NCERT Solutions Class 8 Science Chapter 3 Coal and Petroleum

Fossil fuel which Coal, oil and gas all comes under and comes the breakdown process of these and their applications along with sustainability forms the primary focus of the chapter in hand. Additionally, it is highly recommended that students do the question and answer exercises in the NCERT Solutions as those are all the basic ideas of the chapter assembled. Students can make use of the coal and petroleum NCERT Solution for Class 8 for the same as they help the student in practicing many questions in a precise manner and the explanation of each question is also provided.

The NCERT Solutions class 8 science chapter 3 coal and petroleum assists the students to understand the otherwise difficult topics more easily. By solving class 8th science chapter 2 coal and petroleum question answer, the students will not only enhance their understanding of the topic learned in class but also help them in increasing their accuracy and preparedness for the examination and thereby building a strong understanding of the different types of fossil fuels and their significance.

1.0Download NCERT Solutions Class 8 Science Chapter 3 PDF

2.0What Will Students Learn in Chapter 3: Coal and Petroleum?

In this chapter titled 3. Coal and Petroleum, students will focus on learning the following key concepts.

• Fossil fuels: their definition, how they are generated, and their significance.
• Coal: how it is formed and its different types and how it is used in everyday life.
• Petroleum: how petroleum is processed, petroleum products and their uses.
• Natural Gas: Its applications and role as a renewable energy source.
• Waste of Fossil Fuels: The reason why these resources are to be saved for the coming years.
• Effects on the Environment: The impact of excessive use and waste management of fossil fuel energy.
• Need for searching other energy sources for continued existence and development.

3.0NCERT Questions with Solutions Class 8 Science Chapter 3 - Detailed Solutions

• What are the advantages of using CNG and LPG as fuels? Sol. The advantages of using CNG and LPG as fuel are: (i) They are non-polluting fuels for vehicles. (ii) They can be used for power generation. (iii) They can be used directly for burning in homes and factories.
• Name the petroleum product used for surfacing of roads. Sol. A petroleum product 'Bitumen' is used for surfacing of roads.
• Describe how coal is formed from dead vegetation. What is the process called? Sol. About 300 million years ago the earth had dense forests in low lying wetland areas. Due to natural process, like flooding, these forests got burried under the soil. As more soil deposit 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 to coal. As coal contains mainly carbon, the slow process of conversion of dead vegetation into coal is called carbonisation.
• Fill in the blanks : (a) Fossil fuels are and (b) Process of separation of different constituents from petroleum is called (c) Least polluting fuel for vehicle is ........... Sol. (a) Coal, petroleum, natural gas. (b) Refining (c) CNG.
• 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 almost pure form of carbon. (d) Coal tar is a mixture of various substances. (e) Kerosene is not a fossil fuel. Sol. (a) False (b) False (c) True (d) True (e) False
• Explain, why fossil fuels are exhaustible natural resources? Sol. Fossil fuels are limited in nature and is used by human activities so called as exhaustible natural resources.
• Describe characteristics and uses of coke. Sol. It is a tough, porous and black substance. It is almost pure form of carbon. Coke is obtained by heating soft coal in the absence or little supply of air. It is used in the manufacture of steel and in the extraction of many metals.
• Explain the process of formation of petroleum. Sol. Petroleum occurs deep down in the earth between layers of non-porous rocks. Crude oil/petroleum is formed by the decomposition of animal and plant remains over millions of years inside the earth. Natural gas occurs above the petroleum oil trapped under the rocks.
• 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:

Sol.

