Textbook Solutions: Natural Resources – Air, Water and Land | General Science Class 6 (Maharashtra Board) PDF Download

 Page 1


Chapter 1: Natural Resources –Air, Water & Land 
 
 
EXERCISE [PAGE 8] 
Exercise | Q 1.1 | Page 8 
Fill in the blank 
The layer of ozone gas absorbs ………… rays that come from the sun to the earth. 
 
SOLUTION 
The layer of ozone gas absorbs UV rays that come from the sun to the earth. 
Exercise | Q 1.2 | Page 8 
Fill in the blank 
Of the total water available on the earth, fresh water forms ...... percent. 
 
SOLUTION 
Of the total water available on the earth, fresh water forms 0.3 percent. 
Exercise | Q 1.3 | Page 8 
Fill in the blank 
Both ______ and _______ constituents are present in the soil. 
 
SOLUTION 
Both biotic and abiotic constituents are present in the soil. 
Exercise | Q 2.1 | Page 8 
Why is it said that – The ozone layer is a protective shell of the earth? 
 
SOLUTION 
The ozone layer acts as a protective layer for life on the earth because it absorbs 
harmful ultraviolet radiation of the sun. These radiations, if reach the Earth’s surface, 
can cause skin cancer. 
Exercise | Q 2.2 | Page 8 
Why is it said that – Water is life? 
 
SOLUTION 
Water is one of the most precious resources which we have on earth. All the 
biochemical processes which occur in plants and animals, our surroundings, etc. require 
water to function. It is required for the existence of life on earth as it is an essential 
component of all the biological processes. We cannot imagine our lives without the 
presence of water.  
 
Page 2


Chapter 1: Natural Resources –Air, Water & Land 
 
 
EXERCISE [PAGE 8] 
Exercise | Q 1.1 | Page 8 
Fill in the blank 
The layer of ozone gas absorbs ………… rays that come from the sun to the earth. 
 
SOLUTION 
The layer of ozone gas absorbs UV rays that come from the sun to the earth. 
Exercise | Q 1.2 | Page 8 
Fill in the blank 
Of the total water available on the earth, fresh water forms ...... percent. 
 
SOLUTION 
Of the total water available on the earth, fresh water forms 0.3 percent. 
Exercise | Q 1.3 | Page 8 
Fill in the blank 
Both ______ and _______ constituents are present in the soil. 
 
SOLUTION 
Both biotic and abiotic constituents are present in the soil. 
Exercise | Q 2.1 | Page 8 
Why is it said that – The ozone layer is a protective shell of the earth? 
 
SOLUTION 
The ozone layer acts as a protective layer for life on the earth because it absorbs 
harmful ultraviolet radiation of the sun. These radiations, if reach the Earth’s surface, 
can cause skin cancer. 
Exercise | Q 2.2 | Page 8 
Why is it said that – Water is life? 
 
SOLUTION 
Water is one of the most precious resources which we have on earth. All the 
biochemical processes which occur in plants and animals, our surroundings, etc. require 
water to function. It is required for the existence of life on earth as it is an essential 
component of all the biological processes. We cannot imagine our lives without the 
presence of water.  
 
Exercise | Q 2.3 | Page 8 
Why is it said that – Seawater is useful even though it is not potable? 
SOLUTION 
Although seawater is not potable, it has various other kinds of uses which prove its 
importance: 
• Water from oceans can be used for making hydroelectricity, a form of renewable 
source of energy. 
• It can be used as a cheap transport method. 
• They can be used for activities like scuba diving, water sports, etc. which is a 
means of boosting the tourism and economic growth of a country. 
• Nuclear power plants require coolants like water to bring down the temperature 
of the reactors. For this purpose, several gallons of water are required and this 
demand is fulfilled by the water from oceans. 
• They support a variety of flora and fauna which have both ecological and 
economical value. 
 
