Green Science and Environment 6 Final (2076)

4. Magnetic Separation

Magnetic separation is the method in which magnetic substances are
separated from non-magnetic substances. In this method, a magnet is used.
The magnetic substances like iron, cobalt, nickel, etc. get attracted towards
magnet and hence they can be separated from non-magnetic substances.

Powdered ore

Magnetic Do You Know
Roller
The substances that are attracted towards
Magnetic belt magnet are called magnetic substances.
Examples: iron, cobalt, nickel, steel, etc.

Fig.Non-Magnetic substances
Fig. magnetic
10.7 substances

Activity 2
• Take some sand and mix small iron nails into it.

• Take a powerful magnet and separate iron nails from
the mixture.

5. Filtration Filter paper

Filtration is the method of separation Mixture of
of mixture in which the components solid and liquid
of the mixture are separated by Filter
using a filter paper or muslin cloth. funnel
This method is used to separate
the heterogeneous mixture of solid
particles and liquid.

In filtration, insolube solid particles 10.8 Filtrate
mixed in a liquid do not pass through

the filter paper but the liquid passes through it. So it is possible to separate

insolube solid particles mixed in a liquid. Filtration of tea leaves from tea is the

most common example of filtration.

GREEN Science and Environment Book-6 101

In science laboratory, a filter paper Do You Know
is folded and fitted in a glass funnel
while separating the components of In filtration, the clear liquid collected after
a mixture by filtration. The method filtration is called filtrate and the solid
of folding a filler paper is shown is particles deposited on filter paper is called
the given figure. residue.

Fig.10.9
Fig. Method of folding a filter paper for filtration

Activity 3

To demonstrate filtration by separating the mixture of mud and water.

Requirements : Stand, two beakers, glass rod, glass funnel, filter paper,
mixture of mud and water.

Procedure Beaker

• Take a beaker and prepare a
mixture of mud and water.

• Take a filter paper, fold it forming a Stand Mixture
cone and adjust it in a glass funnel. Funnel
Filter paper
• Arrange the apparatus as shown in
the given figure

• Pour the mixture of mud and water Beaker
gently in the funnel using a glass Filtrate
rod.

• Collect the filtrate into a beaker. 10.10

Observation : A clear liquid, i.e. filtrate passes through the filter paper
which is collected in a beaker and mud remains as a residue
on the filter paper.

Conclusion : In this way, filtration can be demonstrated by separating the
mixture of mud and water.

102 GREEN Science and Environment Book-6

Key Concepts
1. When two or more substances are brought together in any proportion,

the resulting mass is called mixture.

2. Homogeneous mixture is that mixture in which mixing components are
distributed uniformly and they cannot be seen with naked eyes.

3. Heterogeneous mixture is that mixture in which mixing components are
not distributed uniformly and can be seen with our naked eyes.

4. The substances that are mixed together to form a mixture are called
components of the mixture.

5. Sedimentation is the process of settling down of heavier components of
the mixture at the bottom of the vessel.

6. Decantation is the process in which the clear liquid is poured into another
vessel without disturbing this sediment.

7. Winnowing is the method of separating the mixture of heavy and light
particles with the help of air.

8. Sieving is the method of separating the mixture of solid particles of
different size with the help of a sieve.

9. Magnetic separation is the method in which magnetic substances are
separated from non-magnetic substances.

10. Filtration is the method of separation of mixture in which the components
of the mixture are separated by using a filter paper or muslin cloth.

Exercise

1. Tick (µ) the correct statement and cross (X) the incorrect one.
a. A mixture consists of two or more substances in a fixed proportion.

b. The mixture of sand and water is a heterogeneous mixture.

c. Mixture of different colours is used in painting.

d. The mixture of mud and water can be separated by filtration.

e. Sieving is used to separate the mixture of heavy and light
solid particles.

GREEN Science and Environment Book-6 103

2. Fill in the blanks using appropriate words.
a. When two or more substances are brought together in any proportion,
the resulting mass is called ................................

b. All the components of a mixture cannot be seen in a ..............................
mixture.

c. The process of settling down of heavy components at the bottom
is called ................................

d. ................................ paper is used in filtration.

e. The mixture of magnetic and non-magnetic substances can be
separated by ................................

3. Tick (µ) the best answer from the given alternatives.
a. Which of the following is a homogeneous mixture?

sugar and salt sugar and water

sand and water soil and water

b. Which of the following is a heterogeneous mixture?

salt and water milk and water

alcohol and water sand and milk

c. The mixture of husk and rice can be separated by .................................

sedimentation winnowing

filtration decantation

d. The pouring of the clear liquid into another container without
disturbing the sediment is called ..................................

sedimentation filtration

decantation sieving

104 GREEN Science and Environment Book-6

e. Which of the given mixture can be separated by magnetic separation?

sand and iron fillings sand and salt

sugar and salt rice and rice coats

4. Answer the following questions.
a. What is mixture? Give any two examples.
b. What are two types of mixtures? Name them.
c. What is a homogeneous mixture? Give any two examples.
d. Define heletrogeneous mixture with any two examples.
e. Write any four importance of mixture.
f. Name any four methods of separation of mixtures.
g. What are sedimentation and decantation? What types of mixtures
are separated by these methods?
h. What is winnowing? Name any two mixtures that can be separated
by this method.
i. What is sieving? What types of mixtures can be separated by this
method?
j. What is magnetic separation?
k. What is filtration? What types of mixtures can be separated by this
method.

5. Differentiate between:

a. Homogenous mixture and heterogeneous mixture

b. Sedimentation and Decantation

c. Winnowing and Sieving

6. Write down the suitable method for separating the components of each
of the given mixtures.

a. Sand and water b. Rice and rice coats

c. Soil and water d. Iron fillings and sand

7. Describe an activity to demonstrate sedimentation and decantation.
8. Describe an activity to demonstrate filtration.
9. How can we separate the mixture of mud and water? Explain in brief.

GREEN Science and Environment Book-6 105

UNIT Some Useful

11 Chemicals

Weighting Distribution (Approximate) Teaching periods : 5 Marks (in %): 1

Before You Begin

We use different types of chemical substances in our day to day life.
These chemical substances include common salt, sugar, vinegar,
phenyl, washing soda, baking soda, oil, ghee, etc. These chemicals are
used for various purposes. We use sugar in tea, coffee, sweets, etc. We
use washing soda to wash clothes. We use vinegar in pickles. We use
common salt to add flavour in food. We use phenyl to kill germs and
so on. Among many chemicals, we study about common salt, sugar,
ghee, chuk and baking soda in this unit.

Learning Objectives Syllabus

After completing the study of this unit, students will be able to: • Some useful chemicals
- introduction
i. introduce some useful chemicals (common salt, • Sources and uses of
sugar, ghee, chuk and baking soda) that are used in - common salt
our daily life. - sugar
- ghee
ii. explain the uses of common salt, sugar, gheee, chuk - chuk
and baking soda. - baking soda

Glossary: A dictionary of scientific/technical terms

goitre : a swelling of the throat caused by a disease of thyroid gland that occurs
due to lack of iodine in diet.
fatigue
diabetes : a feeling of being extremely tired
baking : a disease which occurs due to lack of insulin
viscous : the process of cooking using dry heat in an oven
: thick and sticky, not flowing freely

106 GREEN Science and Environment Book-6

Some Useful Chemicals

1. Common salt

The chemical name of common salt is sodium chloride (NaCl). It is used daily

in our foods to add flavour. Common salt is a white crystalline solid. It is salty
in taste.