EXERCISE-01

Multiple choice questions

• Coal and petroleum are (1) inexhaustible resources (2) fossil fuels (3) renewable resources (4) all of these
• Producer gas contains (1) nitrogen and carbon monoxide (2) hydrogen and nitrogen (3) nitrogen and carbon dioxide (4) hydrogen and carbon dioxide
• Which gas is produced when coal burns in air? (1) Carbon dioxide (2) Oxygen (3) Nitrogen (4) Hydrogen
• Which one is an ideal fuel? (1) Natural gas (2) Coal (3) Kerosene (4) Petrol
• Fossil fuels are (1) wood and coke (2) wood and anthracite (3) coal and petroleum (4) charcoal and coal tar
• Formation of coal from plant matter is called (1) destructive distillation (2) carbonisation (3) both (1) and (2) (4) none of these
• Oldest form of fossil coal is (1) lignite (2) anthracite (3) coke (4) charcoal
• Which one is a house hold variety of coal? (1) Peat (2) Bituminous (3) Lignite (4) Anthracite
• Maximum carbon containing coal is (1) peat (2) lignite (3) bituminous (4) anthracite
• Which of the following names represents the foul smelling, black, thick, viscous liquid obtained from destructive distillation of coal? (1) Coke (2) Coal tar (3) Coal gas (4) None of these
• Heating of coal in the absence of air is called (1) destructive distillation (2) carbonisation (3) both (1) and (2) (4) none of these
• Hydrocarbons contain (1) carbon and hydrogen (2) carbon and oxygen (3) carbon and nitrogen (4) carbon and carbon dioxide
• The combustion of hydrocarbon gives (1) water and carbon dioxide as product. (2) water and methane as product. (3) methane and propane as product. (4) none of these
• Which of the following gases is supplied in LPG (Liquefied Petroleum Gas) cylinders for domestic use? (1) Methane and Propane (2) Methane and Ethane (3) Ethane and Butane (4) Propane and Butane
• Petroleum is refined by (1) simple distillation (2) fractional distillation (3) destructive distillation (4) none of these
• Power alcohol is (1) alcohol mixed with petrol (2) alcohol mixed with kerosene (3) alcohol mixed with sulphur (4) alcohol mixed with ethane
• The oldest oil refinery in India is located at (1) Mathura (2) Digboi (3) Haldia (4) Kochi
• The process of separating useful fractions from petroleum is called (1) refining (2) evaporation (3) both (1) and (2) (4) none of these
• Which one is used for making shoe polishes? (1) Paraffin wax (2) Petrol (3) Diesel (4) Lubricating oil
• Which one of the following is not a petroleum product? (1) Kerosene (2) Gasoline (3) Asphalt (4) Bees wax
• Natural gas mainly contains (1) propane (2) butane (3) methane (4) ethane
• CNG stands for (1) conventional natural gas (2) coal and natural gas (3) compressed natural gas (4) commercial natural gas
• Which of the following is used as a household fuel? (1) Gasoline (2) Paraffin wax (3) Kerosene (4) All of these
• Which of the following is not true for natural gas? (1) It is generally found with petroleum deposits. (2) It can be liquefied under pressure. (3) It is a rich source of hydrogen. (4) It has a low calorific value.
• The substance added to detect the leakage of LPG is (1) methyl mercaptan (2) ethyl mercaptan (3) both (1) and (2) (4) none of these

True or False

• Water gas is a mixture of carbon dioxide and nitrogen.
• Kerosene is not a by product of fossil fuel.
• Excessive use of coal for energy improves the quality of air.
• Coal tar is black, thick, liquid with unpleasant smell.
• Coal tar is a mixture of various substances.
• Coke is almost pure from of carbon.
• Coal is mainly used to produce electricity.
• Anthracite has maximum carbon content.
• Coke and coal are two names for the same substance.
• Petroleum is called black gold.
• The petroleum pumped out from oil wells can be used as it is.
• Petroleum is a complex mixture of many organic compounds.
• Natural gas mainly contains methane.
• CNG is more polluting fuel than petrol.
• ONGC deals with exploration of petroleum in India.

Fill in the blanks

• Minerals, forest, wildlife are natural resources.
• Producer gas is a mixture of and _.
• are inexhaustible natural resources.
• Fossil fuels are resources.
• is called black gold.
• The slow process of conversion of dead vegetation into coal is called .
• The process by which the carbon content of coal increases is called .
• is used as domestic and industrial fuel.
• Wood is converted into coal by the process of .
• is the best variety of coal.
• The process of heating coal in the absence of air is called .
• Coke is used in the extraction of _.
• Process of separation of different constituents from petroleum is called .
• Petroleum or crude oil pumped out from is not pure.
• The first oil well was dug in India at in the year _.
• is used for running light vehicles.
• CNG (natural gas) is fuel.
• A marked rise in global standards of living is directly traceable to wide spread use of _.
• A worldwide increase in temperature is called warming.
• contains 98% carbon.

