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INDIAN SCHOOL AL WADI AL KABIR

SCIENCE REVISION WORKSHEET

CLASS VIII

1.METALS AND NON-METALS

1. Phosphorus can be stored in water but sodium can be stored only in

kerosene. Justify.

2. Give word equations to show the reactions take place in:

a) Burning of magnesium powder.

b). Iron nail in copper sulphate solution.

c). Complete combustion of carbon.

3. What is an alloy? Write the name and composition of an alloy which is used for making

aircraft bodies.

4. An element A when burnt in air forms its oxide called B. The oxide B dissolves in water to

form a base.

a. What happens when oxide B is treated with red and blue litmus?

b. What happens when Hydrochloric acid is poured on aluminum plate?

Write the chemical equation.

c. Compare the reactivity’s of sodium and gold metals towards water.

5. On the basis of the diagram given, answer the following questions:

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a. All the three testtubes, numbered I, II and III, contain a blue coloured solution of

copper sulphate and the metal as shown. Identify the test tubes in which the blue

colour would fade out after sometime.

b. Give reason for the change in colour and also mention the type of reaction.

c. Write the word equation for the following reactions:

i. Magnesium reacts with steam.

ii. Sodium reacts with water.

6. Give reasons:

a. Copper is used for making electrical cables.

b. Silver foil is used for decorating foodstuff.

c. Pickles should not be stored in metal containers.

c. Saucepan handles are made up of plastic.

7. What are the conditions necessary for rusting of iron? State any two ways to prevent

rusting of iron.

8. Distinguish between malleability and ductility.

9. (a) What do you understand by the term ‘metal reactivity series’?

(b) What inferences can you draw from the reactivity series?

(c) Arrange the following in descending order as per their reactivity towards water: iron,

sodium, magnesium and zinc.

10. An element burns in air to form an oxide. The aqueous solution of this oxide turns blue

litmus paper red. State whether the element is a metal or a non-metal. Name one such element.

11.How are alloys advantageous as compared to pure metals?

12. When a copper object is exposed to moist air for a long time, then a greenish deposit is

formed on its surface.

a. Which chemical forms the green coating?

b. State whether the green coating is acidic or basic.

13. Name a non-metal used for vulcanization of rubber.

14. Compare any three physical and chemical properties of metals and non-metals.

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2.FORCE AND FRICTION

1... Name and explain any two kinds of non-contact forces.

2...State the reason for the following:

a. The shape of a boat is somewhat similar to that of a fish.

b. Ball bearings are used in most of the machines.

c. Gymnasts often apply chalk powder on their hands.

3. a. State the effect of force that is associated with the following activities:

i. A potter making pots.

ii. A goalkeeper saving a goal, by kicking the ball away.

iii. A batsman hitting a cricket ball for a 'sixer'.

iv. A player taking a catch.

4. A box is first pulled along the surface of a table. It is then moved by putting it on a collection

of pencils. In which case would it be easierto move the box and why?

5. A car is moving towards north, what will be the direction of force of friction acting on this car

due to the surface of road?

6. Two forces 200N and 300N acting on a body in same direction. What is resultant force?

7.In tug of war, Side A applies 15N force and side B applies 88N force. Which side will the rope

move? What will be the net force acting on the rope?

8.Kabaddi players should rub their hand with soil before they start playing. Why?

9. Define lubricants.

10. State any four harmful effects of friction.

11. An object has a mass of 6 kg. What is its weight on the earth?

12. What do you understand by the term streamlining? Name a few objects which use

streamlining to reduce friction.

13. In a tug of war, three boys of team A pull the rope with forces of 100 N, 130 N and 170N. In team B,

the three members pull the rope with forces of 120 N, 140 N and 155 N. Who will win the tug of war?

What is the resultant force?

