Lesson: Coal and Petroleum
Topic 1: Formation and Application of Coal

Question: 1

What are natural resources?

Solution:

All materials that are found in the environment in a natural form undisturbed by human activity are called natural resources. Examples of natural resources are sunlight, water, air, soil, forest, minerals and so on.

Question: 2

What are the inexhaustible natural resources?

Solution:

Natural resources that are available to us in unlimited quantities and that do not get depleted even after constant use, are called inexhaustible natural resources. Examples are sunlight, water and wind.

Question: 3

What are the exhaustible natural resources?

Solution:

Natural resources that are available to us in limited quantities, once used, cannot be replaced, re-grown or regenerated within a reasonable period of time are called exhaustible natural resources. Examples are natural vegetation, minerals and natural gases.

Question: 4

Distinguish between exhaustible & inexhaustible natural resources. Give examples.

Solution:

Natural resources that are available to us in unlimited quantities and that do not get depleted even after constant use, are called inexhaustible natural resources. Examples are sunlight, water and wind.

On the other hand, natural resources that are available to us in limited quantities, once used, cannot be replaced, re-grown or regenerated within a reasonable period of time are called exhaustible natural resources. Examples are natural vegetation, minerals and natural gases.

Question: 5

Explain the term carbonisation.

Solution:

The process of conversion of dead vegetation into coal is called carbonisation.

Question: 6

Explain the characteristics and uses of coke.

Solution:

Coke is a tough, porous and greyish black solid substance that is derived from coal and is also considered as the purest form of carbon.

The uses of coke are as follows:

Domestic fuel for cooking

In the manufacturing of steel and extraction of various metals from their respective ores

In thermal power plants for generation of electricity

In steam engines for rail transportation

Question: 7

What is meant by fuel?

Solution:

Fuel is a substance that burns in air to produce heat energy.

Question: 8

How can we obtain the coal gas?

Solution:

The gaseous mixture of coal gas is obtained during the processing of coal to get coke.

Question: 9

Give three uses of coal.

Solution:

Coal is used:

(i)                     For generation of electricity

(ii)                   In iron and steel production

(iii)                 In the manufacture of cement

(iv)                 As a domestic cooking fuel

Question: 10

Name three products obtained after the processing of coal. Also mention their uses.

Solution:

Once coal is extracted from mines, it undergoes a process of heating at very high temperature, done in the absence of air.  Thereby, many by-products are produced which have many different uses.

The by-products and their uses are:

(i)                 Coal gas - It is used as a fuel in cooking food and for street lighting.

(ii)              Coke - It is used as a fuel and as a reducing agent in steel manufacturing.

(iii)            Coal tar- It is used to make plastics, paints, dyes, naphthalene balls, explosives, perfumes etc.

Question: 11

Describe how coal is formed from dead vegetation.

Solution:

Coal is a hard, black fossil fuel that was formed in the carboniferous period, over 300 million years ago, when the earth was covered with oceans, swamps, trees and plants.  Plants that died fell into the water bodies and swamps. Due to lack of oxygen under water, the dead plants did not decay completely. Instead, they turned into layers of peat, a brown material consisting of partly decomposed vegetable matter.

As the years passed, the layers of forests sank deeper and were exposed to high pressure and temperature underground. The peat then changed into lignite, a soft coal which is brown in colour.

This lignite got covered further under more layers of sand, clay and other materials.

As the lignite got buried deeper and deeper underground, it got exposed to both high pressure and high temperature.

This made the lignite harder and darker and finally it was transformed into coal.

Since coal comprises mainly of carbon, this process of conversion of dead vegetation into coal is called carbonisation.

Question: 12

What are fossil fuels?

Solution:

Fossils are the remains of the dead plants and animals like dinosaurs that got buried deep under the earth’s layer millions of years ago. Fuels such as coal, petroleum and natural gas were formed naturally from the dead remains living organisms millions of years ago, and are called fossil fuels.

Question: 13

Give two examples of exhaustible and inexhaustible natural resources.

Solution:

Exhaustible natural resource $–$ coal and petroleum

Inexhaustible natural resource $–$ air and water

Topic 2: Formation and Application of Oil & Natural Gas

Question: 1

What are the main uses of natural gas?

