be possible. Exhaustible natural resources include fossil fuels, wildlife, forests, minerals etc. which has a great importance in our life. If they will be exhausted the ecological balance cannot be maintained. For example- Forests which is an important natural resource that causes rainfall, prevents soil erosion, floods, provide oxygen, valuable products etc. We cannot imagine our life without them. Similarly, if wildlife gets exhausted the balance of our nature will get disturbed. Fossil fuels are an important source of energy for us. Without them, we have to opt for alternative sources of energy which is not easy and expensive.



Question 6.

Why petrol is exhaustible natural resource, whereas sunlight is not? Explain.


Answer:

Petrol is a fossil fuel which is present in limited quantity in nature and can be exhausted by human activities but sunlight is present in unlimited quantity in nature and cannot be exhausted by human activities. So petrol is exhaustible natural resource, whereas sunlight is not.



Question 7.

Write some important uses of the various constituents of petroleum.


Answer:

Some important uses of various constituents of petroleum are as under:



Question 8.

Coal reserves are said to be enough to last for another hundred years. Do you think we need to worry in such case? Why or why not?


Answer:

Yes, this is a case of concern as coal is one of the important fossil fuels and it takes millions of years to be formed. This is also an exhaustible natural resource so we have to use it judiciously so that it can be available for our future generations as well. If we will go on consuming it at a faster rate then it might get exhausted very soon as the rate at which it is formed is very slow.



Question 9.

What steps would you suggest for the judicious use of fossil fuels?


Answer:

The steps for judicious use of fossil fuels are:

a) Use of alternative sources of energy like solar energy.


b) We can opt for car pooling.


c) We can use public transport.


d) We can either walk or use the cycle to travel short distances.


e) We should handle these fuels efficiently during transport minimizing their loss.



Question 10.

Complete the crossword Fig. 5.2 with the help of the clues:



Across

1. Fuels obtained from dead remains of living organisms. (6,5)

2. A process by which the various constituents of petroleum are separated. (8)

3. A porous black substance obtained from coal. (4)

4. Another name for motor fuel. (6)

Down

5. The substance obtained by carbonization. (4)

6. Fuel for heavy motor vehicles. (6)

7. A petroleum product used for road surfacing. (7)

8. Dead remains of sea animals got converted into it. (9)


Answer:

1) Fossil fuels


Fossil fuels are obtained from dead remains of living organisms i.e. plants or animals. Examples are coal, petroleum, natural gas etc.


2) Refining


The various constituents of petroleum are separated by refining process in a refinery. This method employs fractional distillation technique. Petrol, diesel, kerosene, paraffin wax, LPG etc. are obtained by this process.


3) Coke


Coke is a product obtained by destructive distillation of coal. It is a tough, porous and black solid substance used as a fuel.


4) Petrol


Petrol is commonly used as a fuel in vehicles which is known as motor fuel.


5) Coal


Coal is obtained by slow decomposition of dead remains of plants under earth’s surface in absence of air under high pressure and temperature. This process is called carbonization.


6) Diesel


Diesel is used as a fuel for heavy motor vehicles. It is one of the product obtained from refining of petroleum.


7) Bitumen


Bitumen is obtained by refining of petroleum which is used for metalling the roads.


8) Petroleum


Petroleum is obtained from dead remains of sea animals which settled down in the bottom of sea and get covered with sand, mud, clay. Due to high pressure, temperature and in absence of air they slowly gets converted into petroleum.