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POLLUTION OF AIR AND WATER

1. a. Name the gas produced due to incomplete combustion of fuels in cars.

b. What is smog? How is it formed?

c. Name the compound that causes damage to the ozone layer.

d. Mention the function of ozone layer.

e. How does thermal pollution affect aquatic life?

2. Justify the following statements:

a. The beautiful Taj Mahal at Agra is slowly getting eroded.

b. The high concentration of carbon dioxide in the atmosphere affects aquatic life.

c. Fertilisers are good for plants but their excessive uses are causing water pollution.

3. a. What is potable water? Mention its properties.

b. Name two methods used to purify water at home.

c. How does the use of excessive fertilizers and pesticides affect water bodies?

4.State the causes of Air pollution.

5. a. Expand CFC and SPM.

6. Observe the picture carefully and answer the following:

a. Mention two sources of air pollution.

b. We can see thick fog-like layer in the atmosphere.

i. What is it called as?

ii. How is it formed?

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iii. Write any two effects in human health.

c. Carbon dioxide in air is essential as plants use it to make food. When does it become a

pollutant and what damage does it cause?

4. MORE ABOUT LIGHT

1. a. State the laws of reflection.

b. Draw a neat labeled diagram to prove these laws.

c. Draw a neat diagram to show refraction of light when it passes from a denser medium

to a rarer medium.

2. a. Label the parts marked as 2, 3, 7 & 8.

b. Write two differences between regular and

diffused reflection.

c. What are the characteristics of an image formed

in a plane mirror?

3.Explain the terms: a) Dispersion of light b) Spectrum.

4.The following diagram shows a defect in the eye.

a) Name the defect. b) What is the cause of this defect? c) How can this defect be

rectified?

5. Observe the given picture below and define the phenomena of light shown in it.

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b) When does it happen?

6 a) Regular and Diffused reflection

7.a) How many images are formed when two plane mirrors are:

a) parallel b) Inclined at 600

8. Name the natural phenomenon which is caused by the dispersion of sunlight in the sky.

9.Refer to the diagram given below:

a. Define reflection of light.

b. Identify the angles A and B

c.If angle A is 40˚, what could be the measure of angle B? Give reason

No vision is possible at the blind spot. Give a reason.

d. What are the common defects found in the eye and suggest methods to correct

these defects?

a. What is the power of accommodation?

A pencil

A glass of water

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5. CONSERVATION OF PLANTS AND ANIMALS

1. a. Expand -

(i) IUCN (ii) WWF

b. Name a project started by the Government of India to promote wildlife awareness

among the people and to protect the species.

c. What is red data book?State the goals of Red Data Book.

2a. How are national parks different from wildlife sanctuaries?

b. Give an example for each of the following:

(i) an extinct bird (ii) an endemic species found in India.

3. Explain the terms: a) Biodiversity b) Endemic species with two examples.

4.a. Write a difference between wildlife sanctuary and biosphere reserves.

b. Give an example for an extinct species and a vulnerable species.

c. What is Project tiger? What was the objective of this project?

5.a. Explain briefly the following term:

i. Deforestation

b.What is a Biosphere Reserve? Name any two Biosphere Reserves of India.

6.What is poaching?

7. State the importance of biodiversity.

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6. COMBUSTION, FLAME AND FUEL

1. How is calorific value of a fuel related to its efficiency?

2. If you wish to purchase an ideal fuel what characteristics will you keep in mind?

3. How are fuels classified on the basis of their sources? Give example

4 .Observe carefully the picture and answer the following questions

a) Identify the apparatus

b) How does it work?

c) Mention the disadvantage of the apparatus.

d) How does throwing sand help to put off fire?

5.Draw, label and explain the different zones of a candle flame.

6. a.Identify ‘A’ and ‘B’ in the given figure.

b. Why does the fire brigade sprays water at an accident site before starting further actions?

7. a. What is meant by calorific value of a fuel?

b. Give chemical equation to show the products formed when methane burned in sufficient

amount of oxygen

c. In a candle flame, which is the region where the flame appears blue and why?