Exercise | Q 3.1 | Page 8 
What will happen if – Microbes in the soil get destroyed? 
SOLUTION 
Soil contains various kinds of microbes like bacteria, fungi, algae, protozoa, etc. All of 
these microorganisms play important roles like: 
• Certain bacteria and blue-green algae have the ability to fix atmospheric 
nitrogen. This, in turn, enriches the fertility of the soil. Such microorganisms are 
known as biological nitrogen-fixers. Example - Rhizobium is a symbiotic 
bacterium that lives in the root nodules of leguminous plants. Rhizobium fixes 
atmospheric nitrogen into nitrogenous compounds. 
• The bacteria and fungi present in soil decompose dead organic wastes of plants 
and animals and convert them into manure. The manure contributes to the 
humus content of the soil, thereby helping in increasing its fertility. 
• Not only these, microorganisms that are found in soil are also a part of many 
biogeochemical cycles that would not take place in their absence. 
Page 3


Chapter 1: Natural Resources –Air, Water & Land 
 
 
EXERCISE [PAGE 8] 
Exercise | Q 1.1 | Page 8 
Fill in the blank 
The layer of ozone gas absorbs ………… rays that come from the sun to the earth. 
 
SOLUTION 
The layer of ozone gas absorbs UV rays that come from the sun to the earth. 
Exercise | Q 1.2 | Page 8 
Fill in the blank 
Of the total water available on the earth, fresh water forms ...... percent. 
 
SOLUTION 
Of the total water available on the earth, fresh water forms 0.3 percent. 
Exercise | Q 1.3 | Page 8 
Fill in the blank 
Both ______ and _______ constituents are present in the soil. 
 
SOLUTION 
Both biotic and abiotic constituents are present in the soil. 
Exercise | Q 2.1 | Page 8 
Why is it said that – The ozone layer is a protective shell of the earth? 
 
SOLUTION 
The ozone layer acts as a protective layer for life on the earth because it absorbs 
harmful ultraviolet radiation of the sun. These radiations, if reach the Earth’s surface, 
can cause skin cancer. 
Exercise | Q 2.2 | Page 8 
Why is it said that – Water is life? 
 
SOLUTION 
Water is one of the most precious resources which we have on earth. All the 
biochemical processes which occur in plants and animals, our surroundings, etc. require 
water to function. It is required for the existence of life on earth as it is an essential 
component of all the biological processes. We cannot imagine our lives without the 
presence of water.  
 
Exercise | Q 2.3 | Page 8 
Why is it said that – Seawater is useful even though it is not potable? 
SOLUTION 
Although seawater is not potable, it has various other kinds of uses which prove its 
importance: 
• Water from oceans can be used for making hydroelectricity, a form of renewable 
source of energy. 
• It can be used as a cheap transport method. 
• They can be used for activities like scuba diving, water sports, etc. which is a 
means of boosting the tourism and economic growth of a country. 
• Nuclear power plants require coolants like water to bring down the temperature 
of the reactors. For this purpose, several gallons of water are required and this 
demand is fulfilled by the water from oceans. 
• They support a variety of flora and fauna which have both ecological and 
economical value. 
 
Exercise | Q 3.1 | Page 8 
What will happen if – Microbes in the soil get destroyed? 
SOLUTION 
Soil contains various kinds of microbes like bacteria, fungi, algae, protozoa, etc. All of 
these microorganisms play important roles like: 
• Certain bacteria and blue-green algae have the ability to fix atmospheric 
nitrogen. This, in turn, enriches the fertility of the soil. Such microorganisms are 
known as biological nitrogen-fixers. Example - Rhizobium is a symbiotic 
bacterium that lives in the root nodules of leguminous plants. Rhizobium fixes 
atmospheric nitrogen into nitrogenous compounds. 
• The bacteria and fungi present in soil decompose dead organic wastes of plants 
and animals and convert them into manure. The manure contributes to the 
humus content of the soil, thereby helping in increasing its fertility. 
• Not only these, microorganisms that are found in soil are also a part of many 
biogeochemical cycles that would not take place in their absence. 
The above points explain the fact that how important microbes are and if they are 
destroyed its effect can be irreversible. 
Exercise | Q 3.2 | Page 8 
What will happen if – The number of vehicles and factories in your surroundings 
increases? 
 
SOLUTION 
Vehicles and factories are the major sources of air pollution. If the number of vehicles 
and factories increase in our surroundings, it is obvious that it would result in increased 
levels of air pollution. Not only air pollution but they also result in noise pollution. In 
case, the no. of industries increase in our surrounding it means, more trees would have 
to be cut down to make way for them and thus resulting in damage to the environment. 
Exercise | Q 3.3 | Page 8 
What will happen if – The total supply of potable water is finished? 
 
