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Science Edukids

Solved Exercises

ContentsUnits

1.Unit 1Food

3Food

2.Unit 2MaterialsAround us

10Solids, Liquids and Gases

Unit 3The Worldof Living

3. 14Systems of Human Body

4. 19Animals and heir BabiesT

5. 26Plants, ur Best FriendsO

6. 33Adaptation in Plants

7. 41Flowers and Insects

Unit 4Measurement,Force andEnergy

8. 52Work, Force and Energy

9. 60Electricity

10.Unit 5The Universe

64Stars and Constellations

Unit 6Natural Resources

11. 68Water

12. 74Sources of Energy

Exercise A. Circle the correct answer to each sentence below.

Energy giving food is rich in:

Calcium and iron are examples of:

Which of the following food contains fat?

3

vitamins proteins carbohydrates and fats

minerals vitamins proteins

vegetables oil almond

FoodChapter 1

This fibre is present in some food:

Amount of food is shown by:

Overcooking destroys the nutrients present in the boiling process:

minerals roughage vitamins

quantity quality food pyramid

food fruit vegetables

Proteins butter and ghee

Fat rice and potato

Vitamin A milk

Calcium egg and cheese

Carbohydrates carrots

B. Match the columns.

4

C. Answer the following questions.

What are nutrients? What is the importance of the nutrients forour body?

What is the classification of nutrients?

Why should we cook food? List four things to be kept in mind whilecooking.

How is roughage useful to the body?

Why do we need to eat enough protein food?

What is a balanced diet?

The substances which our body needs, which offer energy and help in growth are called nutrients. Nutrients provide nourishment to the body. They help to: 1. Repair our body. 2. Give energy to do our work. 3. Project us from falling sick often.

Food contains nutrients like carbohydrates, proteins, fats, vitamins and minerals. Food also contains roughage and water which is the basic need of life.

Cooking makes food soft, tasty and easily digestible. It also kills the germs in the food. Things to Remember While Cooking1. Wash the vegetables and fruits before cutting them. If they are washed after cutting, many minerals and vitamins in them may be lost.2. Do not throw away the water in which pulses and vegetables are soaked or boiled. This water contains vitamins and minerals. 3. Take just enough water to cook food. 4. Do not overcook the food. Overcooking destroys the nutrients in the food.

Roughage is the fiber present in the food. Fibre is not a nutrients but it helps our body to remove waste materials. SO roughage is very important part to our body.

Proteins help us to grow. Young children need more protein rich food. Proteins also help to repair wounds of our body.

A diet that contains all nutrients in the right amount needed by out body is called balanced diet.

Oil ghee apple juice butter cream

Lemon orange curd tomato banana

Rice sugar potato fish bread

Milk curd kheer rice cheese

Dal beans egg butter chicken

E. Tick ( ) in the correct column for each food item given below. ü

D. In the following group of food items, one food item does not belong

to the rest of the group. Underline the one that is different from the

others. Write the group to which these foods belong.

Food Protein Mineral

Rice

Chapatti

Meat

Dal

Curd

Almond

Kheer

Salad

Water

Roughage

5

VitaminFatCarbohydrate

Write down any four methods of food preservation.

Four methods of food preservation are: 1. Pickling (Mango, lime) 2. Refrigerating3. Canning (jams, jellies, butter, fish) 4. Deep freezing

Fats

Vitamins

Carbohydrates

Minerals

Proteins

ü

ü

ü

ü

üü

ü

ü

A. Circle the correct answer to each sentence below.

The scientific word for all types of materials is:

A substance which has fixed shape and volume is:

matter

ink

solid

stone

solution

air

6

Solids, Liquids and GasesChapter 3

Exercise

The substance soluble in water is:

Neither definite shape nor definite volume:

In the mixture of salt and water, salt is the:

sand

solid

solvent

salt

liquid

solute

rice

gas

solution

B. Tick ( ) the true sentence and cross (X) the wrong one.üThe particles of solids are held very closely. ü

Water changes into water vapours on freezing.

Air is a gas.

Solids take the shape of the container in which they are kept. ü

Wax is soluble in water.

All three states of matter are interchangeable. üC. Answer the following questions.

What is matter? Name the states of matter.

Define solute, solvent and solution.

Matter is anything that has mass and occupies space. Matter is found

in states: solids, liquids and gases.

