DAV Class 8 Science Chapter 6 Question Answer – Sources of Energy

The DAV Class 8 Science Book Solutions Pdf and DAV Class 8 Science Chapter 6 Question Answer – Sources of Energy are essential study tools for DAV public school students in Class 8.

DAV Class 8 Science Ch 6 Question Answer – Sources of Energy

DAV Class 8 Science Ch 6 Solutions – Sources of Energy

Something To Know

A. Fill in the blanks:

Question 1.
________ and ________ are non-renewable sources of energy.
Answer:
coal, petroleum

Question 2.
________ is a major renewable, natural resource.
Answer:
water

Question 3.
The process in which coal is strongly heated in the absence of air is known as ________ .
Answer:
destructive distillation

Question 4.
In oil wells ________ is always found above the layer of petroleum.
Answer:
natural gas

Question 5.
________ is a black viscous liquid, obtained by destructive distillation of coal.
Answer:
coal tar

B. State True or False for the following statements:

1. Fossil fuels are renewable natural resources.
Answer:
False

2. Anthracite has higher carbon content than lignite.
Answer:
True

3. Coke can be used to make fuel gases.
Answer:
True

4. Natural gas is found below the petroleum layers.
Answer:
False

5. Burning of fossil fuels is a major source of pollution.
Answer:
True

C. Tick (✓) the correct option:

Question 1.
The highest grade of coal is known as-
(a) Lignite
(b) Bitumen
(c) Anthracite
(d) Peat
Answer:
(c) Anthracite

Question 2.
Coke and coal tar are obtained from-
(a) Petroleum
(b) Coal
(c) Natural gas
(d) Diesel
Answer:
(b) Coal

Question 3.
Different types of coal generally have the-
(a) Same content of volatile material and same percentage of carbon
(b) Same content of volatile material but different percentage of carbon
(c) Different content of volatile material but same percentage of carbon
(d) Different content of volatile material as well as different percentage of carbon
Answer:
(d) Different content of volatile material as well as different percentage of carbon

Question 4.
A product, that is not obtained through the refining of petroleum, is
(a) Diesel
(b) Kerosene
(c) Coal gas
(d) Petrol
Answer:
(c) Coal gas

Question 5.
Which of the following is a renewable source of energy?
(a) Tidal energy
(b) Coal
(c) Diesel
(d) Petrol
Answer:
Tidal energy

D. Answer the following questions in brief:

Question 1.
Define the term ‘fuel’.
Answer:
A substance which produces heat on burning in air is called fuel.

Question 2.
Name any two renewable natural sources of energy.
Answer:
Wind energy, Solar energy

Question 3.
Define the term ‘carbonisation’.
Answer:
The process of conversion of dead plant materials into coal is called carbonization.

Question 4.
Name the three main products obtained from destructive distillation of coal.
Answer:
Petrol, diesel and kerosene

Question 5.
State two uses of each of the following:
(a) Asphalt
Answer:
Asphalt is used for making road and painting the underside of electric pole.

(b) Paraffin wax
Answer:
For making ointments and candles

Question 6.
Write the full forms of CNG, LPG and PNG.
Answer:
CNG: Compressed Natural Gas
LPG: Liquefied Petroleum Gas
PNG: Piped Natural Gas

E. Answer the following questions:

Question 1.
Describe, in brief, the process of ‘coal formation.
Answer:
Millions of years ago, plants got buried under the earth’s crust. In due course of time, those dead remains of plants got converted into coal due intense pressure and temperature inside the earth. The process of conversion of remains of plants into coal is called carbonization.

Question 2.
Differentiate between lignite and bituminous coal.
Answer:

Lignite	Bituminous coal
It contains about 38% carbon.	It contains about 65% carbon.
It is mainly used for power generation.	It is used for power generation and for making coke.

Question 3.
How do petroleum and natural gas occur in nature?
Answer:
Petroleum occurs in rock formations as crude oil. Crude oil is a dark, viscous and foul smelling liquid. Natural gas is found in oil wells above the crude oil.

Question 4.
State the main advantages of using natural gas.
Answer:
Advantages of using natural gas:

• It is a clean fuel.
• It is easy to transport natural gas through pipelines.
• Natural gas is economical than petrol and diesel.

Question 5.
Keeping in mind their availability in nature, explain the need of using coal and petroleum judiciously.
Answer:
Coal and petroleum are non-renewable resources. Their stock is going to be finished in near future. Hence, it is necessary to use them judiciously.

Value Based Question

The chemistry teacher, explained to her students that when petroleum, a naturally occurring fossil fuel, is separated into its different components, each of these components is useful in one way or the other. She then told her students that our daily life too can be thought of as ‘made up’ of a number of activities, actions and tasks. She suggested that ‘all of us’ should try to ensure and aim that all these ‘components’ of our daily life, are useful/helpful to the society at large.