We add common salt in pulse, vegetables, pickle and
other food items. Common salt is manufactured from

sea water by evaporation. Common salt is also found in

mines. Some amount of iodine is mixed in common salt
which is commonly known as iodized salt.
Fig.
Fig.Iodine is very essential for our body. It helps in healthy Salt
growth of children. It also protects us from goitre. 11.1
Iodine evaporates on heating as it has low boiling

point. Therefore, we should add iodized salt in food items just before serving.
Similarly, we should keep iodized salt in a closed container to preserve iodine.

Common salt is widely used in vegetables, pulses, pickle, meat and many

other food items. It is also used to preserve meat, fish, pickle, etc. It is used to

protect food items from being spoiled.

2. Sugar

Sugar is a very common sweetening agent. It is used in tea, coffee, sweets,
chocolates, cold drinks, etc. It is also used to preserve foods. Sugar is a white
crystalline solid. It is prepared from the sugarcane juice. Sugar beets are also
used to make sugar. To prepare sugarcane, the stems of sugarcane are collected
and washed. Then these stems are crushed to extract juice. The sugarcane juice
can be extracted by using traditional surgarcane Kol or modern machines
(Crushers). The juice is passed through sugarcane processing machines.
Finally, white solid crystals of sugar are obtained. Chemically, sugar is called
sucrose. It is also found in apple, pineapple, banana, mango, grapes, etc.

11.2 Sugar Sugar mill
Sugarcane

GREEN Science and Environment Book-6 107

Sugar is also found in our blood in the form of glucose. It provides energy
to our body. We feel weak and fatigue due to deficiency of glucose in our
body. Due to lack of insuline, our body cannot regulate the amount of sugar in
blood. As a result, sugar passes out of the body through urine. This condition
is known as diabetes or sugar disease.

3. Ghee

Ghee is a very common fatty substance

which is used in our daily life. Its

chemical name is triglyceride. It is

yellowish-white and slippery solid

or semi-solid substance. It can be
Fig.
Fig.obtained from the milk of cow, buffalo,

etc. Vegetable ghee is obtained from 11.3
the seeds of some plants like chiuri,
mustard, sunflower, etc. Animal Ghee Vanaspati Ghee

On the basis of source, ghee is of two types, viz. animal ghee and vegetable or
vanaspati ghee.

The ghee which is obtained from the milk of animals is called animal ghee and
the ghee obtained from the seeds of plants is called vanaspati ghee. First, the
seeds of plants are crushed to extract oil. Then the oil is changed into vanaspati
ghee by hydrogenation in industries.

During winter or cold days, ghee exists in solid state but in hot summer days,
ghee is found in semi-solid state. Ghee is a good source of fat for our body. It
provides energy to our body and makes our body smooth and fatty. Our body
absorbs different vitamins like vitamin A, D, E and K with the help of ghee. We
use ghee in foods and sweets.

4. Chuk

Chuk is a sour chemical substance which is obtained from sour fruits like
citrus, lemon, pamilo, pomegranate, bhogate (grape fruit), lime, etc. It is a
viscous (thick) fluid having black or brown colour.

11.4

Lemon Grapes Citrus fruit Pamilo

108 GREEN Science and Environment Book-6

The chemical name of chuk is citric acid. To get chuk, first of all, the juice of
sour fruits like citrus, lemon, etc. is extracted using a traditional Kol or modern
machine. Then the juice is boiled continuously for a long time till we get a
viscous fluid. Chuk is used in foods and pickles to add flavour. It is the main
source of vitamin C. Chuk is also used to preserve foods.

5. Baking soda

The chemical name of baking soda is sodium bicarbonate (NaHCO3). It is
widely used in bakeries to make bread soft and spongy. It is also used for
making cakes, biscuits and for making soft drinks like soda water.

Fig.

11.5 Bread Cake
Baking soda

While making bread, wheat flour, water and some amount of baking soda
are mixed to make semi-solid paste and the paste is left for a few hours. After
a few hours, the paste is used to make bread. From this paste soft, light and
spongy bread can be produced due to the presence of baking power.

Activity 1
• Name the different chemicals that are used at your home.
• Write down the main uses of these chemicals.

Key Concepts

1. The chemical name of common salt is sodium chloride (NaCl). It is used
daily in our foods to add the flavour. Common salt is a white crystalline
solid.

2. Iodine is very essential for our body. It helps in healthy growth of children.
It also protects us from goitre.

3. Sugar is a very common sweetening agent. It is used in tea, coffee, sweets,
chocolates, cold drinks, etc.

4. Ghee is a very common fatty substance which is used in our daily life. Its
chemical name is triglyceride.

GREEN Science and Environment Book-6 109

5. Chuk is a sour chemical substance which is obtained from sour fruits like
citrus, lemon, pamilo, pomegranate, bhogate (grape fruit), lime, etc.

6. Chuk is used in foods and pickles to add flavour. It is the main source of
vitamin C. Chuk is also used to preserve foods.

7. The chemical name of baking soda is sodium bicarbonate (NaHCO3). It is
widely used in bakeries to make bread soft and spongy.

Exercise

1. Tick (µ) the correct statement and cross (X) the incorrect one.
a. The chemical name of common salt is sodium chloride.

b. Iodine is not essential for our body.

c. Sugar provides energy to our body.

d. Vegetable oil is changed into vanaspati ghee by hydrogenation.

e. The taste of chuk is sour.

2. Fill in the blanks using appropriate words.
a. Common salt is manufactured from ................................
b. Chemical name of sugar is ................................
c. In our body, ................................ helps to absorbs vitamins.
d. ................................ is obtained from sour fruits.
e. ................................ is used in cakes, biscuits and breads.

3. Answer the following questions.
a. What is common salt? Write its chemical name.
b. Write any two uses of common salt.
c. What is sugar? How is it obtained?

110 GREEN Science and Environment Book-6

d. What is ghee? Write its chemical name.
e. Write down the major use of ghee.
f. What is chuk? Name any two sources of chuk.
g. What is baking soda? Write its chemical name.
h. Write down the major uses of baking soda.
i. Why is baking soda added in flour while making breads?
j. Write any two uses of chuk.
4. Differentiate between:
a. Chuk and Sugar
b. Common salt and Sugar
5. How is sugar prepared? Write in brief.
6. How is chuk prepared? Write in brief.

GREEN Science and Environment Book-6 111

UNIT Air

12

Weighting Distribution (Approximate) Teaching periods : 5 Marks (in %): 2

Before You Begin

Air is a mixture of different gases. The gases present in air include
nitrogen, oxygen, carbon dioxide, water vapour and inert gases like
neon, argon, etc. The layer of air that surrounds the earth's surface is
called atmosphere. Air is very essential for survival of living beings.
We can feel air but cannot see. Air has weight and occupies space.
It is a colourless, odourless and tasteless matter. Due to gravity. i.e.
pulling force of the earth, air flows from one place to another. Air
occupies space. So, all empty vessels remain filled with air. In this
unit, we will study about composition of air, physical properties and
uses of air.

