Worksheets

A. Tick (✓) the correct option:

1. Sound can travel through:
(a) gases only
(b) solids only
(c) liquids only
(d) solids, liquids and gases

2. Voice of which of the following is likely to have minimum frequency?
(a) Baby girl
(b) Baby boy
(c) A man
(d) A woman

3. Sound waves travel fastest in:
(a) air
(b) metals
(c) vacuum
(d) liquids

4. Sounds having frequency less than 20 Hz are called:
(a) supersonic
(b) ultrasonic
(c) sonar
(d) infrasonic

5. A tuning fork of frequency 384 Hz produces a lower note than one of frequency:
(a) 256 Hz
(b) 512 Hz
(c) 288 Hz
(d) 320 Hz

B. State True or False:

1. Sound cannot travel in vacuum. …………………
2. The number of oscillations per second of a vibrating object is called its time period. ……………..
3. If the amplitude of vibration is large, sound is feeble. ………………….
4. For human ears, the audible range is 20 Hz to 20,000 Hz. ………………..
5. The lower the frequency of vibration, the higher is the pitch. ……………..
6. Unwanted or unpleasant sound is termed as music. ……………..
7. Noise pollution may cause partial hearing impairment. ………………..

C. Fill in the blanks:

1. Time taken by an object to complete one oscillation is called ……………… .
2. Loudness is determined by the ………………. of vibration.
3. The unit of frequency is …………………. .
4. Unwanted sound is called ……………….. .
5. Shrillness of a sound is determined by the ………………. of vibration.

D. Answer the following questions in short:

1. A pendulum oscillates 40 times in 4 seconds. Find its time period and frequency.
2. The sound from a mosquito is produced when it vibrates its wings at the average rate of 500 vibrations per second. What is the time period of the vibration?
3. Identify the part which vibrates to produce sound in the following instruments:
(a) Dholak
(b) Sitar
(c) Flute
4. What is the difference between noise and music? Can music become noise sometimes?
5. Explain in what way noise pollution is harmful to humans.
6. List sources of noise pollution in your surroundings.
7. Your parents are going to buy a house. They have been offered one on the roadside and another three lanes away from the roadside. Which house would you suggest your parents should buy? Explain your answer.
8. Sketch larynx and explain its function in your own words.
Answer:

9. Lightning and thunder take place in the sky at the same time and at the same distance from us. Lightning is seen earlier and thunder is heard later. Can you explain why?
10. How is sound produced and how is it transmitted and heard by us?
11. A child with a moderately severe hearing loss may have defective speech. Why?

E. Match the following:

‘A’	‘B’
1. High pitch sound	a. Frequency
2. Number of vibrations produced by a vibrating particle in one second	b. Amplitude
3. Flute	c. Time period
4. Speed of sound in air	d. Frequency of vibration
5. Sound propagation	e. Vacuum
6. Time in which vibrating particle completes one vibration	f. 1000 Hz
7. A medium through which sound cannot travel	g. 330 m/sec
8. 1 kHz	h. Vibration
9. Maximum displacement of a vibrating particle from its mean position	i. Material medium
10. To and fro motion of a vibrating body about its mean position	j. Vibration air column
11. Pitch	k. High frequency
12. Loudness	l. Amplitude

F. Prepare a list of famous Indian musicians and the instruments they play:

G. Make a list of familiar musical instruments and identify their vibrating parts. A few examples are given in the table. Complete the rest of the table:

Worksheets for Class 8 Science

A. Fill in the blanks:

1. Most liquids that conduct electricity are solutions of …………………….. , ……………… and ………………… .
2. The passage of an electric current through a solution causes ………………. effects.
3. If you pass current through copper sulphate solution, copper gets deposited on the plate connected to the ………………. terminal of the battery.
4. The process of depositing a layer of any desired metal on another material by means of electricity is called …………………. .
5. Alcohol is a ……………….. .

B. Answer the following questions in short:

1. When the free ends of a tester are dipped into a solution, the magnetic needle shows deflection. Can you explain the reason?
2. Name three liquids, which when tested in the manner shown in Fig. given may cause the magnetic needle to deflect.