SOLUTION 
If the total supply of potable water is finished then the life on earth will end. Water is 
required for the existence of living beings and in its absence, it owuld hamper their 
development process and their survival. 
Exercise | Q 4 | Page 8 
Match the following 
  
Group ‘A’ Group ‘B’ 
(1) Carbon dioxide (a) Generation of soil 
(2) Oxygen (b) Rain 
(3) Water vapour (c) Plants and food 
production 
(4) Microbes (d) Combustion 
 
SOLUTION 
 
Group ‘A’ Group ‘B’ 
(1) Carbon dioxide (c) Plants and food production 
(2) Oxygen (d) Combustion 
(3) Water vapour (b) Rain 
(4) Microbes (a) Generation of soil 
Page 4


Chapter 1: Natural Resources –Air, Water & Land 
 
 
EXERCISE [PAGE 8] 
Exercise | Q 1.1 | Page 8 
Fill in the blank 
The layer of ozone gas absorbs ………… rays that come from the sun to the earth. 
 
SOLUTION 
The layer of ozone gas absorbs UV rays that come from the sun to the earth. 
Exercise | Q 1.2 | Page 8 
Fill in the blank 
Of the total water available on the earth, fresh water forms ...... percent. 
 
SOLUTION 
Of the total water available on the earth, fresh water forms 0.3 percent. 
Exercise | Q 1.3 | Page 8 
Fill in the blank 
Both ______ and _______ constituents are present in the soil. 
 
SOLUTION 
Both biotic and abiotic constituents are present in the soil. 
Exercise | Q 2.1 | Page 8 
Why is it said that – The ozone layer is a protective shell of the earth? 
 
SOLUTION 
The ozone layer acts as a protective layer for life on the earth because it absorbs 
harmful ultraviolet radiation of the sun. These radiations, if reach the Earth’s surface, 
can cause skin cancer. 
Exercise | Q 2.2 | Page 8 
Why is it said that – Water is life? 
 
SOLUTION 
Water is one of the most precious resources which we have on earth. All the 
biochemical processes which occur in plants and animals, our surroundings, etc. require 
water to function. It is required for the existence of life on earth as it is an essential 
component of all the biological processes. We cannot imagine our lives without the 
presence of water.  
 
Exercise | Q 2.3 | Page 8 
Why is it said that – Seawater is useful even though it is not potable? 
SOLUTION 
Although seawater is not potable, it has various other kinds of uses which prove its 
importance: 
• Water from oceans can be used for making hydroelectricity, a form of renewable 
source of energy. 
• It can be used as a cheap transport method. 
• They can be used for activities like scuba diving, water sports, etc. which is a 
means of boosting the tourism and economic growth of a country. 
• Nuclear power plants require coolants like water to bring down the temperature 
of the reactors. For this purpose, several gallons of water are required and this 
demand is fulfilled by the water from oceans. 
• They support a variety of flora and fauna which have both ecological and 
economical value. 
 
Exercise | Q 3.1 | Page 8 
What will happen if – Microbes in the soil get destroyed? 
SOLUTION 
Soil contains various kinds of microbes like bacteria, fungi, algae, protozoa, etc. All of 
these microorganisms play important roles like: 
• Certain bacteria and blue-green algae have the ability to fix atmospheric 
nitrogen. This, in turn, enriches the fertility of the soil. Such microorganisms are 
known as biological nitrogen-fixers. Example - Rhizobium is a symbiotic 
bacterium that lives in the root nodules of leguminous plants. Rhizobium fixes 
atmospheric nitrogen into nitrogenous compounds. 
• The bacteria and fungi present in soil decompose dead organic wastes of plants 
and animals and convert them into manure. The manure contributes to the 
humus content of the soil, thereby helping in increasing its fertility. 
• Not only these, microorganisms that are found in soil are also a part of many 
biogeochemical cycles that would not take place in their absence. 
The above points explain the fact that how important microbes are and if they are 
destroyed its effect can be irreversible. 
Exercise | Q 3.2 | Page 8 
What will happen if – The number of vehicles and factories in your surroundings 
increases? 
 
SOLUTION 
Vehicles and factories are the major sources of air pollution. If the number of vehicles 
and factories increase in our surroundings, it is obvious that it would result in increased 
levels of air pollution. Not only air pollution but they also result in noise pollution. In 
case, the no. of industries increase in our surrounding it means, more trees would have 
to be cut down to make way for them and thus resulting in damage to the environment. 
Exercise | Q 3.3 | Page 8 
What will happen if – The total supply of potable water is finished? 
 