The solids substances that dissolve in liquids are called solute. The

liquids in which the solute dissolves is called solvent. The mixture of

solute and solvent forms a solution.

D. How solids, liquids and gases are different from each other? Write their properties in the given space.

Solids Liquids Gases

7

Write any three properties of gases.

How molecules of solids and liquids are different from each other?

Name three soluble and insoluble substances by taking water assolvent.

1. Gases have no fixed shape.

2. Gases have no fixed volume.

3. Gases fill all the space container.

Molecules of solids are lightly parked while molecules in liquids are

not very closely parked.

Three soluble substances are Salt, Sugar, Ink. Three molecules

substances are Sand, Flour, Honey.

Hard

Cannot flow

cannot dissolve

no fixed shape

can flow

can dissolve

no fixed shape

can flow

can dissolve

Chapter 3

Exercise

Systems of Human Body

A. Fill in the blanks.

The ____________ carries messages between nerves and brain.

Blood is a thick red____________.

The process of inhaling oxygen and exhaling carbon dioxide

is called ____________.

Food passes through food canal and goes into ____________.

The urine is excreted out through ____________.

spinal cord

fluid

respiration

stomach

urethra

B. Tick ( ) the true sentence and cross (X) the wrong one.ü


How many systems a human body has? Name them.

What are the important parts of a skeletal system?

Write their functions.

What do you know about the types of muscles?

What is blood circulation?

What are nerves and what are their functions?

D. Circle the correct answer to each sentence below.

Brain is the main control center of:

nervous system skeletal system respiratory system

____________ protects the lungs, stomach and other organs.

Skull Muscles Rib-cage 8

We breathe through windpipe.

Digestion of food begins in the mouth. üKidneys filter the blood and form urine. ü

Cardiac muscles move intentionally.

Backbone has flexibility which helps to move.

A human body has eight important systems: skeletal system,

respiratory system, nervous system, excretory system, muscular

system and reproductive system.

Three important parts of a skeletal system are skull, backbone and

ribs. Skull protects the brain, the eyes, and the middle and inner ear.

Rib cage protects lungs, stomach and other organs. Backbone helps

to move. It has flexibility which helps in bending.

The muscles are of three types: skeletal, cardiac and smooth.

Blood is a thick red fluid. It goes round and round inside the body

through blood vessels. This is called circulation of blood.

Nerves are bundles of fibers which are capable of carrying messages

from organs to brain and spinal cord.

E. Match the columns.

Human body

Skull protects the

Cardiac muscles

Circulatory system consists of

Digested food is absorbed

brain, the eyes, the middleear and inner ear.

heart, blood and blood vessels.

in intestine.

move automatically

eight important systems

F. Label the diagram.

Smooth muscles work:

Nerves are the bundles of:

The air passes through ____________ and enters into lungs.

automatically

veins

nose

slowly

fibres

mouth

intentionally

muscles

windpipe

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mouth

large intestine

Liver

Stomach

Small instestine


The process of producing young ones is called:

The animals that give birth to their babies are called:

Whales and dolphins reproduce through:

photosynthesis

mammals

eggs

reproduction

birds

babies

germination

reptiles

eggs and babies

10

Animals and Their Babies Chapter 4

Exercise


Fish

Cocoon

Cockroach

Whale

Birds

shell

mammal

eggs

spawn

nymph

larva

nymph

spawn

pupa

pupa

maggot

The eggs of a frog are called: 4

The larva of the housefly is called a: 5


What is reproduction?The precess of giving birth to a young one of its own kind is called

reproduction.

How do birds reproduce?

How do mammals reproduce? Give four examples of mammals.

Describe the different stages in the life cycle of a frog.

Draw, label and explain life cycle of a butterfly.

Describe the structure of an egg with the help of a diagram.

11

Mammals give birth to their babies. Some example of mammals are

cats, horses, goats and elephants.

Birds reproduce by laying eggs.

Yolk

Albumen

Shell

Structure of an egg

Tadpole with legsTadpole

Young frog

Egg mass

Adult frog

Life cycle of frog

Different stages in the life circle of a frog are

1. Egg mass

2. Tadpole

3. Tadpole with legs

4. Young frog

5. Adult frog

Life cycle of a housefly

1st stagelarva2nd stage

larva3rd stage

larva Pupa

Young adult

Matureegg laying

femaleEggs

Maggot The larva of a house fly is called maggot.