Match the column

Crossword puzzle

Across

• It is used to pave roads.
• It is the main content of natural gas.
• It was used for lighting houses, factories and streets in Mumbai.
• It is known as soft coal.
• The process of heating coal in the absence of air is called.

Down

• A liquid product formed on destructive distillation of coal.
• A gas with highest calorific value.
• Petroleum is also known as.
• Crude oil has foul smell if it contains X . X is a non-metal.
• It is used as a dry-cleaning fluid.

ANSWER KEY

Multiple choice questions

True or False

• False
• False
• False
• True
• True
• True
• True
• True
• False
• True
• False
• True
• True
• False
• True

Fill in the blanks

• exhaustible
• CO, N 2
• Sunlight and air
• exhaustible
• Petroleum
• carbonisation
• carbonisation
• Coal
• Carbonisation
• Anthracite
• destructive distillation
• metals
• refining
• oil wells
• Assam, 1867
• Petrol
• fossil
• Fossil fuels
• global
• Coke

Match the column

• (1) $\to$ (iii), (2) $\to$ (iv), (3) $\to$ (v), (4) $\to$ (ii), (5) $\to$ (i)
• (1) $\to$ (ii), (2) $\to$ (i), (3) $\to$ (iv), (4) $\to$ (iii)
• (1) $\to$ (iii), (2) $\to$ (iv), (3) $\to$ (ii), (4) $\to$ (i)

Crossword puzzle

EXERCISE-02

Very short answer type questions

• Name two fossil fuels.
• Name four varieties of coal.
• Which process is used to separate the components of petroleum?
• Name the petroleum product used for surfacing of roads.
• What is the source of natural gas? Short answer type questions
• Differentiate between inexhaustible and exhaustible natural resources.
• Write a short note on the formation of coal.
• State two important uses of coal.
• Give the uses of the following (i) Coke (ii) Coal tar (iii) Coal gas
• How is petroleum formed in nature?
• Why is petroleum called black gold?
• Give the uses of the following (i) Kerosene (ii) Lubricating oil (iii) Paraffin wax (iv) Diesel
• Comment on the uses of natural gas.
• What is the use of LPG.? How do you detect its presence?
• Write two ways to conserve fossil fuels.

Long answer type questions

• What is coal gas? Describe the use of coal gas.
• Describe the characteristics and uses of coke.
• Describe the process of refining of petroleum with the help of diagram.
• What are the constituents and uses of petroleum?
• What is natural gas? Write the use of natural gas

Exercise - 01 Solutions

Multiple choice questions

• Option (2) Coal and Petroleum were formed from the dead remains of living organisms (fossils).
• Option (1) When Air is passed over red hot coke then producer gas $\left(\mathrm{CO}+{\mathrm{N}}_2\right)$ is formed.
• Option (1) The combustion of coal gives energy and releases carbon dioxide gas.
• Option (1) Natural gas is an ideal fuel and has a high calorific value.
• Option (3) Coal and Petroleum were formed from the dead remains of living organism (fossil fuels).
• Option (2) The formation of coal occurs over millions of years via a process known as carbonisation.
• Option (2) Last formed coal is Anthracite.
• Option (2) Bituminous coal is used as house - hold variety of coal.
• Option (4) Anthracite is the hardest coal containing maximum carbon.
• Option (2) Coal tar is a mixture of different carbon compounds. It is a thick, black, liquid with unpleasant smell, Obtained from destructive distillation of coal.
• Option (1) The process of heating coal in the absence of air is called the destructive distillation of coal.
• Option (1) Hydrocarbons are those substances which are made of carbon and hydrogen.
• Option (1) Hydrocarbons burns in air forming, Carbon dioxide and water.
• Option (4) Propane and Butane gases are supplied in LPG cylinders for domestic use.
• Option (2) Petroleum refining is done by a process called Fractional distillation.
• Option (1) Mixture of $80\%$ petrol with 20% Alcohol is known as power alcohol.
• Option (2) The oldest oil refinery in India is located at Digboi (Assam).
• Option (1) The process of separating the various components of petroleum from one another is known as the refining of Petroleum.
• Option (1) Paraffin wax is used for making shoe polishes.
• Option (4) Bees wax is not a petroleum product. It is not obtained from petroleum.
• Option (3) Natural gas consist mainly of Methane (85%), ethane (10%), Propane (3%) and butane (2%).
• Option (3) Full from of CNG is compressed natural gas.
• Option (3) Kerosene is used as a household fuel.
• Option (4) It has a low calorific value Exp. Natural gas has a high calorific value.
• Option (2) The substance added to detect the leakage of LPG is Ethyl mercaptan.