Solution:

The main uses of natural gas are:

·         As cooking gas in homes

·         As Compressed natural gas (CNG), a fuel for vehicles

·         As a fuel in thermal power stations to generate electricity

·         In the manufacture of chemicals and fertilisers

Question: 2

Why natural gas is called an ideal fuel?

Solution:

Natural gas is called an ideal fuel because it:

·         burns with smokeless flame

·         does not leave ash

·         produces significant amount of heat

Question: 3

What are the advantages of using CNG and LPG as fuels?

Solution:

The advantages of using compressed natural gas (CNG) and liquefied petroleum gas (LPG) as fuels are:

·         They can be burnt directly.

·         They can be easily transported; either in cylinders or through pipelines.

·         They are refined fuels and do not release smoke when burnt.

·         They give a lot of heat energy when burnt.

·         They are more efficient than other conventional fuels.

Question: 4

Describe natural gas and its uses.

Solution:

Natural gas is a fossil fuel formed when layers of decaying buried plants and animals are exposed to intense heat and pressure. Natural gas is one of the cleanest, most convenient and most economical of all fuels. It can be delivered through underground pipelines directly to each household. It is used mainly for cooking as it burns easily, with a smokeless flame and produces a significant amount of heat.

It is also stored under high pressure in cylinders as Compressed Natural Gas (CNG). CNG can be conveniently used as fuel for running vehicles.

Besides this, natural gas is also used as a fuel in thermal power stations for generating electricity and as a raw material for the manufacture of a number of chemicals and fertilisers.

Question: 5

How can we save petrol and diesel while driving?

Solution:

Following simple steps can save petrol and diesel:

·         Drive at a constant and moderate speed as far as possible.

·         Switch off the engine at traffic lights or at places where you have to wait.

·         Ensure correct tyre pressure.

·         Ensure regular maintenance of the vehicle.

Question: 6

Why should we use the fossil fuels economically?

Solution:

The consumption of fossil fuels is increasing rapidly due to growth in population and industrialisation. Since these fuels are exhaustible, they cannot be replenished easily. Therefore, we need to conserve them by using them economically and wisely.

Besides consumption, there is another reason for saving fossil fuels wisely. This is to protect our environment. Burning of fossil fuels causes air pollution and is directly linked to global warming.

Question: 7

Which petroleum product is used for surfacing of roads?

Solution:

Bitumen, is a petroleum product used for surfacing of roads.

Question: 8

What is the full form of CNG?

Solution:

CNG stands for Compressed Natural Gas.

Question: 9

What is the full form of LPG?

Solution:

LPG stands for Liquefied Petroleum Gas.

Question: 10

What is petroleum?

Solution:

Petroleum is a dark coloured, liquid fossil fuel that is found deep inside the earth, and formed naturally from decayed prehistoric plant and animal remains.

Question: 11

Why is petroleum called black gold?

Solution:

The constituents of petroleum are very useful for us, which makes it a very precious resource. Due to its great commercial importance, petroleum is also called 'black gold'.

Question: 12

What are petrochemicals?

Solution:

Chemical products obtained from petroleum and natural gas are called “petrochemicals”.

Question: 13

What is petroleum refining?

Solution:

The process of separating the various constituents of petroleum is called petroleum refining.

Question: 14

How petroleum is formed and how it is obtained?

Solution:

Animals and plants that got buried at the bottom of the sea millions of years ago got covered with layers of sand and clay, forming sediments. Due to high pressure and temperature, they slowly got converted into fossil fuels like coal, petroleum and natural gas.

Petroleum is extracted using giant drilling machines that bore deep into the earth.

Question: 15

List various constituents of petroleum with their uses.

Solution:

The constituents of petroleum with their uses are given below:

·         LPG: Used as a fuel for domestic as well as industrial purposes

·         Petrol: Used as motor fuel, aviation fuel, and as a solvent for dry cleaning

·         Kerosene: Used as fuel for stoves, lamps and to power jet engines or aircrafts

·         Diesel: Used as fuel for heavy motor vehicles and electric generators

·         Lubricating Oil: Used as a lubricating agent

·         Paraffin Wax: Used in ointments and candles

·         Bitumen: Used in paints and for road surfacing

Question: 16

What are the harmful effects of burning fossil fuels?

Solution:

Burning fossil fuels:

·         Causes air pollution

·         Causes global warming because they produce greenhouse gases like carbon dioxide on burning