Learning Objectives Syllabus
After completing the study of this unit, students will be able to:
i. introduce atmosphere and write its composition • Introduction to air

ii. state the properties and uses of air • Composition of air

iii. demonstrate some experiment related to air. • Experiments to describe the
properties of air
iv. describe the uses of some gases like nitrogen,
oxygen, carbon dioxide and water vapour. • Uses of air

• Brief introduction to nitrogen,
oxygen, carbon dioxide and
water vapour and their uses

Glossary: A dictionary of scientific/technical terms

air : the mixture of various gases like nitrogen, oxygen, carbon dioxide, water
vapour, etc.
combustion
expand : the process of burning some thing
rust
: to increase in size or volume
dispersal
droop : a reddish brown substance that forms on iron when it comes in contact
with moist air

: the process of spreading something over a wide area

: to bend, hang or move downwards

112 GREEN Science and Environment Book-6

Air

Composition of Air

The mixture of different gases like

nitrogen, oxygen, carbon dioxide, 21%
water vapour, neon, argon, etc. is oxygen gas

called air. About 78% of the air is g1%aseosther
occupied by nitrogen and 21% is

occupied by oxygen. Air consists Fig. 78%
of 0.03% of carbon dioxide and nitrogen gas

0.93% of argon, 0.002% of neon 12.1
and 0.02% of other gases. Air

also contains water vapour. However, the amount of water vapour present

in air varies from time to time and place to place. The pie-chart showing the

composition of air is given alongside.

The various gases present in air and their amount in percentage is tabulated below:

S.No. Gases present in air Volume (in %)
1 Nitrogen 78
2 Oxygen 21
3 Carbon dioxide 0.03
4 Argon 0.93
5 Neon 0.002
6 Other gases 0.02

1. Oxygen is present in Air

Oxygen occupies about 21% of the air by volume. It is the most important
gas for living beings because living beings use oxygen for breathing.
Oxygen also helps in combustion, i.e. burning of various substances. Plants
and animals cannot live without oxygen.

Activity 1

To demonstrate that oxygen is present in air
Requirements : Bell jar, porcelain basin, water trough, water, cork, match

box, phosphorus, marker
Procedure
• Take a water trough and put some water in it.
• Put some phosphorus in porcelain basin and place it on water in the water

trough. Cover the porcelain basin with a bell jar as shown in the figure.

GREEN Science and Environment Book-6 113

• Mark the level of water in the bell jar.

Water trough
Phosphorus
Porcelain basin

Fig. Water
Fig.
12.2

• Burn the phosphorus on the porcelain basin carefully and cover the
mouth of the bell jar immediately.

• Observe the level of water in the bell jar when the phosphorus burns
completely.

Water trough

Water
Water level
increase about
20% by volume
12.3

Observation : When the phosphorus burns completely the level of water
decreases initially due to expansion of air but the level of
water rises immediately.

In the bell jar, water level increases about 20% by volume.

Conclusion : From this experiment, it can be concluded that air contains
about 20% of oxygen.

2. Carbon dioxide is present in Air

Air contains about 0.03% of carbon dioxide by volume. Carbon dioxide is
used by green plants during photosynthesis. So, carbon dioxide is a very
important gas for living beings. This gas is also used for extinguishing fire.

Activity 2
To prove that air contains carbon dioxide gas

Requirements : A beaker, lime water, straw

114 GREEN Science and Environment Book-6

Procedure

• Take a beaker and put some lime water into the beaker. Observe whether
the lime water is clear or not.

• Take a straw and blow air into the lime water for a while. What do you
observe?

Straw

Beaker

Fig.
Clear lime Limewater
12.4 water turns milky

Observation : When air is blown into lime water for a while, the clear
solution of lime water turns milky.

The carbon dioxide present in the blown air reacts with lime
water and forms insoluble calcium carbonate. As a result,
lime water turns milky.

Conclusion : This experiment proves that air contains carbon dioxide.

3. Water vapour is present in air

When water is heated, it changes into vapour. Vapour is the gaseous state
of water. We can observe moisture and fog in air. These are examples of
water vapour present in atmosphere. Water vapour makes air humid. The
amount of water vapour present in air varies from time to time and place
to place.

Activity 3

To demonstrate that air contains water vapour

Requirements : A steel glass, card board, some ice-cubes

Procedure

• Take a steel glass and put some ice-cubes into it.

• Cover the mouth of the glass with a card board so that no water comes
out of the glass.

GREEN Science and Environment Book-6 115

• Wipe the outer surface of the glass so that no water remains on the surface.
• Leave the glass on a table for 5 to 10 minutes. Then observe the outer

surface of the glass.

Card board

No waterFig.Ice cubes Water
droplets droplets
12.5
After 5-10 minutes

Observation : Water droplets can be seen on the outer surface of the glass
after a few minutes. Due to presence of ice cubes, the outer
surface of the glass becomes very cold. When the water
vapour present in air comes in contact of the colder surface
of the glass, it condenses into water droplets.

Conclusion : From this experiment, it can be concluded that air contains
water vapour.

Physical properties of air

1. Air is colourless, odourless and tasteless.
2. It expands on heating and contracts on cooling.
3. It has weight.
4. It occupies space.
5. It flows from one place to another.
6. It exerts pressure.
7. It can be compressed.
8. It is a mixture of various gases like nitrogen, oxygen, carbon dioxide, etc.

Activity 4
To demonstrate that air has weight
Requirements : Two large balloons of equal size, a straight wooden stick,

pin, threads

116 GREEN Science and Environment Book-6

Procedure
• Take two large balloons and inflate them with equal amount of air.
• Tie them with a thread.
• Take a straight wooden stick and find its mid-point.
• Tie a thread at the mid-point of the stick.
• Tie both balloons as shown in the figure (a) both balloons shown are of

the same weight.
• Now, take a pin and prick one of the balloons. What do you observe?

Fig.

12.6 (a) (b)

Observation : When one of the balloons is pricked, air rushes out of the
balloon and the balloon moves upwards and another balloon
moves downwards due to imbalance in weight. The inflated
balloon becomes heavier due to the presence of air inside it
and moves downwards.

Conclusion : From this experiment, it can be concluded that air has weight.

Rust and Rusting

Rust is a reddish-brown layer on the surface of iron kept on a moist place. The
process of formation of a reddish-brown layer on the surface of iron kept in a
moist place is called rusting. The chemical reaction involved in rusting is given
below:

4Fe + 3O2 water 2Fe2O3.xH2O (Rust)
vapour

Activity 4
To demonstrate rusting on iron
Requirements : Iron nails

GREEN Science and Environment Book-6 117

Procedure

• Take some iron nails and keep them in
a moist place.

• Leave the nails in the moist place for a Fig.
few days.

• Observe the nails after 2-3 days. 12.7

Observation : A reddish-brown

substance can be seen on the nails after 2-3 days.

The reddish-brown substance that can be seen on the outer
surface of nails is called rust and the process is called rusting.

Conclusion : From this experiment, we can demonstrate that rusting
occurs in the presence of moisture.

Uses of air

1. The oxygen present in air is used by all living beings for breathing.
2. Green plants use carbon dioxide for photosynthesis.
3. Nitrogen is used by green plants for photosynthesis.
4. Air is used to run windmills.
5. Air helps in seed dispersal.
6. Air is used to inflate tyres of vehicles.
7. Air is used to inflate balloons.

Some Important Gases Present in Air

1. Nitrogen

The molecular formula of nitrogen is N2. Among different gases present in
atmosphere, nitrogen occupies about 79% by volume. Nitrogen is a neutral
gas which does not react with other gases present in the atmosphere under
normal condition. Nitrogen is a very important gas for living organisms as it
is essential for protein synthesis.

Uses of nitrogen
1. Nitrogen helps in growth and development of plants.
2. It is used to protect food from spoiling.

