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Chapter 1: Natural Resources: Air, Water

and Land

1

Let’s Revise

1. Natural Resources: i. The elements available in the nature that fulfill the basic needs of living things on

earth, thereby allowing life to sustain on earth are known as Natural Resources.

ii. Air, water and land are called the earth’s atmosphere, hydrosphere and lithosphere

respectively. iii. Living things and the parts of the lithosphere, hydrosphere and atmosphere which

they occupy are together called as biosphere (In Greek, bios = life,

sphaira = sphere).

2. Air:

i. Air in the atmosphere around the earth comprises of various gases such as nitrogen,

oxygen, carbon dioxide, six inert gases, nitrogen dioxide, sulphur dioxide, water

vapour and dust particles.

ii. Proportion of gases in air is as follows:

Spheres of Earth Proportion of gases

Troposphere 80% of the total mass of gases in the air

Stratosphere 19% of the total mass of gases in the air

Mesophere and Ionosphere Proportion of gas goes on decreasing

Exosphere Lacks gases completely

iii. Uses of the different gases in air are as follows:

Gas Uses

Nitrogen

Helps living things to build necessary proteins.

Useful in production of ammonia also, in food industry for air

tight packaging of food items.

Oxygen Essential for respiration (breathing in living things) and for

burning (combustion).

Carbon dioxide For photosynthesis (in plant) and is a major constituent of fire

extinguishers.

Argon Used in electric bulbs.

Helium Used for obtaining low temperature and for generating lift in

airships.

Neon Used in street lights and decorative lights.

Krypton Component of fluorescent tubes.

Xenon Used in flash photography.

iv. Atmosphere acts as an important filter, because:

a. It allows light and heat to reach earth’s surface in quantities required for life to

sustain on earth.

b. Also, it prevents harmful elements from reaching the earth.

v. Fog, clouds, snow and rain are produced in atmosphere.

vi. Air pollution: Any undesirable change in the normal composition of the air by

addition of harmful gases is known as air pollution.

1. Natural Resources : Air, Water and Land

Std. VI: General Science Workbook

2

vii. Air pollution is caused by harmful gases given out through combustion of fuels in

vehicles and in big industries. It is also caused due to incomplete combustion of fuels

like coal and wood.

viii. Nitrogen dioxide, carbon dioxide, carbon monoxide, sulphur dioxide and soot are

some harmful air pollutants.

3. Ozone layer:

i. Ozone layer is present in the lower part of the stratosphere.

ii. It functions as a shell to protect the earth from harmful ultra violet rays coming from

the sun.

iii. Chemical gases like Carbon tetrachloride, Chlorofluorocarbons used in air

conditioners and refrigerators mix with air and destroy ozone layer.

4. Water:

i. It is said that ‘Water is life’, because it is absolutely essential for survival of living

things.

ii. Water is colourless, tasteless and odourless. It is universal solvent (many substances

readily dissolves). It occurs in three states such as solid (ice), liquid (water) and

gaseous (water vapour).

iii. The blood of animals and sap in plants contain a very high proportion of water.

iv. Water available on earth:

a. Water in seas and oceans: 97%

b. Ground water, frozen state (ice): 2.7%

c. Fresh, drinking water: 0.3%

Thus, only 0.3% of total water covering the earth’s surface can be utilized for the purpose

of drinking.

5. Water cycle:

i. ‘Water cycle’ that leads to rainfall is the major source of water on earth.

ii. Water evaporates from the oceans, gets stored in the clouds and condenses as rain.

Thus, fresh water enters the ocean, thereby completing the cycle.

iii. Rain water also seeps into the ground, thereby increasing the ground water level.

This gives rise to other sources of water like rivers, ponds, springs, lakes, streams.

iv. Uncontrolled use of water for the ever increasing population, industry and farming

has resulted in shortage of water.

v. Thus, it is necessary to use water sparingly. Water can be percolated in the ground by

blocking it. Stored water does not become stale at once, thus it can be reused

wherever possible.

6. Land:

i. Land is seen in the form of stones, soil, big rocks.

Both plants and animals need land. Humans live on

land as well as utilize it for other purposes like

shelter, farming etc. Land is an important source of

minerals, crude oil and natural gas, which are useful

for humans in many ways.

ii. Layers of land:

a. Humus: Topmost mature layer. It is most

fertile layer formed by decomposition of

animals and plants.