SOLUTION 
If the total supply of potable water is finished then the life on earth will end. Water is 
required for the existence of living beings and in its absence, it owuld hamper their 
development process and their survival. 
Exercise | Q 4 | Page 8 
Match the following 
  
Group ‘A’ Group ‘B’ 
(1) Carbon dioxide (a) Generation of soil 
(2) Oxygen (b) Rain 
(3) Water vapour (c) Plants and food 
production 
(4) Microbes (d) Combustion 
 
SOLUTION 
 
Group ‘A’ Group ‘B’ 
(1) Carbon dioxide (c) Plants and food production 
(2) Oxygen (d) Combustion 
(3) Water vapour (b) Rain 
(4) Microbes (a) Generation of soil 
Exercise | Q 5.1 | Page 8 
Name the following. 
Constituents of the biosphere 
 
SOLUTION 
Constituents of the biosphere- hydrosphere and atmosphere 
Exercise | Q 5.2 | Page 8 
Name the following. 
Biotic constituents of soil 
 
SOLUTION 
Biotic constituents of soil- microorganisms and insects 
Exercise | Q 5.3 | Page 8 
Name the following. 
Fossil fuel 
 
SOLUTION 
Fossil fuel- coal and petroleum 
Exercise | Q 5.4 | Page 8 
Name the following. 
Inert gases in the air 
 
SOLUTION 
Inert gases in the air: 
1. Helium 
2. Neon 
3. Argon 
4. Radon 
5. Xenon 
6. Krypton 
 
Exercise | Q 5.5 | Page 8 
Name the following. 
Gases that are harmful to the ozone layer 
 
SOLUTION 
Gases that are harmful to the ozone layer- carbon tetrachloride 
Exercise | Q 6.1 | Page 8 
True or false? 
Page 5


Chapter 1: Natural Resources –Air, Water & Land 
 
 
EXERCISE [PAGE 8] 
Exercise | Q 1.1 | Page 8 
Fill in the blank 
The layer of ozone gas absorbs ………… rays that come from the sun to the earth. 
 
SOLUTION 
The layer of ozone gas absorbs UV rays that come from the sun to the earth. 
Exercise | Q 1.2 | Page 8 
Fill in the blank 
Of the total water available on the earth, fresh water forms ...... percent. 
 
SOLUTION 
Of the total water available on the earth, fresh water forms 0.3 percent. 
Exercise | Q 1.3 | Page 8 
Fill in the blank 
Both ______ and _______ constituents are present in the soil. 
 
SOLUTION 
Both biotic and abiotic constituents are present in the soil. 
Exercise | Q 2.1 | Page 8 
Why is it said that – The ozone layer is a protective shell of the earth? 
 
SOLUTION 
The ozone layer acts as a protective layer for life on the earth because it absorbs 
harmful ultraviolet radiation of the sun. These radiations, if reach the Earth’s surface, 
can cause skin cancer. 
Exercise | Q 2.2 | Page 8 
Why is it said that – Water is life? 
 
SOLUTION 
Water is one of the most precious resources which we have on earth. All the 
biochemical processes which occur in plants and animals, our surroundings, etc. require 
water to function. It is required for the existence of life on earth as it is an essential 
component of all the biological processes. We cannot imagine our lives without the 
presence of water.  
 
Exercise | Q 2.3 | Page 8 
Why is it said that – Seawater is useful even though it is not potable? 
SOLUTION 
Although seawater is not potable, it has various other kinds of uses which prove its 
importance: 
• Water from oceans can be used for making hydroelectricity, a form of renewable 
source of energy. 
• It can be used as a cheap transport method. 
• They can be used for activities like scuba diving, water sports, etc. which is a 
means of boosting the tourism and economic growth of a country. 
• Nuclear power plants require coolants like water to bring down the temperature 
of the reactors. For this purpose, several gallons of water are required and this 
demand is fulfilled by the water from oceans. 
• They support a variety of flora and fauna which have both ecological and 
economical value. 
 