Question 1.
State the values that you think are contained in the teacher’s talk and suggestions.
Answer:
Positive contribution of our activities to the society.

Question 2.
Name any three components, obtained from petroleum, and state any one use of each of them.
Answer:
Three components obtained from petroleum and their uses are as follows:

• Petrol: As fuel in cars.
• Diesel: As fuel in buses.
• Asphalt: For making road surface.

Question 3.
Have a ‘group discussion’ in which different students suggest “ways and means’ of making their different daily life actions and activities, useful to the society at large.
Answer:
Do it yourself

Something To Do

Question 1.
Make a report on ‘electricity consumption’ in your house. Suggest some ways that can help to reduce the consumption.
Answer:
Make the report yourself. Some ways to reduce electricity consumption are as follows:

• Switch off lights and fans when not in use.
• Do not use airconditioner until it is absolutely necessary.
• Use LED or CFL instead of incandescent bulbs.
• Use appliances with good energy rating.

Question 2.
Unlike thermal power plants, which burn fossil fuels and emit large amounts of carbon dioxide (a greenhouse gas) into the atmosphere, nuclear power plants use uranium (a metal) to produce huge amounts of energy from very small amount o fuel. However, they release harmful radiations that can pose a high risk to the population.
Do you think nuclear energy can be an answer to the problems caused by the use of fossil fuels? Try to prepare a report, listing points that suggest that nuclear power could be/could not be a better way of generating electricity as compared to fossil fuels.
Answer:
Replacing fossil fuels with nuclear energy can indeed help in reducing air pollution. But long term harms by potential leak of radiation is too costly for human life. Hence, nuclear energy cannot be a better way of generating electricity as compared to fossil fuels. We need to adapt other approaches for this; such as solar energy and hydel energy.

Question 3.
Try to find out information about the places/activities for which solar energy or wind energy is being put to use in place of conventional fossil fuel based energy sources.
Answer:
India has progressed significantly in the fields of solar energy and wind energy. Many solar power plants have come up in Rajasthan. Similarly, Tamil Nadu is the leading state in terms of wind energy.

DAV Class 8 Science Chapter 6 Solutions – Sources of Energy Important Questions and Answers

I. Fill in the blanks:

1. Battery is a ________ source of energy.
Answer:
Man-made

2. Firewood is used as ________ fuel in rural areas.
Answer:
Kitchen

3. LPG is used as ________ fuel.
Answer:
Domestic

4. CNG is used as fuel for ________ .
Answer:
Automobiles

5. Coal is a type ________ of rock.
Answer:
Sedimentary

II. Tick (✓) the correct answer:

Question 1.
Which of these is a man-made source of energy?
(a) Petrol
(b) Diesel
(c) Battery
(d) Wind energy
Answer:
(c) Battery

Question 2.
Which of these is non-renewable source of energy?
(a) Coal
(b) Hydel energy
(c) Solar energy
(d) Wind energy
Answer:
(a) Coal

Question 3.
Which of these produces lot of polluting gases on burning?
(a) LPG
(b) CNG
(c) Diesel
(d) All of these
Answer:
(c) Diesel

Question 4.
Coal mines are located at which of these places?
(a) Krishna Godavari Basin
(b) Bombay High
(c) Digboi
(d) Jharia
Answer:
(d) Jharia

Question 5.
A petroleum refinery is located at which of these places?
(a) Mathura
(b) Bokaro
(c) Bhilai
(d) Durgapur
Answer:
(a) Mathura

III. Answer the following questions:

Question 1.
What do you understand by non-renewable sources of energy?
Answer:
A source of energy which gets used up and cannot be recreated in a short period of time is called non-renewable source of energy. These are also called exhaustible source of energy, e.g. fossil fuels.

Question 2.
What is a fossil fuel?
Answer:
The fuels which were formed from dead remains of plants and animals are called fossil fuels.

Question 3.
What are the different types of coal?
Answer:
Peat, lignite, bituminous and anthracite are different types of coal.

Question 4.
What are the uses of coal gas?
Answer:
Uses of coal gas:

• It is used as domestic fuel.
• It is used as industrial fuel in those industries which are located near coal processing units.

Question 5.
Write a brief note on processing of coal.
Answer:
Coal is processed through destructive distillation. This is done by strong heating of coal in the absence of air. This helps in retaining useful contents of coal and removing unwanted components so that coal can produce optimum amount of energy. Coke, coal tar, and coal gas are also obtained during destructive distillation of coal.

IV. Projects:

Question 1.
Using a basket and aluminium foil, make a solar cooker. Demonstrate its working in your school.
Answer:
Do it yourself

Question 2.
What changes would you bring in your daily life to reduce environmental pollution? Make a project report.
Answer:
Do it yourself