118 GREEN Science and Environment Book-6

3. It is used for filling in high temperature gas thermometers.
4. It is used to fill in electric bulbs to provide inert atmosphere.
5. It is used to fill in fuel tanks of aeroplanes.
6. It is used for making ammonia, nitric acid, chemical fertilizers, etc.
7. In plants, nitrogen is used to synthesize protein, protoplasm and

chlorophyll.

2. Oxygen

The molecular formula of oxygen is O2. It is the most important gas for living
beings because all living beings need oxygen for breathing. Oxygen occupies
about 21% of the air by volume. Oxygen is an active gas as it combines with
other elements and forms various compounds.

Uses of oxygen
1. Oxygen is used by all living beings for breathing.

2. It is used for combustion, i.e. burning of various substances.

3. It is used for making oxy-hydrogen flame for cutting and welding of
metals.

4. It is used by deep sea divers and mountaineers for artificial breathing.

5. It is used in hospitals for artificial breathing.

3. Carbon dioxide

The molecular formula of carbon dioxide is CO2. It is another essential gas for
living beings as it is for green plants for photosynthesis. This gas consists of
one atom of carbon and two atoms of oxygen. This gas occupies about 0.03%
by volume. Green plants use carbon dioxide for making food. The process of
making food by green plants is called photosynthesis. All animals depend on
plants to obtain food. Therefore, no organisms can survive in the absence of
carbon dioxide.

Uses of carbon dioxide Do You Know
1. Carbon dioxide is used by green
The solid form of carbon dioxide is called
plants for photosynthesis. dry ice.
When carbon dioxide is cooled at about
2. It is used to make chemical –78°C, dry ice is formed. It is used as a
fertilizers like urea. cooling agent.

GREEN Science and Environment Book-6 119

3. It is used for making soft drinks like coke, beer, dew, sprite, etc.
4. It is used for extinguishing fire.
5. It is used for making dry ice.

4. Water vapour

Water vapour is the gaseous form of water. It makes air humid. The amount of
water vapour in atmosphere varies from place to place and from time to time.
The amount of water vapour present in the atmosphere is called humidity.
Humidity in air is important for living beings.

Uses of water vapour
1. Water vapour protects animals from dying.
2. It protects plants from drooping.
3. It retains moisture in the atmosphere.
4. It retains freshness in vegetables.

Key Concepts
1. The mixture of different gases like nitrogen, oxygen, carbon dioxide,

water vapour, neon, argon, etc. is called air.
2. Rust is a reddish-brown layer on the surface of iron kept on a moist place.

The process of formation of a reddish-brown layer on the surface of iron
kept in a moist place is called rusting.
3. Nitrogen is a neutral gas which does not react with other gases present in
the atmosphere under normal condition.
4. It is the most important gas for living beings because all living beings
need oxygen for breathing.
5. The process of making food by green plants is called photosynthesis.
6. Water vapour is the gaseous from of water.
7. The amount of water vapour present in the atmosphere is called
humidity.

120 GREEN Science and Environment Book-6

Exercise

1. Tick (µ) the correct statement and cross (X) the incorrect one.
a. Air is a mixture of different gases.
b. About 78% of oxygen is found in air.
c. Air has weight and occupies space.
d. Nitrogen is essential for photosynthesis.
e. Carbon dioxide is used for extinguishing fire.

2. Fill in the blanks using appropriate words.
a. ................................ gas occupies about 79% of air by volume.
b. Living beings use ................................ gas for breathing.
c. Air is colourless, ................................ and .................................
d. ................................ gas is filled in fuel tanks of aeroplanes.
e. ................................ gas is used for making fire extinguishers.

3. Tick (µ) the best answer from the given alternatives.
a. The mixture of different gases is called ...........................

water land air soil

b. ........................... gas occupies about 0.03% of air by volume.

oxygen nitrogen argon carbon dioxide

c. Which of the following gases is filled in electric bulbs?

oxygen nitrogen hydrogen carbon dioxide

d. Which of the given gases is used for photosynthesis?

CO2 O2 N2 Ne

GREEN Science and Environment Book-6 121

4. Answer the following questions.
a. What is air? Name the different gases present in the atmosphere.
b. Write down the physical properties of air.
c. Write down the major uses of air.
d. Define rust and rusting.
e. Write the conditions required for rusting.
f. Write down any four uses of nitrogen gas.
g. What is the percentage of oxygen in air? Write any three uses of
oxygen.
h. What is the percentage of carbon dioxide in air? Write down the
major uses of carbon dioxide.
i. What is dry ice? Write its major use.
j. What is meant by humidity? Write any two uses of water vapour.

5. Describe an experiment to prove that air contains oxygen.
6. Describe an experiment to prove that air contains carbon dioxide.
7. Describe an experiment to prove that air contains water vapour.
8. Describe an activity to demonstrate that air has weight.

122 GREEN Science and Environment Book-6

UNIT Metals

13

Weighting Distribution (Approximate) Teaching periods : 3 Marks (in %): 1

Before You Begin

We use various types of materials in our daily life. These materials
may be metals, non-metals or mettalloids. Iron, copper, silver, gold,
aluminium, etc. are the examples of metals. They are good conductors
of heat and electricity. They are malleable and ductile. Metals are
widely used in our daily life for various purposes. Metals are those
elements which conduct heat and electricity. Carbon, chlorine,
nitrogen, oxygen, sulphur, phosphorus, etc. are the examples of
non-metals. They are bad conductor of heat and electricity. They are
neither malleable nor ductile. Non-metals are these elements which do
not conduct heat and electricity. Metalloids are those elements which
show properties of both metals and non-metals. Silicon, germanium,
arsenic, antimony, etc. are the examples of metalloids. In this unit, we
will study about metals, non-metals and metalloids in brief.

Learning Objectives Syllabus

After completing the study of this unit, students will be able to: • Introduction to metals, non-
i. introduce metals, non-metals and metalloids with metals and metalloids

examples. • Characteristics of metals, non-
metals and metalloids
ii. state the characteristics and uses of metals, non-
metals and metalloids. • Some activities related to
metals
iii. state the uses of some common metals (gold, silver,
copper and iron) • Uses of metals, non-metals
and metalloids

• Some common metals (gold,
silver, copper and iron) and
their uses

Glossary: A dictionary of scientific/technical terms

metals : the elements having conductivity, malleability and ductility
conductivity : the property of a substance due to which it conducts heat and electricity
malleablity : the property of a substance due to which it can be beaten into a thin sheet
ductility : the property of a substance due to which it can be drawn into a thin wire
metalloid : the substance which shows properties of both metals and non-metals
lustre : the shining quality of a surface

GREEN Science and Environment Book-6 123

Metals

We use various materials like cooking utensils, weapons, ornaments, electric
wires, etc. These materials are made of metals. Iron, aluminium, copper, silver,
gold, calcium, magnesium, platinum, etc. are examples of good metals. They
are conductor of heat and electricity. They are malleable and ductile. So, metals
are the elements having conductivity, malleability and ductility.

Fig.

13.1 Silver Gold
Iron Aluminium Copper

Characteristics of metals

1. Metals are good conductor of heat and electricity.
2. Most metals exist in solid state in room temperature except mercury,

caesium and gallium.
3. They are malleable, i.e. they can be converted into thin sheets on beating.
4. They are ductile, i.e. they can be changed into long wires.
5. They have high melting point and boiling point.
6. Most metals are hard except lithium, sodium and potassium.
7. They are lustrous, i.e. shiny in nature.
8. They are sonours in nature. It means metals produce tinkling sound on

heating.