True or False

• False Water gas is a mixture of carbon Monoxide and hydrogen $\left(\mathrm{CO}+{\mathrm{H}}_2\right)$.
• True Kerosene is obtained fractional distillation of petroleum so it is a fossil fuel.
• False Excessive use of coal for energy pollutes air.
• True Coal tar is black, thick, liquid with unpleasant smell.
• True Coal tar is mixture of various substances. Such as dyes pains explosive drugs etc.
• True Coke is almost pure from of carbon.
• True Coal is mainly used to produce electricity.
• True Anthracite has maximum carbon content.
• False Coke and Coal are two different substance.
• True Petroleum is called black gold.
• False The Petroleum pumped out from oil wells cannot be used as it is.
• True Petroleum is a complex mixture of many organic compounds.
• True Natural gas mainly contain Methane.
• False CNG is less polluting fuel than Petrol.
• True ONGC deals with exploration of petroleum in India. (ONGC $\Rightarrow$ Oil and Natural Gas corporation).

Exercise - 02 Solutions

Very short answer type questions

• Two examples of fossil fuels are coal and natural gas.
• (a) Peat (b) Lignite (c) Bituminous coal (d) Anthracite coal These are four varieties of coal.
• In Refining of petroleum, a process is used named Fractional distillation.
• Bitumen is petroleum product which is used for surfacing of roads.
• Natural gas is generally found trapped between impervious rocks sometimes along with petroleum and sometimes without petroleum.

Short answer type questions

• Inexhaustible natural resources :- These sources are present in unlimited quantity in nature and are not likely to be exhausted by human activities. Eg :- sunlight, air etc. Exhaustible natural resources :- The amount of these resources in nature is limited, they can be exhausted by human activities. Examples :- Forests, Coal, Petroleum, Minerals, Wild life, natural gas etc.
• Formation of Coal :- About 300 million years ago the earth had dense forests in low lying wetland areas. Due to natural process like flooding, earthquakes and volcanoes, these forests got buried under the soil. 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 to coal, this processs is known as carbonisation.
• Uses of Coal :- (i) Coal is used primarily as an energy source either for heat or electricity. It is used in railway engines to produce steam to run engines. (ii) Bituminous coal is also used to produce coke for making steel and other industrial process heating.
• (i) Uses of Coke: - Coke is largely employed as a reducing agent in the extraction of metals from their ores. it is also used in making fuel gases like water gas $\left(\mathrm{CO}+{\mathrm{H}}_2\right)$ and producer gas ( $\mathrm{CO}+{\mathrm{N}}_2$ ) (ii) Uses of Coal tar :- Many Chemical substances are obtained from coal tar which are used in the preparation of dyes, explosives, paints, synthetic fibres, drugs and Pesticides. (iii) Uses of Coal gas :- Coal gas is an excellent fuel. It has high Calorific value. It is used for lighting houses, factories and streets, main use in factories as fuel.
• Formation of Petroleum in nature :- Tiny sea plants and animals died and were buried on the ocean floor. Over the time they were covered by layers of silt and sand. Over millions of years the remains were buried deeper and deeper. The enormous heat and pressure turned them into petroleum oil and natural gas. Petroleum occurs at a moderate depth (500 to 2000 $m$ ) between the two layers of impervious rocks.
• Many useful substances are obtained from petroleum which can be used for the manufacture of detergents, fibres (Polyester, nylon, acrylic etc.) Polyethene and many other plastics. Due to its great commercial importance petroleum is also called black gold.
• (i) Used of Kerosene $\to$ Kerosene is used as house hold fuel, illuminant aviation fuel (Purified form). (ii) Uses of lubricating oil :- Lubricating oil used as a lubrication to reduce friction in metallic parts. (iii) Uses of Paraffix wax :- Paraffin wax is used in making Candles, water proof fabrics, matchsticks, cosmetics, grease, vaseline & Ointments. (iv) Uses of Diesel :- Diesel is used as fuel for diesel cars, trucks, bus.
• Uses of Natural gas (i) As a fuel :- It has a very high Calorific value of $55\mathrm{KJ}/\mathrm{gm}$ and used as compressed natural gas (CNG). It is used for power generation in automobiles and as fuel for car and bus. (ii) It is use as a source of hydrogen and carbon.