Embryo A growing baby inside the egg is called an embryo.

Larva The young that hatches from the eggs of insects is called larva.

F. Unscramble the words and arrange them to get the life cycle of a butterfly.

O C O N O C

E. Tick ( ) the true sentence and cross (X) the wrong one.ü

A L V A R

12

Moulting The shedding of the old skin or shell of an animal is called moulting.

Metamorphosis The growing of stage insects are known as metamorphosis.

Hatching Birds on the eggs to keep them warm. After some days, the baby birds crack the shells and come out.Th is called hatching.

Nymph The baby insect that comes out of an egg is called a nymph.

Pupa The larva forms a shell around its body. This stage growth is called pupa stage.

D. Define the following terms.

Animals reproduce by laying eggs only.

The process of shedding the old skin is called moulting. ü

The egg yolk is rich in starch.

The larva of a housefly is called maggot. üTadpole is a stage in the life cycle of a butterfly.

G. Fill in the blanks.

Frogs lay eggs in______________.

All living beings give__________________to their young ones.

G E S G U P A P

The larva of a housefly is called____________________.

An egg has a_______________________called the egg shell.

Cocoon

Eggs

Larva

Pupa

water

birth

nymph

protective shell


The kitchen or food factory of a plant is the:

Plants exchange the gases through the stomata on their:

This keeps a balance between all living things:

Plants store extra food as:


Leaf

Stomata

Chlorophyll

Mushrooms

T.V programmes

absorbs sunlight.

is kitchen of plant.

promote planting of trees.

are underside of a leaf.

are non-green plants.


Which substance in the leaf absorbs sunlight?

What are the things needed by green plants to make their food?

stem

leaves

nature

starch

leaf

stem

man

sugar

root

flower

animals

glucose

13

Plants, Our Best Friends Chapter 5

Exercise

From where does the leaf get energy to make food?

Sunlight is absorbed by the chlorophyll preset in the leaf.

Green leaves of the plant prepare food by using carbon dioxide,

water and sunlight.

The leaf gets energy to make food.

From where do non-green plants derive their nutrition?

They get food from dead and decayed plants and animals.

D. Write one word for the following.

The green colour in leaves:

A word that means putting together:

Define food chain. Make a food chain for the following:

snake, grain, hawk, rat.

What is the function of stomata?

A balance between plants and animals is essential. Why?

Write a complete note on photosynthesis.

How do plants use their food?

14

Some plants like cactus do not have leaves. It has green stem.

Photosynthesis takes place in its stem.

Which part of a cactus plant prepares food for it?

The sequence showing the relationship between an organism and its

feeding habits is called a food chain.

Green leaves of the plant prepare food by using carbon dioxide, water

and sunlight. Water is absorbed by the roots from the soil and is

carried by the stem to the leaves. Carbon dioxide is taken in through

the stomata. Sunlight is absorbed by the chlorophyll present in the

leaf. The plant makes its food with carbon dioxide and water in the

presence of sunlight. The process by which the leave use to all these

to make food in the form of sugar is called photosynthesis.

The food prepared by plants is in the form of simple sugar called

glucose. It is used by the plants in a number of ways:

1. It is used to get energy.

2. It is used for the growth of a plant.

On the underside of a leaf are tiny pores called stomata through

which the exchange of gases take place.

The number of plants and animals needs to be balanced. If the

number of plants increases suddenly, the carbon dioxide breathed

out by the animals may not be enough for plants, or if there is a

sudden increases in the number of animals, plants may not be able to

supply enough food and oxygen to all the animals.

Chlorophyll

Combine

The lines seen on the leaves: Veins

The gas taken in by the leaves during day: Carbon dioxide

The gas taken out by the leaves during day: Oxygen

The liquid used to test for starch: Iodine

The food stored by plants: Starch

Why does her mother say so?

What is the purpose of keeping the plants in the balcony?

E. What will happen to a plant if:

F. Amina is fond of keeping indoor plants. Her mother tells her that she

should keep the plants in the balcony at least once in a week.

It is kept in the dark for a few days?

It is not given water for a long time?

It will not produce starch.

It will dry out.

Because plants need light to grow.

Plants prepare food in sunlight.