1. Metals are good conductor of heat

Metals are good conductor of heat. So we use metals for making cooking
utensils. They conduct heat from one part to another. There fore, we should
not touch cooking utensils while they are heated as they burn our skin.

Experiment 1

To demonstrate that metals are good conductor and non-metals are bad
conductor of heat.

Requirements : Bunsen burner, spirit lamp or a candle, match box, an iron
rod, a wooden stick

124 GREEN Science and Environment Book-6

Procedure

• Take an iron rod and a wooden stick of the same shape and size.

• Heat the one end of iron rod with a burner/ spirit lamp/ candle for a few
minutes and catch the other end of the rod. Repeat the same process for
wooden stick.

Observation : The outer end of the iron rod is felt hot when heated for a
few minutes but the outer end of wooden stick is not felt
hot. Iron is good conductor of heat. So when one end of iron
rod is heated for a while its another end is felt hot due to
conduction of heat. But wood is bad conductor of heat, it
does not conduct heat from one end to another. So another
end of wooden stick is not felt hot.

Wooden stick Iron rod

Fig.

13.2

Conclusion : From this experiment, it can be concluded that metals are
good conductor and non-metals are bad conductor of heat.

2. Metals are good conductor of electricity
We use metals like copper, aluminium, etc. for making electric wires as

they conduct electricity. All metals conduct electricity from one end to
another. Therefore, metals are used for making electric wires and electrical
equipment.

Experiment 2
To demonstrate that metals are good conductor and non-metals are bad
conductor of electricity.
Requirements : Battery, electric bulb, copper wire, coin, a piece of wood,

rubber, a piece of plastic, a piece of blade

GREEN Science and Environment Book-6 125

Procedure

• Take a battery, an electric bulb and pieces of copper wire

• Assemble an open circuit as shown in the figure.

• Leave the gap PQ in the circuit.

• Place a coin, to connect the ends of wire PQ. What do you observe? Does
the bulb glow? Why?

• Remove the coin and repeat this activity by using a piece of wood, rubber,
a piece of plastic, a piece of blade, etc. one by one.

Bulb glows Bulb does not glow
PQ PQ
Coin (Conductor)
Wood (insulator)

Fig.

13.3 Battery

Observation : When the circuit is completed by using metal objects (coin,
piece of copper wire, coin, iron, etc.) the bulb glows but the
bulb does not glow when circuit is completed with non-
metals (wood, rubber, plastic, etc.). It shows that metals
are good conductors and non-metals are bad conductors of
electricity.

Conclusion : From this experiment, it can be concluded that metals are
good conductor and non-metals are bad conductor of
electricity.

3. Metals are malleable and ductile Do You Know

Metals are malleable in nature. Metals are ductile and good conductor
It means that metals can be of electricity. Therefore, they are used for

converted into thin sheets by making electric wires.

hammering. Similarly, metals can

be drawn into thin and long wires

after heating. This property shows metals are ductile in nature.

Due to malleability, metals are suitable for making cooking utensils, sheets
and different types of containers. Due to ductility, they are suitable for
making electric wires.

126 GREEN Science and Environment Book-6

Experiment 3
To demonstrate that metals are malleable and non-metals are non-malleable.
Requirements : Hammer, a thick copper wire, a thick iron wire, a piece of

brick, a piece of stone
Procedure
• Take a thick wire of iron and hit it several times with a hammer. Now,

take a piece of brick and hammer it. What do you observe?
• Repeat this activity with a thick wire of copper and a piece of stone. What

do you observe?
Observation : Copper wire and iron wire become flat on hammering but

they do not break down into pieces. It shows that metals are
malleable. On other hand, brick and stone break down into
many small pieces on hammering. It shows that non-metals
are non-malleable.
Conclusion : From this experiment, it can be concluded that metals are
malleable and non-metals are non-malleable.

4. Metals are lustrous

Metals are shiny. They reflect light and shine brightly. The property of
metals due to which they appear smooth and shine brightly is called lustre.
Non-metals do not have lustre.

Experiment 4
To demonstrate that metals are lustrous and non-metals are non-lustrous.
Requirements : steel plate, wooden board, cardboard paper,
Procedure :
• Take a steel plate and reflect the sunlight using the plate.
• Repeat this activity with wooden board and cardboard paper one by one.

What do you observe? Which object appears shiny? Why?
Observation : Steel plate appears shiny and reflects light. But the wooden

board and cardboard paper do not reflect light. It shows that
steel plate is lustrous but wooden board and cardboard are
non-lustrous.

GREEN Science and Environment Book-6 127

5. Metals are usually hard
Most metals are hard and strong but some metals like lithium, sodium,

potassium, etc. are soft and weak. Metals like iron, copper, aluminium,
silver, etc. are soft and weak.

6. Metals are sonorous
Most metals are sonorous because they produce tinkling sound on heating.

On the other hand, non-metals do not produce tinkling sound on heating.
So they are non-sonorous in nature.

Experiment 5
To demonstrate that metals are sonorous and non-metals are non-sonorous.
Requirements : A hammer, a bell, steel plate, wooden block, brick
Procedure
• Take a hammer and hit a bell, steel plate, wooden block, brick one by one.
• Observe which object produces tinkling sound while hammering. Is there

any difference between the sound produced by metals and non-metals
when they are hammered? What do you observe?
Observation : The metal articles (bell, steel plate) produce tinkling sound

and non-metals (wooden block, brick) do not produce
tinkling sound on hammering. It shows that metals are
sonorous and non-metals are non-sonorous.
Conclusion From this experiment, it can be concluded that metals are
sonorous and non-metals are non-sonorous.

Uses of Metals

1. Metals are used in industries for making engines, machines, equipment,
etc.

2. Metals are used for making household utensils.
3. Metals are used for making rods, pipes, nuts, bolts, etc.
4. Metals are used for making parts and accessories of vehicles and machines.
5. Metals are used for making electric cables and wires.
6. Metals are used for making coins, crowns, vases and other decorative

items.

128 GREEN Science and Environment Book-6

7. Precious and expensive metals like gold and silver are used for making
ornaments.

8. Metal foils, e.g. aluminium foil is used for wrapping foods and medicines.

9. Liquid metal, i.e. mercury is used as a thermometric liquid.

Non-metals

Elements like carbon, chlorine, phosphorus, sulphur, iodine, etc. are called
non-metals. They are bad conductor of heat and electricity. They are non-
malleable, bad non-ductile and non-sonorous in nature. Non-metals are the
elements which do not have malleability and ductility.

Fig.

13.4

Carbon Iodine Sulphur Diamond

The characteristics of non-metals are as follows.