• Use of LPG $\to$ Liquified petroleum gas (LPG) is used as a domestic fuel. . It is used in cooking food at home and also used in automobiles. $\Rightarrow$ LPG doesn't have any characterstic smell to detect its leakage. A foul-smelling substance ethyl mercaptan $\left({\mathrm{C}}_2{\mathrm{H}}_5\mathrm{SH}\right)$ is added to it.
• Two ways of conserving fossil fuels. (a) Drive at a constant and moderate speed as far as possible. Driving at high speed or slow speed wastes a lot of fuel. (b) Switch off the engine if you have to wait at traffic light or for any other reason.

Long answer type questions

• Coal Gas :- Coal gas is mainly a mixture of hydrogen, methane and carbon monoxide. The gas present in coal gas are combustible and hence it is an excellent fuel. It has high calorific value. It was used for lighting houses, factories and streets in mumbai, till 1950. It was also used for cooking earlier.
• Coke :- contains $98\%$ carbon. It is porous, tough, black and the purest form of coal, like charcoal. It is a good fuel and burns without smoke. It is largely employed as a reducing agent in extraction of metals from their ores. It is also used in making fuel gases like water gas and producer gas. When steam is passed over red hot coke then water gas $\left(\mathrm{CO}+{\mathrm{H}}_2\right)$ is formed which is used as a fuel in industries.

• When Air is passed over red hot coke then producer gas ( $\mathrm{CO}+{\mathrm{N}}_2$ ) is formed, which is also used as a fuel in industries.
• Refining of Petroleum: - Petroleum is a mixture of several hydrocarbons. The process of separating the various components of petroleum from one another is known as the refining of petroleum. This is done by a process called fractional distillation which is based on the fact that the different components of petroleum have distinctly different boiling points. In fractional distillation crude petroleum is heated to a temperature of $400^{\circ }\mathrm{C}$ or slightly above in a furnace.

• Fractional distillation of crude oil
• Constituents of Petroleum: - These are some constituents of PetroleumPetroleum ether, Gasoline or Petrol, Kerosene, Gas oil and diesel oil, Lubricating oils, grease, vaseline, Paraffin wax, Pitch and tar, Petroleum coke and Bitumen. Uses of Petroleum- (i) Petroleum products are used as fuels. (ii) Lubricating oils, and Vaseline are used as lubricants. (iii) Paraffin wax, products of Petroleum is used for manufacturing candles, polishes, waxed paper, water proofing etc. (iv) Some of the by-products of Petroleum after Purification are used in the preparation of medicines, ointments face creams and cosmetics.
• Natural gas: - Natural gas was formed millions of years ago along with petroleum when microscopic sea plants & animals died & got buried under the sand & mud. These plants & animals under anaeobic conditions changed to gas. Composition: - 85% Methane gas, 10% ethane gas, $3\%$ Propane and 2% butane. When it is compressed at high pressure then it is called CNG (Compressed natural gas) Uses: (i) As a fuel - It has a very high calorific value of $55\mathrm{KJ}/\mathrm{g}$. (ii) As a source of hydrogen & Carbon.