Ncert Exemplar Solutions Class 8 Science Coal and Petroleum

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Ncert Exemplar Solutions Class 8 Science Coal and Petroleum

Welcome to NCTB Solutions. Here with this post we are going to help 8th class students for the Solutions of NCERT Exemplar Class 8 Science Book, Unit 5, Coal and Petroleum. Here students can easily find step by step solutions of all the problems for Coal and Petroleum, Also here our Science teacher’s are solved all the questions with easily understandable language with proper guidance so that all the students can understand easily.

Coal and Petroleum Solution :

Multiple Choice Questions :

Question no – (1)

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

Answer :

Correct option – (d)

Plastic is not a natural resource.

Question no – (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?

Answer :

Correct option – (c)

Sun-light is another inexhaustible natural resource.

Question no – (3)

Which of the following is a pair of exhaustible natural resources.

Answer :

Correct option – (d)

Wild life and minerals is the pair of exhaustible natural resources.

Question no – (4)

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

Answer :

Correct option – (d)

CNG is not obtained from coal.

Question no – (5)

Exhaustible natural resources are

Answer :

Correct option – (c)

Exhaustible natural resources are limited in quantity.

Question no – (6)

Fossil fuels are obtained from

Answer :

Correct option – (d)

Fossil fuels are obtained from dead remains of living organisms.

Question no – (7)

Coal is formed from the remains of

Answer :

Correct option – (a)

Coal is formed from the remains of vegetation only.

Question no – (8)

Which substance is formed by the carbonisation of dead vegetation?

Answer :

Correct option – (a)

Coal is formed by the carbonisation of dead vegetation.

Question no – (9)

Naphthalene balls are obtained from coal tar and are used as

Answer :

Correct option – (c)

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

Question no – (10)

Which of the following is not a constituent of petroleum?

Answer :

Correct option – (d)

Coke is not a constituent of petroleum.

Question no – (11)

Petroleum was formed from organisms

Answer :

Correct option – (c)

Petroleum was formed from organisms living in the sea.

Question no – (12)

Choose the correct statement from the following

Answer :

Correct option – (c)

Natural gas is stored under high pressure as compressed natural gas – This one is the correct statement.

Very Short Answer Questions :

Question no – (13)

Answer :

The petroleum can be easily separated from water by the process of decantation. Since petroleum is lighter than water we can separate it out by carefully pouring the upper layer into another beaker.

Question no – (14)

Answer :

CNG stands for Compressed Natural Gas. It is considered to be a better fuel than petrol because the use of it does not produce as much smoke as the use of petroleum.

Question no – (15)

Answer :

Kerosene is used as fuel for stoves, lamps and jet air crafts.

Question no – (16)

Answer :

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

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

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

(d) Petroleum, Coal and natural gas are fossil fuels.

(e) Forests and coal are Exhaustible natural resources.

Question no – (17)

Answer :

(a) Loca is obtained from mines.

= Coal

(b) Umpetlore is a fossil fuel.

= Petroleum

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

= Refinery

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

= Kerosene

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

= Sunlight

Question no – (18)

Answer :

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

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

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

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

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

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

Question no – (19)

Answer :

(a) Oxygen in air is an exhaustible natural resource

This statement is False.

Reason : Oxygen in air is an inexhaustible natural resource.

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

This statement is False

Reason : Resources which are present in unlimited quantity in nature are called inexhaustible natural resources.

(c) Wildlife is an exhaustible natural resource

This statement is True.

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

This statement is True.

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

This statement is True.

Short Answer Questions :

Question no – (20)

Answer :

Sunlight and air are referred to as inexhaustible natural resources because they will be available to us all the time, they wont be finished no matter how much we use them.

Question no – (21)

Answer :

• Exhaustible : Coal, Natural gas, Minerals, Forest, Petroleum.

• Inexhaustible : Air, Sunlight, Oxygen.

Question no – (22)

Answer :

Two important uses of coke are

• It is used in the manufacture of steels.

• It is used in the extraction of many metals.

Question no – (23)

Answer :

Characteristics of coal :

• Coal is a type of fossil fuel that is very hard in nature and black in colour.

Uses of coal :

• Coals are generally used to cook foods. In previous day it was used to power steam engine that were used in railways.