15

G. Label the diagram with correct words.

Root

Flower

Fruit

Bud

Stem

Leaf

Bud

Leaf

Leaf

FruitStem

Roots


Pine and spruce are the plants found on:

The fastest growing plant is:

Plants of hills have seeds in:

Underwater plants breathe through:

This is an example of floating aquatic plant:

This plant has aerial roots to breath:

plains

sugarcane

cones

stomata

water hyacinth

cactus

hills

bamboo

flowers

body surface

lotus

mango

deserts

cactus

fruits

leaf

water lily

mangrove

16

H. Join the statements with the correct words.

It takes up water and mineralsalts from the soil.

It grows abovethe ground.

It is found underthe ground.

It is the most beautiful part of

the plant.

It has veins.

It has flowers and fruits.

It has green colourdue to chlorophyll. StemFlower

LeafRoot

Adaptation in Plants Chapter 6

Exercise

C. Asad has a list of aquatic plants. Help him to put them in the right columns.

Tapegrass Lotus Water lily

DuckweedWater lettucePondweed

D. Complete the chart given below.

E. Answer the following questions.

What is the difference between terrestrial and aquatic plants?

17


Pine

Cactus

Bamboo

Mangroves

Rice

Neem

desert

plains

marshy area

hilly area

giant grass

hot, wet area

Water lettuce Tepagrass water fly

Duckweed Pondweed Lotus

Plants

Terrestrial

Plains Hills Deserts Marshy Hot anddamp area

and and and and and

Peepal Pine Cactus Mangroves rubber

Mango Fur Date palm Palm Coconut

Plants that grow on land are called terrestrial plants.

The plants that grow in water are called aquatic plants.

Write three main uses of plants that belong to the grass family.

Write the features of lotus plants which are suited to grow in water.

How mangroves are able to survive in marshy areas?

F. Chart on Tree

Make a chartpaper book on your selected tree. Write its name and

describe its shape, colour of leaves, the texture of its bark and its

height. You can rub its bark and leaves on a blank paper to get their

impressions. Also mention whether it gives flowers or fruits, whether it

is evergreen or sheds its leaves and so on.

G. Plants that grow inside the house are called indoor plants. Can you name any four such plants?

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Their roots do not get oxygen from the soil. So, some of the

roots come out the soil and take oxygen from air. These roots

are called aerial roots.

They have long and hollow stems which help the leaves and

flowers to float. Their leaves are broad and flat. The stomata

exist on the upper surface of the leaves.

Money plant

Spider plant

Bamboo palm

Peace lily

How do desert plants save water?

Name any two insectivorous plants.

The leaves of desert plants are modified into spikes to reduce

water loss.

Venus flytrap and the pitcher plant the roots of grass help to

bind the soil.

Some plants of grass family are used to prepare medicines.

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H. Circle the names of trees and flowers in the given word grid.

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K

Flowers and Insects Chapter 7

Exercise


The smallest flower in the world is:

An insect has wings:

Jasmine is a flower that blooms at:

Rearing or breeding of honey bee is called:

Insect that stings very badly:

water-mealrose rafflesia

three pairstwo pairs four pairs

day and night bothday only night only

horticulturesericulture apiculture

houseflywasp moth

B. Here are some pictures of flowers. Write their names in the given box.

C. Write one example of each of the following flowers using the given clue.

Blooms only at night:

Blooms in the daytime and closes at night:

Blooms throughout the year:

Blooms during summer:

Blooms during winter:

D. Answer the following questions.

Why is the flower an important part of a plant?

What is pollination?

Write the names of at least two useful insects.

Write the names of two harmful insects.

How can we prevent ourselves from harmful insects?

20

Vinca Marigold Rose Jasmine

Jasmine

Sunflower

Marigold

Lily

Rose

The flower an important part of the plant because it changes into fruits.

It also attracts insects to help in pollination.

The process of shifting pollen grains from one place to another is

called pollination.

Honey Bee and Silkworm.

Mosquito, Housefly.

We can spray medicines to kill harmful insects. We must not allow

water to collect in puddles and empty bottles. This will prevent

mosquitoes from laying eggs in them.

F. Fill in the blanks with the name of flowers.

for medicines for perfumes

for colour making as vegetable

Uses of flowers

G. Write down the names of the four types of microbes and one disease each of them causes.

Microbes Disease

Types ofMicrobes

Flowers come in different colours and sizes.

All flowers have a pleasant smell.