1. Non-metals are bad conductor of heat and electricity.

2. They are non-malleable. It means that non-metals cannot be changed into
thin sheets on hammering.

3. They are non-ductile. It means that non-metals cannot be drawn into long
wires.

4. They are non-lustrous except diamond and iodine.

5. They are non-sonourous. It means that non-metals do not produce tinkling
sound on hitting.

6. They are found in all three states, viz. solid, liquid and gas.

Uses of Non-metals

1. Non-metals are used to make utensils, parts of automobiles, construction
materials, fabrics, etc.

2. They are used to make insulators of electric equipment and wires as they
are bad conductors of electricity.

GREEN Science and Environment Book-6 129

3. They are used to make handles of corking utensils as they are bad
conductors of heat.

4. They are used as fuels.

5. Hydrogen is used to fill in balloons and as a fuel in rockets.

6. Oxygen is used for breathing and burning substances.

7. Sulphur is used for making fire crackers and explosives.

8. Chlorine is used for making medicines.

9. Diamond is used for making valuable gems.

10. Graphite is used for making lead of pencils and lubricant.

Metalloids

Metalloids are those elements that show the properties of both metals and non-
metals. Silicon, arsenic, germanium, antimony, etc. are examples of metalloids.
Some properties of metalloids are similar to metals and other are similar to
non-metals. So, metalloids lie in between metals and non-metals.

Fig.

13.5 Arsenic Germanium
Silicon

Properties of metalloids

1. They show characteristies of both metals and non-metals.
2. They are poor conductor of heat and electricity.
3. They are less malleable.
4. They are non-ductile.
5. They are lustrous.
6. They are non-sonorous.

130 GREEN Science and Environment Book-6

Differences between metals and non-metals

Metals Non-metals

1. Metals are good conductor of 1. Non-metals are bad conductor
heat and electricity. of heat and electricity except
graphite.
2. They are malleable.
2. They are non-malleable.

3. They are ductile. 3. They are non-ductile.

4. Most metals exist in solid state. 4. They exist in solid, liquid and
gaseous state.

5. They are lustrous. 5. They are non-lustrous except
iodine and diamond.

6. They are sonorous. 6. They are non-sonorous.

7. Most metals are hard. 7. Most non-metals are soft except
diamond.

Some Common Metals of Daily Use

1. Gold

Gold is a very expensive metal of shiny yellow colour. It is found in pure
state in nature as it does not react with air, water, moisture, acid, base and
other chemicals at normal conditions. It can be extracted from quartz veins
or sandy alluvial soil.

Fig.

13.6 Gold ornaments
Gold

Gold is highly malleable and ductile. Rusting does not occur in gold. So
it is suitable for making jeweleries. Gold is a good conductor of heat and
electricity. It is a very heavy metal.

GREEN Science and Environment Book-6 131

Uses

1. Gold is used for making expensive jewelleries.

2. It is used for making medals.

3. It is used for making statues and coins.

4. It is used for making medicines.

5. It is used for filling teeth.

6. It is used for gold plating.

7. It is used in photography.

2. Silver

Silver is a shiny white metal which occurs in free as well as in combined
state in nature. In combined state, silver is found in the form of chloride and
sulphide ores. Silver is extracted from argentite ore. It is the best conductor
of heat and electricity. It is a very less reactive metal. Rusting does not
occur in silver. Silver is highly malleable and ductile. So it is suitable for
making ornaments, medals, coins, etc.

Fig.

13.7 Silver coins
Silver

Uses

1. Silver is used for making jeweleries.
2. It is used for making coins.
3. It is used for making medals and statues.
4. It is used in photography.
5. It is used for filling teeth.
6. It is used for making mirrors.

132 GREEN Science and Environment Book-6

3. Copper

Copper is a reddish-brown Do You Know

metal. It is a very good conductor Copper is the second best conductor of
of heat and electricity. It is highly electricity after silver. It is cheaper than
malleable and ductile. Rusting silver. So, copper is widely used for making
does not occur on copper at electric wires and electric equipment.

ordinary condition. However,

copper turns black when kept in moist place for a long time. Copper is

used to make brass by mixing it with zinc. Copper is being used in Nepal

from ancient times.

Copper is found in combined state in nature. It is extracted from
chalcopyrite, cuprite, etc.

Fig.

13.8 Copper utensils
Copper

Uses

1. Copper is used for making household utensils.
2. It is used for making electric wires.
3. It is used for making coins and idols.
4. It is used for making sculptures and statues.
5. It is used for making insecticides and germicides.
6. It is used for making electrical and electronic equipment.
7. It is used for making alloys like brass, bronze, bell metal, etc.

4. Iron

Iron is a grayish-white metal which is widely used in the field of construction
and industries. It is a reactive metal. So it is not found in pure state or
free state in nature. It is extracted from haematite and magnetite ores. It is

GREEN Science and Environment Book-6 133

malleable and ductile. It is a good conductor of heat and electricity. Rusting
takes place in the iron kept in a moist place. Iron forms various compounds
like oxides, hydroxides, chlorides, carbonates, etc. Some amount of iron is
also found in the haemoglobin of blood.

Fig.

13.9 Materials made of iron
Iron

Uses

1. Iron is used for making rods, pipes, nuts, bolts, etc.
2. It is used for making household utensils.
3. It is used for making buildings, roads, bridges, parts of vehicles, engines,

machines, etc.
4. It is used for making furniture, weapons, tools, etc.
5. It is used for making railway tracks.
6. It is used for manufacturing steel.
7. It is used as a catalyst in various chemical reactions.

Experiment 1

Prepare a list of various metals, non-metals and metalloids that are used at
your homes. Also, write their uses in the given table.

S.No. Metals Uses

134 GREEN Science and Environment Book-6

S.No. Non-metals Uses

S.No. Metalloids Uses

Key Concepts

1. Metals are the elements having conductivity, malleability and ductility.
2. We use metals like copper, aluminium, etc. for making electric wires as

they conduct electricity.
3. Metals are malleable in nature. It means that metals can be converted into

thin sheets by hammering.
4. Metals are shiny. They reflect light and shine brightly.
5. Non-metals are the elements which do not have malleability and ductility.
6. Metalloids are those elements that show the properties of both metals

and non-metals.
7. Gold is a very expensive metal of shiny yellow colour.
8. Silver is a shiny white metal which occurs in free as well as in combined

state in nature.
9. Copper is a reddish-brown metal. It is a very good conductor of heat and

electricity.
10. Iron is a grayish-white metal which is widely used in the field of

construction and industries.

GREEN Science and Environment Book-6 135

Exercise

1. Tick (µ) the correct statement and cross (×) the incorrect one.
a. Metals conduct heat and electricity.
b. Non-metals are lustrous.
c. Copper and iron are examples of metalloids.
d. Rusting does not occur on silver and gold.
e. The colour of copper is greyish-white.

2. Fill in the blanks using appropriate words.
a. ................................ are malleable and ductile.
b. Non-metals do not conduct heat and ................................
c. ................................ is a shiny yellow metal.
d. Silicon and arsenic are ................................
e. ................................ is found in quartz veins and sandy alluvial soil.

3. Tick (µ) the best answer from the given alternatives.
a. ........................... are malleable and ductile.

metals non-metals

metalloids elements

b. Which of the following elements is a non-metal

silver chlorine gold iron

c. Which of the given elements shows the properties of both metals and
non-metals?

oxygen carbon silicon copper

d. Which of the given element is the best conductor of electricity?

gold silver copper iron

e. Which of the given element undergoes rusting?

silver iron copper gold

136 GREEN Science and Environment Book-6

4. Answer the following questions.

a. What are metals? Give any five examples.
b. Write any five properties of metals.
c. Write any five uses of metals.
d. What are non-metals? Give any three examples.
e. Write any five properties of non-metals.
f. Write any five uses of non-metals.
g. Where is gold found in nature? Write any three properties of gold.
h. Write any three properties of silver and copper.
i. Name the ores from which iron can be extracted. Write any three

properties of iron.
j. Which metals are used for filling teeth?