8. Why is burning of biomass better than that of coal? Give two reasons.

9. Water is heated in a water cup as shown. The water becomes hot but the paper cup does not

burn. Explain this phenomenon.

10a. Define combustion.

b.Give the conditions under which combustion takes place.

11. Give a reason:

a. LPG is a better domestic fuel than wood.

b. Green leaves do not catch fire as easily as dry leaves.

12. a. Give the significance and the characteri

c. Identify the zone used by goldsmith to melt gold

13. Write an activity to show that air is necessary for combustion.

14. Differentiate rapid and spontaneous combustion with one example

15. Whichproperty of carbon dioxide is applied in extinguishing

16. Compare any two characteristics of zones of a candle flame.

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Give the conditions under which combustion takes place.

G is a better domestic fuel than wood.

Green leaves do not catch fire as easily as dry leaves.

. Give the significance and the characteristic colour of each zone labele

Identify the zone used by goldsmith to melt gold and silver. Give a reason.

an activity to show that air is necessary for combustion.

rapid and spontaneous combustion with one example

property of carbon dioxide is applied in extinguishing fire?

any two characteristics of zones of a candle flame.

stic colour of each zone labeled in the diagram:

and silver. Give a reason.

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7. COAL AND PETROLEUM

1. Coke is preferred over coal –Justify the statement.

2. Observe the figure given below and answer the following.

A) Identify the process and mention the principle used in the process

b) Petroleum is called as black gold .why?

c) Differentiate bitumen and bituminous.

d) Define carbonization

e) Explain the process of destructive distillation of coal.

3. a. Justify the statement

Solar energy is a better alternative to fossil fuel

b) Mention the two ways by which as a responsible citizen of this world can contribute

towards the conservation of energy resources.

4. Observe the given figure and answer the following:

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a. Define the given process.

b. State the use of the product obtained at maximum and minimum boiling points.

c. Why CNG is considered as a cleaner fuel?

d. State two main differences between lignite coal and anthracite coal.

5. Explain the process of formation of coal.

6. Write four uses of natural gas.

7. The use of fossil fuel is harmful to the environment .Explain.

8. SOUND

1. a) How is sound produced?

b.) Name the part that vibrate to produce sound in the following instruments

2. Observe the picture given below and answer the following questions

a.Expand SONAR.

b.Mention the principle on which it works

c.Write one practical application of SONAR.

d.Bats are able to locate their prey accurately .How ?

3. a) Name the parts of human ear which are responsible for the following functions .

i) collection of sound vibrations from the air.

ii) Transferring signals to the brain.

b) State the auidble range of frequency of sound for the human ear.

c) People living near railway tracks know well in advance about an approaching train .Give reason.

d) mention two ways to reduce air pollution.

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4. a. Label the parts A, B and C in the diagram of the human ear given below.

b. State the function of the parts A, B and C.

a. Name the bones present in the middle ear.

5. Observe the diagram given below:

a. When is sound of ringing bell heard at its maximum?

b. What happens when vacuum pump work for some time?

c. What do you understand from this experiment?

B

C

A

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d. Why it is that flash of lightning is seen first and thunder is heard after a few

seconds?

e. A gun shot is heard by you after 2 seconds. The speed of sound in air is 330 m/s.

how far is the gun from you?

f. What is an echo?suggest two ways to prevent echo in large auditoriums.

9.CHEMICAL EFFECTS OF ELECTRIC CURRENT

1.a)Define electrolysis .

b) What is the diffrence between anode and cathode

c) During electrolysis of water hydrogen gas is liberated at which electrode.

2.A) Identify and define the process shown below.

b) The picture shows the spoon as the cathode. Give a reason.

c) Why is this method used in coating bicycles?

3.Give the difference between;

a) Electrolytes and Non – electrolytes with one example each.

4.Kitchen appliances have plastic, bakelite or wooden handles. Why?