H. Tick ( ) the true sentence and cross (X) the wrong one.ü

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Honey bee Silkworm Lac insect Mosquito Housefly Weevils

Rose Arnica

Marigold Kachnar

Bacteria

Viruses

Fungi

Protozoa

Typhoid

Polio

Ringworm

Malaria

E. Fill in the table.Insects

Useful Harmful

What are microbes? Name the four main types of microbes. Microbes are very small living things that cannot be seen through the

naked eye. There are four main types of microbes.

Bacteria , Viruses , Fungi , Protozoa

ü

I. Name these:

J. Label the different parts of the insect’s body.

22

The name given to the home of bees: hive

A substance collected from the flowers by bees: nectar

An insect that spreads malaria: Mosquito

An insect that can be found in the kitchen: Cockroach

The middle part of an insect’s body is:

Feelers

China rose is a flower that blooms at night.

üMoths look like butterflies.

Plague and cholera are caused by virus.

The lac insect is used for making silk.

Honey bee is a harmful insect.

Head

Wings

Abdomen

Eye

Thorax

Wing

Work, Force and Energy Chapter 9


The capacity to do work is called:

The force attracts everything towards itself:

Knife is an example of:

Energy gets from Sun is:

Tools make our work:

B. Name the following.

The energy of muscles:

The energy we get from the Sun:

The energy of flowing water:

The energy used in running electrical appliances:

The energy produced by the blowing wind:

frictionenergy force

muscular frictional gravitational

leverwedge pulley

nuclearheat solar

complexhard easy

23

Muscular energy

Solar energy

Water energy

Electrical energy

Wind energy

What is force? What are the effects of force?


A push or pull acting on an object is called force. The force has

following effects:

1. Force can move an object.

2. Force can stop moving object.

3. Force can change the direction of a moving object.

4. Force can change the shape or size of an object.

Define energy. Give three examples of its forms.

How is wind energy useful?

What is frictional force? Why is it called a ‘necessary evil’?

When is work said to be done?

How do machines help us? Write the names of five simple machines.

What is solar energy? Name two forms into which solar energy canbe changed.

The force that tries to stop a moving object over the surface of

another object is called frictional force. This force opposes the

motion of the objects. We are able to write only because of friction

between paper and pencil or pen. It causes wear and tear of the

machine parts.

Work is said to be done when an applied force moves an object

through a distance.

When it becomes difficult to do work with our hands, we use simple

tools to do the work. Such tools are called simple machines. Lever,

pulley, screw, inclined plane and wedge are simple machines.

The energy we get from the Sun is called solar energy. Solar energy

can be changed into heat energy and light energy.

Energy is the ability to do work. We are able to do work only if we

have energy. Three forms of energy are solar energy, wind energy and

water energy.

It is used to do work like grinding the grains, pumping out water from

the ground and to generate electricity.

D. Tick ( ) the true sentence and cross (X) the wrong one.üThe ability to do work is called force.

Electric bulb converts light energy into electrical energy.

The pulley is a simple machine.

The ripened fruits fall towards the Earth due to thegravitational force.

Frictional force comes into play when we write on apaper.

24

ü

ü

ü

ü

A labourer lifts the bricks to first floor.

Ali cracks a nut.

Rida pushes the wall.

A bird flies.

Ahmad pulls a toy car.

F. Encircle the names of simple machines in the given word grid.

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B

Solar energy

Muscular energy

Grooved wheel and a rope

Ability to do work

Simple tools

G. Match the column.

simple machines

energy

energy of the Sun

pushing and pulling objects

pulley

25

E. Some situations are given here.

You have to tell whether work is done here or not.

If it is done, write yes, if not, then write no.

Simple machines cannot be used to change thedirection of an object.

yes

yes

No

yes

yes

A. Match the following columns.

In a closed circuit, conductors.

Flex is usually insulators.

Metals are there is no gap.

Non-metals are negative charge.

Electron has made of copper.

B. Fill in the blanks.

The flow of electricity is called ___________.

Current flows through a ___________.

A battery has two poles : ___________ and ___________.

Current electricity is produced in ________________.

An atom has ___________ particles.

26

ElectricityChapter 9

Exercise

current

wire

positive negative

power stattions

three

C. Tick ( ) the true sentence and cross (X) the wrong one.üThe electric circuit has some components. üPower stations are of two kinds.

Neutron has positive charge.