5. Differentiate between: b. Non-metals and Metalloids
a. Metals and Non-metals
c. Copper and Gold

6. Write any four uses of each of the given metals.

a. Gold b. Silver

c. Copper d. Iron

7. Give reason.
a. Gold and silver are called metals.
b. Iron and copper are used for making cooking utensils.
c. Silicon is called a metalloid.
d. Chlorine and iodine are called non-metals.
e. Gold is used for making jewelleries.

8. Describe an activity to show that metals are good conductor and non-
metals are bad conductor of electricity.

9. Describe an activity to show that metals are malleable and non-metals
are non-malleable.

10. Describe an activity to demonstrate that metals are sonorous in nature.

GREEN Science and Environment Book-6 137

Biology

UNIT Living Beings

14

Weighting Distribution (Approximate) Teaching periods : 8 Marks (in %): 1

Before You Begin

The things having life are called living things. They include
different types of plants and animals. Lotus, rose, spirogyra,
grass, crops, fruits, vegetables, insects, birds, fishes, snakes, etc.
are examples of living beings. Growth, reproduction, respiration,
digestion, excretion, etc. are the basic properties of living beings.
Living beings are broadly classified into plants and animals. They
may be unicellular or multicellular and aquatic or terrestrial. In
this unit, we will study about living beings in brief.

Learning Objectives Syllabus

After completing the study of this unit, students will be able to: • Introduction to living beings
i. introduce living beings and differentiate between
• Differences between plants
plants and animals. and animals.

ii. classify animals on the basis of adaptational • Classification of animals on
characteristics. the basis of adaptational
characteristics
iii. classify plants on the basis of habitat and life span.
• Aquatic animals and
iv. introduce monocot and dicot plants and differentiate terrestrial animals
between them.
• Classification of plants on the
basis of habitat

• Aquatic plants and terrestrial
plants. Classification of plants
on the basis of life span

• Monocotyledonous and
dicotyledonous plants

Glossary: A dictionary of scientific/technical terms

habitat : a place where living beings live and reproduce
hump : a large lump on the back of camel
arboreal : relating to tree, living in trees
submerge : to go under the surface of water
biennial : any plant that lives for two years
perennial : any plant that lives for more than two years

138 GREEN Science and Environment Book-6

Living Beings

The things having life are called living beings. Different types of plants and
animals found around us are called living beings.

Mushroom Fern Rose Mango

Fig.

14.1 Octopus Fish Panda
Snail

Living beings are broadly classified into the Plant Kingdom and the Animal
Kingdom. The Plant Kingdom includes different types of plants like spirogyra,
mushroom, moss, fern, cycas, maize, grass, mango, orange, etc. Both flowering
plants and non-flowering plants are kept in the Plant Kingdom. The Animal
Kingdom includes different types of animals like amoeba, hydra, tapeworm,
butterfly, roundworm, earthworm, snail, starfish, fishes, frogs, snakes, birds,
mammals, etc.

Animals and plants are found in different habitat and climatic conditions.
They have different structures and characteristics according to their habitat.
The living beings that live in water differ from the living beings that live on
land. Similarly, the living beings that live in cold places are different from
those that live in hot places.

Activity 1

Observe any five plants and five animals in your locality.

Study their characteristics and find out the differences between plants
and animals.

GREEN Science and Environment Book-6 139

Difference between Plants and Animals

Plants Animals

1. Plants have cell wall in their cells. 1. Cell wall is absent in their cells.

2. Most plants can prepare their 2. Animals cannot prepare their

own food by photosynthesis. own food. They depend on green

plants to get food.

3. Most plants have green pigment 3. Animals do not have chlorophyll.
cell chlorophyll.

4. Most plants do not move from 4. Most animals move from one

one place to another. place to another.

5. Most plants grow throughout 5. Most animals do not grow

their life. throughout their life.

6. Plants do not have sense organs. 6. Most animals have sense organs.

Classification of Animals

Animals are classified into two main groups on the basis of habitat. They are

1. Aquatic animals 2. Terrestrial animals

1. Aquatic Animals

Different types of animals like fish hydra, octopus, starfish, shark, dolphin,
etc. live in water. These animals are called aquatic animals.

Characteristics Do You Know

1. Aquatic animals have boat- The animals that live in water are called
shaped or streamlined body. aquatic animals. Examples: fish, shark,
octopus, starfish, whale, dolphin, etc.
2. Their body is covered with
smooth and slippery scales or
mucous coat.

3. Most aquatic animals breathe through gills.

4. They have fins or webbed-feet for swimming in water.

5. They reproduce by laying eggs.

Fig.

14.2 Fish Shark
Octopus

140 GREEN Science and Environment Book-6

Fig. Fig.14.3 Whale Sea horse
Dolphin

2. Terrestrial Animals

Animals like cow, buffalo, dog, rabbit, grasshopper, snake, etc. live on
land. These animals are terrestrial animals. The animals that live on land
are called terrestrial animals. Some terrestrial animals are given below:

Zebra Dog Rabbit Panda

14.4 Cow Lion
Elephant

Terrestrial animals are divided into following groups on the basis of their
habitat.

a. Animals that live in cold and hot places

b. Animals that live in air

c. Animals that live in burrows

d. Animals that live on trees

GREEN Science and Environment Book-6 141

a. Animals that live on cold and hot places

On the basis of habitat, terrestrial animals have modified their bodies.
They have special features in their bodies to adjust in their habitat. Some
animals like yak, snow leopard, blue sheep, polar bear, panda, Himalayan
bear, etc. are found in cold places and animals like elephant, rhinoceros,
buffalo, tiger, etc. are found in hot places. The major characteristics of the
animals that live in cold and hot places are given below:

1. The animals that live in cold places have thick and long hair in their
bodies to prevent them from cold. On the other hand the animals that
live in hot places have thin and short hair in their bodies.

Fig. Fig.12.5 Polar bear Elephant Rhino
Yak

2. The animals of cold places like yak, snow leopard, polar bear, etc.

have a thick layer of fat under their skin. It helps to protect them from

extreme cold.

3. Some animals like cow, buffalo, sheep, goat, etc. have bilobed hooves
for walking properly whereas animals like horse, donkey, zebra, etc.
have unilobed hooves.

12.6 Horse Donkey Zebra
Buffalo

4. Carnivorous animals like tiger, lion, leopard, cat, etc. have strong

fore limbs with sharp and pointed claws. These structures help them
to catch their prey. These animals have sharp and pointed canines
adapted for tearing flesh.

142 GREEN Science and Environment Book-6

12.7 Fig.Paws of lionCannies of tiger Cannies of lion
Paws of tigerFig. Fig.

5. Desert animals like camel, etc. have
special tissues in their bodies to store
food and water. Camel has a hump on
its back which stores food in the form
of fat.

12.8

Camel

6. Animals like cow, buffalo, sheep and deer have horns for protection.

12.9
Sheep Ox Stag

b. Animals that live in air

The animals that live in air are called aerial animals. Different types of
birds like pigeon, parrot, crow, lophophorus, eagle, peacock, etc. are the
examples of aerial animals. The main characteristics of aerial animals are
as follows:

i. Aerial animals have boat-shaped or streamlined body which helps them
to fly easily.

ii. Their body is covered with feathers.

iii. They have wings for flying.

iv. They have air sacs in their bodies.

iv. They have light bones and toothless beak to reduce the body weight.

GREEN Science and Environment Book-6 143

v. Their beaks and claws are modified according to their feeding habit.