Humus

Immature soil

Bedrock

Top soil

Layers of land

Layer of soil and

small rocks

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and Land

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Fill in the blanks

*1. The layer of ozone gas absorbs --------------------------------

rays that come from the sun to the

earth.

*2. Of the total water available on the earth, fresh water forms --------------------------------

percent.

*3. Both --------------------------------

and --------------------------------

constituents are present in the

soil.

Summative Assessment

Q

b. Top soil: Full of sand, soil, small stones, worms and insects.

c. Immature soil: Comprises of soil and pieces of bedrock.

d. Bed rock: A layer with less soil and more rocks. Minerals are obtained from this

layer. Responsible for colour and texture of the soil.

iii. Soil formation is slow, continuous and

natural process. It takes about a

thousand years for a 2.5 cm thick layer

of mature soil to form.

iv. Heat, cold and water breakdown the

bedrocks into pieces. From these

pieces stones, sand and soil particles

are formed.

v. Microbes, worms and insects as well as

rodents like mice and rats are found

here. Roots of trees also contribute in

weathering of rocks.

vi. Soil erosion occurs due to natural

calamities like earthquakes, fluids, storms and human activities such as mining,

farming and deforestation etc. It makes land barren.

vii. Thus, to prevent soil erosion, it is necessary to plant more trees, as the roots of

trees/plants/ grasses and bushes hold the soil particles tightly.

viii. Formation of fossil fuels: Geographical upheavals led to burial of the trees and

animals deep inside the land. Burial of the remains of plants and animals for many

ages led to formation of fossil fuels.

ix. Fossil fuel gives us many useful substances such as petrol, diesel, kerosene, paraffin,

tar and wax.

x. All living things utilize the natural resources for their survival but the availability of

natural resources in the environment is limited.

For example – Oxygen – 21%

Fresh water – 0.3%

Land – 29%

Thus, one need to use these resources judiciously.

xi. India Meteorological Department (IMD) was established in 1875 for studying the

weather in Indian subcontinent.

Stones, Sand,

Soil

Breaks down into

Rock

Wind Cold

Formation of

layer of soil

Microbes

Rodents

Roots of

plants

Heat Water


4

4. Atmosphere, hydrosphere and lithosphere constitute the --------------------------------

.

5. Gases are absent in --------------------------------

layer of atmosphere.

6. Fog, snow and rain are formed in --------------------------------

.

Right or Wrong ? If Wrong, write the correct sentence

*1. Land and soil are the same thing.

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*2. The water in a lake is called ground water.

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*3. It takes about 1000 years to form a 25 cm thick layer of soil.

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*4. Radon is used in decorative lights.

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5. Weathering of rock is the initial process of soil formation.

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6. Hydrosphere occupies 71% of the earth’s surface.

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7. The land on the earth’s surface is the ‘lithosphere’.

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8. Soil is formed by man-made process.

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Odd one out

1. Soot, nitrogen dioxide, carbon monoxide, oxygen, sulphur dioxide.

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2. Petrol, paraffin, diesel, kerosene, chlorofluorocarbon.

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� �Q

Q

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Match the Following

*1. Match the natural resources from Group ‘A’ with the related descriptions given in Group ‘B’.

Group ‘A’ Answer Group ‘B’

i. Carbon dioxide a. Generation of soil

ii. Oxygen b. Rain

iii. Water vapour c. Plants and food

production

iv. Microbes d. Combustion

2. Match the name of the gases from Group ‘A’ with their uses given in Group ‘B’.

Group ‘A’ Answer Group ‘B’

i. Xenon a. Used to obtain low

temperature

ii. Argon b. Used in fire

extinguishers

iii. Helium c. Used in electric bulbs

iv. Carbon dioxide d. Useful in agriculture

Answer in one word

1. Name the following

*i. Constituents of the biosphere ----------------------------

----------------------------

*ii. Biotic constituents of soil ----------------------------

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*iii. Fossil fuel ----------------------------

*iv. Inert gases in air ----------------------------

*v. Gases that are harmful to the ozone layer ----------------------------

vi. The topmost fertile natural layer of the soil. ----------------------------

vii. The process of destruction of fertile layer of soil by floods, storm and

human activities. ----------------------------

viii. The institute established for studying the weather changes and

making the forecasts about rainfall in the Indian subcontinent. ----------------------------

Q

Q


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Answer in your own words

*1. Explain with the help of a diagram how soil is formed.