Exercise | Q 3.1 | Page 8 
What will happen if – Microbes in the soil get destroyed? 
SOLUTION 
Soil contains various kinds of microbes like bacteria, fungi, algae, protozoa, etc. All of 
these microorganisms play important roles like: 
• Certain bacteria and blue-green algae have the ability to fix atmospheric 
nitrogen. This, in turn, enriches the fertility of the soil. Such microorganisms are 
known as biological nitrogen-fixers. Example - Rhizobium is a symbiotic 
bacterium that lives in the root nodules of leguminous plants. Rhizobium fixes 
atmospheric nitrogen into nitrogenous compounds. 
• The bacteria and fungi present in soil decompose dead organic wastes of plants 
and animals and convert them into manure. The manure contributes to the 
humus content of the soil, thereby helping in increasing its fertility. 
• Not only these, microorganisms that are found in soil are also a part of many 
biogeochemical cycles that would not take place in their absence. 
The above points explain the fact that how important microbes are and if they are 
destroyed its effect can be irreversible. 
Exercise | Q 3.2 | Page 8 
What will happen if – The number of vehicles and factories in your surroundings 
increases? 
 
SOLUTION 
Vehicles and factories are the major sources of air pollution. If the number of vehicles 
and factories increase in our surroundings, it is obvious that it would result in increased 
levels of air pollution. Not only air pollution but they also result in noise pollution. In 
case, the no. of industries increase in our surrounding it means, more trees would have 
to be cut down to make way for them and thus resulting in damage to the environment. 
Exercise | Q 3.3 | Page 8 
What will happen if – The total supply of potable water is finished? 
 
SOLUTION 
If the total supply of potable water is finished then the life on earth will end. Water is 
required for the existence of living beings and in its absence, it owuld hamper their 
development process and their survival. 
Exercise | Q 4 | Page 8 
Match the following 
  
Group ‘A’ Group ‘B’ 
(1) Carbon dioxide (a) Generation of soil 
(2) Oxygen (b) Rain 
(3) Water vapour (c) Plants and food 
production 
(4) Microbes (d) Combustion 
 
SOLUTION 
 
Group ‘A’ Group ‘B’ 
(1) Carbon dioxide (c) Plants and food production 
(2) Oxygen (d) Combustion 
(3) Water vapour (b) Rain 
(4) Microbes (a) Generation of soil 
Exercise | Q 5.1 | Page 8 
Name the following. 
Constituents of the biosphere 
 
SOLUTION 
Constituents of the biosphere- hydrosphere and atmosphere 
Exercise | Q 5.2 | Page 8 
Name the following. 
Biotic constituents of soil 
 
SOLUTION 
Biotic constituents of soil- microorganisms and insects 
Exercise | Q 5.3 | Page 8 
Name the following. 
Fossil fuel 
 
SOLUTION 
Fossil fuel- coal and petroleum 
Exercise | Q 5.4 | Page 8 
Name the following. 
Inert gases in the air 
 
SOLUTION 
Inert gases in the air: 
1. Helium 
2. Neon 
3. Argon 
4. Radon 
5. Xenon 
6. Krypton 
 
Exercise | Q 5.5 | Page 8 
Name the following. 
Gases that are harmful to the ozone layer 
 
SOLUTION 
Gases that are harmful to the ozone layer- carbon tetrachloride 
Exercise | Q 6.1 | Page 8 
True or false? 
Land and soil are the same things. 
1. True 
2. False 
 
SOLUTION 
Land and soil are the same thing.- False 
Exercise | Q 6.2 | Page 8 
True or false? 
The water in a lake is called ground water. 
1. True 
2. False 
 
SOLUTION 
The water in a lake is called ground water.- False 
Exercise | Q 6.3 | Page 8 
True or false? 
It takes about 1000 years to form a 25 cm thick layer of soil. 
1. True 
2. False 
 
SOLUTION 
It takes about 1000 years to form a 25 cm thick layer of soil.-False 
Exercise | Q 6.4 | Page 8 
True or false? 
Radon is used in decorative lights. 
1. True  
2. False 
 
SOLUTION 
Radon is used in decorative lights.- False 
Exercise | Q 7.1 | Page 8 
Answer in your own words. 
Explain with the help of a diagram of how soil is formed. 
 
SOLUTION 
Soil is formed by the process of weathering during which rocks break down to form soil 
particles. This breaking down of rock occurs over a period of millions of years. 
Weathering can be physical, chemical, and biological. The bedrock breaks down into 
pieces due to the effects of heat, cold, water, wind, and rain. Microbes, insects, and 
rodents also help in this process. The roots of trees also help in the process of 
weathering.