Fig. Fig. Fig.12.10EagleCraneParrot
Fig. Kingfisher

c. Animals that live in burrows
The animals that live in burrows are called burrowing animals. Snake, rat,

rabbit, python, mole, etc. are examples of burrowing animals. Animals
like rabbit, rat, mole, etc. make their own burrows but animals like snake,
python, etc. live in the burrows made by others The main characteristics of
burrowing animals are as follows:

i. Burrowing animals like rabbit, mole, rat, etc.
have strong nails in their digits for burrowing.
They have strong and pointed snout.
12.11

Rabbit in a burrow

ii. Burrowing animals like snake, python, etc. do
not have limbs.

12.12
Rat in a burrow

iii. Burrowing animals like snakes have strong
muscles which are adapted for crawling.

d. Animals that live on trees 12.13
Snake in a burrow

The animals that live on trees, cliffs or walls are called arboreal animals.
Monkey, lizards (garden lizard, house wall lizard), squirrel, baboon, etc.
are examples of arboreal animals. The major characteristics of arboreal
animals are as follows:

144 GREEN Science and Environment Book-6

i. Arboreal animals like monkey, baboon, Fig. Fig. Fig.
spider, monkey, etc. have long and strong
limbs adapted for climbing and jumping.
They have long fingers adapted for
climbing and holding tree branches.

12.14

ii. House wall lizards have adhesive pads on
their digits which are adapted for climbing
on walls.

12.15

iii. Spider monkeys have long and strong tail
adapted for hanging on tree branches.

iv. Arboreal animals have strong breast 12.16
muscles adapted for gliding and
climbing.

Activity 1
Observe any three aquatic animals from your locality.
Study the characteristics of these animals.
Draw a neat figure of each and label the main parts.
Write the characteristics of these animals.

Activity 2
Observe any five terrestrial animals present in your locality.
Study the characteristics of these animals.
Draw a neat figure of each and label the main parts.
Write the characteristics of each.

GREEN Science and Environment Book-6 145

Classification of plants on the basis of habitat

On the basis of habitat, plants are divided into following two groups.

1. Aquatic plants and 2. Terrestrial plants

1. Aquatic Plants

The plants that live (grow) in water are called aquatic plants. They are also
called hydrophytes. Spirogyra, hydrilla, lotus, water lily, water hyacinth,
etc. are examples of aquatic plants. They are found in river, ponds, lakes,
sea and swampy places.

Fig.

12.17 Lotus Water lily
Water hyacinth

The major characteristics of aquatic plants are as follows:

i. Aquatic plants (hydrophytes) remain covered with waxy substance which
prevents them from decaying in water.

ii. They have weak and less developed root system.

iii. They have hollow stems which helps them to float in water.

iv. Hydrophytes have weak and flexible stems.

v. Floating hydrophytes like lotus and water lily have flat and broad leaves
whereas submerged hydrophytes like hydrilla have thin and narrow
leaves.

2. Terrestrial plants

The plants that live (grow) on land are called terrestrial plants. They have
well developed root, stem and leaves. Apple, mango, rose, orange, maize,
pine, sal, sissoo, simal, etc. are examples of terrestrial plants. Different
types of plants are found in different climatic conditions. On the basis of
habitat, terrestrial plants are divided into the following four groups.

i. Plants growing in hot and moist places

ii. Plants growing in moist and shady places

iii. Plants growing in hot and dry places

iv. Plants growing in cold places

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i. Plants growing in hot and moist places

Terrestrial plants like sal, sissoo, simal, khayar, rubber, mango, coconut,
jamun, etc. grow in hot and moist places of the terai region. Their stems
are thick, long and woody. Their roots are highly developed. Their leaves
are of different shapes and sizes.

Fig. Fig.12.18 Mango tree Rubber plant Coconut plant
Sal tree

ii. Plants growing in moist and shady places

Terrestrial plants like fern, moss, marchantia, mushroom, etc. grow in
moist and shady places of the terai and hilly regions. Plants like mushroom
grow on dead and decaying organic matter. Ferns, mosses, liverworts, etc.
grow in moist, shady and cool places.

12.19 Moss Marchantia Mushroom
Fern

iii. Plants growing in hot and dry places

Terrestrial plants like Aloe vera, cactus, opuntia, Acacia, etc. grow in hot and dry
places. These plants have well developed root system adapted for absorbing
water. They have thick and fleshy stem adapted to store water. Their leaves
are reduced into thorns or spines adapted to reduce loss of water.

Fig.

12.20 Cactus Opuntia Acacia
Aloe vera

GREEN Science and Environment Book-6 147

iv. Plants growing in cold places

Terrestrial plants like cycas, dhupi, pine, deodar, spruce, cedar, etc. grow
in cold places. These plants are called coniferous plants. These plants have
thin and needle-shaped leaves. They have cones instead of true flowers.
They have well developed root, stem and leaves.

Fig.

12.21 Cycas plant Spruce plant Deodar plant
Pine tree

Activity 3

Observe any two aquatic plants from a nearby pond, lake or a river.
Study their structure carefully.

Draw neat figure of each and label the main parts.
Write down the major characteristics of each.

Activity 4
Observe any five terrestrial plants from your locality.
Study the characteristics of each plant one by one.
Draw a neat figure of each plant and label the different parts.
Write any three characteristics of each plant.

Classification of Plants (On the basis of life span)

Terrestrial plants are divided into following three groups on the basis of life
span.

1. Annual plants 2. Bienial plants 3. Perennial plants

1. Annual plants

Terrestrial plants like rice, maize, wheat, barley, millet, pea, bean, mustard,
etc. live only for one year or one season. These plants are called annual

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plants. The plants that live for only one year or one season are called
annual plants.

Fig. Fig. Fig.12.22

Maize plants Mustard plants Wheat plants Paddy plants

Annual plants germinate, grow and produce seeds within one season. These
plants die within one year after producing seeds.

2. Biennial plants

Terrestrial plants like carrot, onion, cauliflower, cabbage, turnip, radish,
etc. grow in the first year and produce flowers and seeds in the second
year. These plants are called biennial plants. The plants that live for two
years are called biennial plants.

12.23 Radish plants Onion plants Carrot plants
Cabbage plants

3. Perennial plants

Terrestrial plants like orange, mango, apple, rose, pine, walnut, sal, lychee,
guava, lemon, etc. live for many years. These plants are called perennial
plants. These plants grow and reproduce throughout their life. These
plants sprout during spring season and produce flowers and seeds. The
plants that live for many years are called perennial plants.

12.24 Pine tree Orange tree Mango ree
Apple tree

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Activity 5

Observe any ten plants present in your surroundings.
Ask the life span of each plant to your seniors.
Classify these plants on the basis of life span and fill in the given table.

Annual plants Biennial plants Perennial plants

Monocotyledonous plants and Dicotyledonous plants

On the basis of number of cotyledons in a seed, flowering plants are divided
into following two categories.

1. Monocotyledonous plants 2. Dicotyledonous plants

1. Monocotyledonous plants

The plants having only one cotyledon in their seeds are called
monocotyledonous plants. Rice, maize, wheat, sugarcane, grass, onion,
barley, millet, bamboo, etc. are examples of monocotyledonous plants. The
characteristics of monocotyledonous plants are as follows:

i. They have only one cotyledon in their seeds.

ii. They have fibrous root system.

iii. They have elongated leaves having parallel venation.

Fig.

12.25 Fibrous roots Leaves of bamboo
Monocot seed

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