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*2. Why is there a shortage of water even though it occupies about 71% of the earth’s surface?

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*3. What are the various constituents of air? Write their uses.

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*4. Why are air, water and land considered to be valuable natural resources?

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5. Can you tell? (Textbook pg. no. 5)

i. What is land made of?

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ii. Is land flat every where?

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iii. Does man produce soil / land?

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iv. If a deep pit is dug in the ground, what do you find there?

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Give reasons

1. Why is it said that …?

*i. The ozone layer is a protective shell of the earth.

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*ii. Water is life.

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*iii. Seawater is useful even though it is not potable.

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iv. Atmosphere is an important filter.

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Answer the following

1. What will happen if:

*i. Microbes in the soil get destroyed.

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*ii. The number of vehicles and factories in your surroundings increases.

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*iii. The total supply of potable water is finished.

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Open ended questions

1. Why is it said that individuals suffering from high blood pressure and asthma are advised not

to visit hill stations?

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2. What will happen if:

i. All the trees on the earth are cut.

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ii. Resources are not used judiciously.

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3. Use your brain power! (Textbook pg. no. 3)

What would have happened if there were no air on the earth?

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1. Which day is celebrated as ‘Ozone Protection Day’?

2. How much water do we need to drink per day for normal functioning of our day?

3. What is the proportion of humus is the layer of good fertile soil?

4. Tell any two uses of carbon dioxide.

Apply your knowledge

1. Observe (Textbook pg. no. 1)

Observe the figure given above and answer the following questions:

i. Where do we see the birds?

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ii. Where is the cow grazing?

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iii. Locate the trees and the road.

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iv. Where does the river come from? How does it flow?

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v. Where is the aeroplane?

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vi. Where are the fish seen?

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vii. On what is the sail boat floating?

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2. Can you recall? (Textbook pg. no. 2)

What are the five layers of the atmosphere?

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Oral Test

Formative Assessment

Q

Spheres of the earth

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Observe the figure given above. What is the similarity in the three pictures?

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5. Lets try this (Textbook pg. no. 4)

Observe how much water is used and for what purposes it is used in your house for a whole day.

Record it in a chart like the one shown below. Discuss this data in the class. Divide the total

amount of water used in your house by the number of persons to find out how much water each

person needs.

Purpose for which water is used Amount of water (approx. in litres)

Bath

Brushing teeth

Washing clothes and utensils

Mopping the floor

Drinking

Cooking

Total use of water

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6. Find out (Textbook pg. no. 4)

In what ways is the water in sea and oceans useful even though it is salty?

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Air pollution


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Observe the figure given above and answer

the following questions.

i. For which purposes is water being used?

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ii. Do other living things use water like we do?

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8. Can you tell? (Textbook pg. no. 5)

i. What do you see on land?

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Uses of water on the earth

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ii. What has man created on land?

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9. Use your brain power! (Textbook pg. no. 7)

What are the constituents of soil? Classify them as biotic and abiotic constituents.

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Activity/Project

1. Lets try this (Textbook pg. no. 6)

Perform the following activity

Take a transparent plastic bottle, a handful of soil, some stones, sand, some dry leaves and

water. Cut off the upper tapering part of the bottle. Put the rest of the materials in the lower

part and add water. Stir the mixture thoroughly and put it aside.

Observe it the next day and answer the following questions.

i. How does the mixture in the bottle look now?

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ii. Do you see layers in it?

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iii. What is seen in the different layers from top to bottom?

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Q


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2. Try this. (Textbook pg. no. 7)

Obtain specimens of soil from various places in your surroundings such as your own yard, a

garden, hills, river banks, fields and rocky ground. Note the differences in the specimens with

respect to colour, feel, texture and the size of the particles.

Type of soil

Characteristics Yard Garden Hills River Bank Fields

Rocky

ground

Colour

Texture

Size of particles

*3. Obtain detailed information about the work of the India Meteorological Department.

*4. Find a remedy for water scarcity.

Grades:

A - Excellent Teacher’s Remark:------------------------------------------------------------

B - Good ----------------------------------------------------------------------------------

C - Fair Date:--------------------

Sign:--------------------------

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