The movement of pieces of paper is due to static current. üBattery is a source of electricity. ü

D. Answer the following questions.

Electricity which moves along a wire is called current electricity.

What do you know about current electricity?

E. Circle the correct answer to each sentence below.

In an ___________ circuit, electricity flows from the source to device

and to the source again.

___________ is the smallest particle of an element.

Proton has ___________ charge.

Current electricity is produced in:

closedopen electric

ElectronAtomProton

negative positive double

batteriespower stations houses

27

What are the components of a circuit?

Give an example of static charge.

Write a note on battery.

Describe the types of circuit in a short note.

The electricity circuit has some components. They are wire, bulb,

switch and battery.

Take a comb and rub it with a silk cloth. Take some pieces of paper.

Bring that rubbed comb near the pieces of paper. They will jump

towards the comb and cling to the comb. The movement of small

pieces of paper is due to static current in the comb.

A battery is the source of electricity. A battery has two poles: positive

pole and negative pole. Inside a battery, there are chemicals. These

chemicals produce electricity when the two poles of a battery are

connected.

There are two types of circuit: open circuit and closed circuit. When

the path of electricity flow is complete and there is no gap, we call it

a closed circuit. When the path of electricity flow has gap, we call the

circuit as open circuit.

All stars are smaller than the Sun.

We can see stars in daytime.

Constellations appear to move across the sky from East to West.

The distance of the Sun from the Earth is 150 million kilometres.

The Big Dipper is a part of the big constellation.

Stars and Constellations Chapter 10

Exercise A. Fill in the blanks.

The ___________ is also a star.

Stars have their own ___________.

Pole Star is always ___________ on its place.

The Big Dipper is a ___________.

There are two bright stars at the end of the ________________.

B. Answer the following questions.

What is Great Bear?

What is a constellation?

Write the names of some constellations.

Discuss the Big Dipper Constellation.

What is the importance of Pole Star?

28

sun

light

fixed

big dipper

big dipper bowl

Great Bear is a constellation.

A group of stars is called constellation.

Orion, Plough, Scorpion, Bear and Pegasus are some constellations.

There is a group of seven stars on the tail side of the Great Bear.

There seven stars are called Big Dipper. The Big Dipper is a smaller

constellation. It is a part of the big constellation, i.e. The Great Bear.

We can find the direction of the North with the help of Pole Star.

C. Tick ( ) the true sentence and cross (X) the wrong one.ü

üü

D. Match the following columns.

Pointers brightest star of Little Dipper.

Pole Star is the last all the time.

Orion, Scorpion and Plough fixed on its place.

Stars shine are two bright stars.

Pole Star is always are some constellations.

E. Circle the correct answer to each sentence below.

The distance of the Sun from the Earth in million kilometers is:

On the sky at night, we can see many groups of:

Constellations have fixed:

Pole Star is located almost directly above the:

Stars have their own:

29

150

stars

style

North Pole

rock

350

rocks

position

East Pole

sky

250

planets

shape

West Pole

light


The process of changing of water vapours into liquid is known as:

Water is purified by:

Hail is found when raindrops pass through the following region:

A substance added to water to kill germs:

Water is used for:

What is evaporation?

What are the factors affecting the evaporation? Give an exampleof evaporation.

On keeping the same quantity of water in a bowl and a cup for twohours in the Sun, it has been observed that the water in the bowl wasless than in the cup. Why?

B. Answer the following questions.

condensation evaporation decantation

chlorination cooling sedimentation

very hot windy very cold

chlorine solute salt

transport drinking both

30

WaterChapter 11

Exercise

On heating, liquid water changes to water vapours. This process is

called evaporation.

Factor Effecting Evaporation of water occurs at a faster rate in the

following circumstances:

1. Temperature of the surroundings is high.

2. There is a strong wind.

3. The exposed surface of water is more.

4. The air is dry.

Example: Boiling us an example of evaporation.

Exposed surface area of the bowl is larger as compared to the cup.

Therefore, evaporation is faster in the bowl than in the cup.

C. Unjumble the given words related to the purification of water.

L I F A R I T O N T

C D E A T N A T N O I

I O L B I G N

L C O I R T N I A N O H

D S I M E A N T I T E O N

D. Correct the mistakes in the given sentences and rewrite them in your notebook.

The process in which water vapours change into water is called

evaporation.