5. In the electrolysis of copper chloride, bubbles are seen at the anode and the cathode becomes

reddish in colour respectively. Why?

6. What is the basic difference between a conductor and an electrolyte?

7. Explain with the help of a neat circuit diagram what

happens to the solution

of copper chloride when electric current is passed

through it.

8. Observe the given activity carefully and

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answer the following questions:

b. Identify and define the phenomenon.

c. What is the colour of copper sulphate solution?

d. Which electrode gets a brown coating? Give a reason.

Why are the handle bars of a bicycle coated with chromium?

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10.SOME NATURAL PHENOMENA

1.Differentiate the sub atomic particles shown in the figure.

2. a)What is a lightening conductor ?

B) How does it work ?

3.Identify the device shown below

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a) On what principal does it work?

b) Mention an application of it.

4. a) Explain briefly how an earthquake occurs.

b) Name the scale on which the destruction on earthquake is measured.

c) List two precautions that you take during earthquake.

d) a. What does the word ‘epicenter’ and ‘focus’ means with respect to earthquakes? [5]

e) c. Write two precautions each taken during lightning and earthquakes

d) Instrument used to measure the strength of an earthquake.

5.Give two ways by which substances can be charged.

6.Thunder and Lightning take place almost at the same time, which one appears to occur first?

Give a reason.

7. Study the following figure and answer the questions that follow:

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a) Name and define the process of charging shown above.

b) Differentiate between charging by conduction and charging by induction.

a. Identify the properties of electric charges shown in the figure:

b. How does a glass rod get positively charged when rubbed with silk?

c. Draw a neat diagram to show layers of Earth and label the parts.

b. What do you understand by the term Earthquake? Name the instrument

used to measure the intensity of Earthquake.

8. The diagram shows a lightning conductor. Study the figure and

answer the following: (3)

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a. What is a lightning conductor? What does a modern lightning conductor consist of?

b. How does the lightning conductor prevent damage to the building during lightning?

Explain.

c. Suggest two measures to protect ourselves from lightning.

9. Draw a neat labelled diagram of atom and label the following parts a) proton, electron neutron

and shell

11.CROP PRODUCTION AND MANAGEMENT

1.Identify the agricultal implement given below and mention its application.

2.Ramesh is a gardner and he always removes some plants from time to time from his garden.

a)What are those plants called as? Give two example .

b)How do they form a threat to other plants or crops ?

c)Differentiate manure and fertilizers .

3.What is broadcasting? Mention one disadvantage of this method.

4. Explain how leguminous plants helps in maintaining the natural fertility of soil?

5. What is a crop?

6.How are Kharif crops different from Rabi crops? Give one example each.

7.Why is it important to keep granaries clean and dry?

8.Identify the agricultural implement and mention its one use.

9. Why is seed drill considered a better method of sowing?

10.What is symbiosis? Give an example.

11. a. Explain the two modern

b. Name two agricultural practices performed by a combine.

c. A good crop yield requires availability of right amount of water

d. Sunflower and soya bean are grown along with crop plants

12. Mention the advantages of ploughing the

13. Explain how you will select good healthy seeds for sowing.

14. What precautions should be taken in sowing the

15. Write a short note on various crop diseases with example.

16. Mention the disadvantages of using

17. Differentiate biological nitrogen fixation and atmospheric nitrogen fixation.

Prepared by

Mrs Suma Senu

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What is symbiosis? Give an example.

modern methods of irrigation.

Name two agricultural practices performed by a combine.

A good crop yield requires availability of right amount of water- Give reason

d. Sunflower and soya bean are grown along with crop plants- Give reason.

ploughing the fields.

select good healthy seeds for sowing.

precautions should be taken in sowing the seeds?

a short note on various crop diseases with example.

the disadvantages of using pesticides.

biological nitrogen fixation and atmospheric nitrogen fixation.

Give reason

Give reason.