• Nowadays it is mostly used in thermal power plants to produce electricity for our homes.

Question no – (24)

Answer :

In the following figure we could clearly see that oil is above the water layer. It’s simply because of the fact that oil is lighter than water so it’s float on water.

Question no – (25)

Answer :

About 300 million years ago the earth had dense forest in low lying wetland areas. Due to natural processes, like floods, these forests got burried 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 into coal.

Question no – (26)

Answer :

(a) Used for road surfacing → (iii) Bitumen.

(b) Natural Gas → (iv) CNG.

(c) Petroleum → (i) Black Gold.

(d) Paraffin Wax → (ii) Vaseline and Candles.

Long Answer Questions :

Question no – (27)

Answer :

The products obtained and their uses when coal is processed in industry are

• Coal Tar : Coals tars are used in the manufacture of various day to day things such as naphthalene balls, synthetic dyes, drugs ,explosives, perfume, plastic paints, roofing materials and photographic materials.

• Coke : It is used in the production of steel and to extract many other metals.

• Coal gas : It is generally used as a fuel by the companies which are situated near the coal processing companies.

Question no – (28)

Answer :

Fossil fuels will last only a few thousand years. All of the fossil fuels like coal, petroleum and natural that we use today are in limited supply so if we continue to use these fuels at the rate which is more than the rate at which nature is repleneshing it, then it is for sure that one day in the near future we are going to be out of supply.

Question no – (29)

Answer :

We read in newspapers that burning of fuels is a major cause of global warming. The burning of fuels such coal and petroleum releases different types of green house gases particularly carbon dioxide into the atmosphere. These gases have this property of traping the sunlight which falls on the earth surface. This in turn increases the average temperature of the earth and cause global warming the effect of which can be devastating on the living beings and mother nature herself.

Question no – (30)

Answer :

The tips we must follow while driving to save petrol, diesel and natural gases are :

• To check if the tyres pressure are sufficient or not.

• To drive with a moderate and constant speed as far as possible.

• To regularly check the heath of our car.

• To switch off the engines at places like red lights and places were we stop for a long time.

Question no – (31)

Answer :

If all exhaustible natural resources are exhausted by human activities then the survival of living beings would be impossible. There are different exhaustible natural resources like forest, wildlife, minerals, coal, petroleum and natural gas which are extremely important to us. Forest provide us with food, oxygen and maintain balance in the nature by bringing the temperature down. Coals are massively important for the production of electrical energy which nowadays is required in almost every activity performed by a human. Wildlife are heavily responsible for maintaining a healthy balance in nature and us and fossil fuels are very important for running vehicles or industries. So without exhaustible resources we would unable to survive.

Question no – (32)

Answer :

Petrol is a exhaustible natural gas because it’s supply in nature is very limited, it could get completely depleted from nature if we use it excessively whereas sunlight is an inexhaustible natural resource because it a availability in nature does not depends on how much we use it. It’s supply in nature can not be altered even if we use it to the maximum potential.

Question no – (33)

Answer :

Some important uses of the various constituents of petroleum are :

• LPG – used as fuel for home and industry.

• Petrol – used as a fuel for automobiles and aviation.

• Kerosene – used for cooking , oil lamps and in jet aeroplane.

• Diesel – used as a fuel for heavy motor vehicles and electric generators.

• Lubricating – used as a lubricant.

• Paraffin Wax – used to manufacture ointment, candles, Vaseline etc.

• Bitumen – used as a paint and for road surfacing.

Question no – (34)

Answer :

Even if the coal reserves are said to last for a another thousand years it is still a matter of concern for us. The production of coal itself takes at least million years to form. So if we use up the coal at a faster rate than the production rate then we will have consumed coal of a thousand years so we will be out of coal till mother nature replenishes it for us.

Question no – (35)

Answer :

We should adopt the following ways to save fossil fuels :

• We should travel to places by means of public transport.

• Renewable sources of energy should be used more often for example – solar energy.

• We should not waste any fossil fuels.

• We should use cycle or walk to smaller distances.

• We should maintain all the machinery that needs fuels to run.

• We should switch off the engines at places were we stop for a long duration such as traffic lights.

Other Chapter Solutions :

👉 Crop Production and Management

👉 Microorganisms : Friend and Foe