The evaporation is slow when the exposed surface area is large.

31

Describe the process of sedimentation and decantation.

Write any three ways to purify water.

How is condensation different from evaporation?

What is chlorination?

Leave the water undisturbed for some time. The insoluble impurities

will be settled at the bottom of the water leaving it clear. This is called

sedimentation.

Chlorination: Chemicals like chlorine and potassium permanganate

are used to kill the germs and make water fit for drinking. The process

adding chlorine is called chlorination.

1. Boiling 2. Filtration 3. Chlorine

Chlorination: Chemicals like chlorine and potassium permanganate

are used to kill the germs and make water fit for drinking. The process

adding chlorine is called chlorination.

Condensations is opposites it evaporation. In condensation water

changes into solid form and in evaporation water changes into

gaseous form i.e vapours.

Filtration

Decantation

Boiling

Chlorination

Sedimentation

The process in which liquid water changes into water vapours is

called evaporation.

The evaporation is fast when the exposed surface area is large.

32

Fog is caused by tiny white flakes falling from the sky.

Filtration is the only method to purify water.

The water from rivers and wells is fit for drinking.

E. Fill in the blanks.

The dew drops freeze to form tiny________________.

The dew drops freeze to form tiny ice________________.

_____________kills the germs present in the water.

_____________ powder also kills germs in water.

The process of adding chlorine is called__________________.

Water which is clean and fit for drinking is called_____________water.

Snow is caused by tiny white takes following from the sky.

There are five methods to purify water

The water from rivers and wells is not fit for drinking.

ice crystals

crystals

Boiling

Bleaching

Chlorination

potable

Sources of Energy Sources of Energy Chapter 12


Non-renewable source of energy:

An example of a renewable source:

Fuel for household purpose:

Help us to reduce waste:

Sun coal water

Sun petroleum coal

coal petrol natural gas

Buy only necessary things, not because friends have them

Buying disposable glasses for our parties

Using our own cloth bags while shopping

two-groups three-groups four-groups

The sources of energy can be divided into:


What are renewable and non-renewable sources of energy?

What is wind energy used for now-a-days?

What is tidal energy?

How can biomass be used as a source of energy?

Write any two ways to minimize the use of energy.

What do you mean by reusing and recycling of waste?

B. Complete the given figure.

Non-renewable sources of energy

Renewable sources of energy

33

Coal Petroleum Natural gas Sun Wind Water

The sources of energy which cannot be used again and again are

called non-renewable sources of energy. These are the sources of

energy which can be used again and again.

Windmills are used in ‘wind farms’ to generate electricity.

The energy of water produced during the formation of tides is called

tidal energy.

Biomass is a waste organic matter which includes cattle dung, plants,

animals waste and sewage. This biomass is kept in a pit in the absence

of air. Due to the action of micro-organisms, it changes into gas called

biogas. This biogas is used for cooking and lighting purposes.

1. Switch off lights and fans when they are not in use.

2. Walk or use public transport whenever possible.

Using the products again which have been used once, is called reuse.

Recycling means, changing a used product into raw material and

making a new product out of this again.

Wind is harnessed using windmills.

Water is renewable source of energy.

Switch on lights and fans when not in use.

F. Fill in the blanks.

_______________is used as fuel for household purposes.

Petroleum is fossil________________.

CNG stands for________________________.

Plants make food by_______________.

_____________means, changing a used product into raw material.

G. Match the columns.

Coal, petroleum, natural gas

Major source of energy

To generate electricity

Sun, wind, water

CNG

Sun

Compressed Natural Gas

Non-renewable sources of energy

Coal

Renewable sources of energy 34

E. Tick ( ) the true sentences and cross (X) the wrong ones.üThe things like paper, glass and metals can be recycled.

Do not donate your old toys or books to the poor children.

Sun is the major source of energy.

Coal is used as gas.

D. Here is a list of some materials. Encircle the materials that can be recycled. plastic bottle, cloth, thermocol, glassware, newspaper, plastic toy, polythene, copper, iron, china ware

ü

ü

ü

ü

Natural gas

fuel

compressed natural gas

photosynthesis

Recycling

ü

H. Write the uses of the following.

Solar cooker

Solar water heater

Solar cells

Solar furnaces

To prepare food

To heat water

To generate electricity

To melt the metals or other things

solved exercises - javed publishers

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