3. The bulb does not glow in the set up shown in Fig. given. List the possible reasons. Explain your answer.

4. Does pure water conduct electricity? If not, what can we do to make it conducting?
5. In case of a fire, before the firemen use the water hoses, they shut off the main electrical supply for the area. Explain why they do this.
6. A child staying in a coastal region tests the drinking water and also the seawater with his tester. He finds that the compass needle deflects more in the case of seawater. Can you explain the reason?
7. Is it safe for the electrician to carry out electrical repairs outdoors during heavy downpour? Explain.
8. Paheli had heard that rainwater is as good as distilled water. So she collected some rainwater in a clean glass tumbler and tested it using a tester. To her surprise she found that the compass needle showed deflection. What could be the reasons?
9. Prepare a list of objects around you that are electroplated.
10. The process that you saw (in Activity 14.7 of textbook) is used for purification of copper. A thin plate of pure copper and a thick rod of impure copper are used as electrodes. Copper from impure rod is sought to be transferred to the thin copper plate. Which electrode should be attached to the positive terminal of the battery and why?
11. Why should you not touch electrical appliances with wet hands?
12. Water from taps and handpumps conduct electricity but distilled water does not. Why?

C. Tick (✓) the correct option:

1. A tester is used to check the conduction of electricity through two liquids, labelled A and B. It is found that the bulb of the tester glows brightly for liquid A while it glows very dimly for liquid B. You would conclude that:
(a) liquid A is a better conductor than liquid B
(b) liquid B is a better conductor than liquid A
(c) both liquids are equally conducting
(d) conducting properties of liquid cannot be compared in this manner

2. Which of the following is preferred to make an electromagnet?
(a) Soft iron
(b) Steel
(c) Stainless steel
(d) Plastic

3. Current is the flow of:
(a) electrons
(b) protons
(c) neutrons
(d) charge

4. A positively charge ion is called:
(a) atom
(b) neutral ion
(c) anion
(d) cation

D. State True or False:

1. Pure water is a good conductor of electricity. ………………
2. Distilled water is an insulator. ………………
3. Leather is a good conductor of electricity. ………………
4. Petrol is a good conductor of electricity. …………..

E. Match the following:

‘A’	‘B’
1. Kerosene is	a. conductor
2. Vinegar solution is	b. electroplating
3. Electroplating works at	c. insulator
4. Electrode at positive terminal	d. chemical effect of current
5. Used for coating a thin layer of metal	e. anode

F. Find out the health concerns associated with chronium electroplating. How are people trying to resolve them?

G. Complete the following table:

Worksheets for Class 8 Science

A. Tick (✓) the correct option:

1. Which of the following cannot be charged easily by friction?
(a) A plastic scale
(b) A copper rod
(c) An inflated balloon
(d) A woollen cloth

2. When a glass rod is rubbed with a piece of silk cloth the rod:
(a) and the cloth both acquire positive charge
(b) becomes positively charged while the cloth has a negative charge
(c) and the cloth both acquire negative charge
(d) becomes negatively charged while the cloth has a positive charge

3. The two objects rubbed against each other:
(a) will lose electrons
(b) will gain electrons
(c) one will lose and other will gain electrons
(d) none of these

4. Which of the following can be charged with static electricity?
(a) Metal
(b) Alloy
(c) Insulator
(d) Semiconductor

5. Which of the following occurs during lightning?
(a) Nitrogen fixation
(b) Acid rain
(c) Greenhouse effect
(d) None of these

B. State True or False:

1. Like charges attract each other. ……………..
2. A charged glass rod attract a charged plastic straw. ………………..
3. Lightning conductor cannot protect a building from lightning. ……………….
4. Earthquakes can be predicted in advance. ……………..

C. Answer the following questions in short:

1. Sometimes, a crackling sound is heard while taking off a sweater during winters. Explain.
2. Explain why a charged body loses its charge if we touch it with our hand.
3. Name the scale on which the destructive energy of an earthquake is measured. An earthquake measures 3 on this scale. Would it be recorded by a seismograph? Is it likely to cause much damage?
4. Suggest three measures to protect ourselves from lightning.
5. Explain why a charged balloon is repelled by another charged balloon whereas an uncharged balloon is attracted by another charged balloon.
6. Describe with the help of a diagram an instrument which can be used to detect a charged body.

7. List three states in India where earthquakes are more likely to strike.
8. Suppose you are outside your home and an earthquake strikes. What precaution would you take to protect yourself?
9. The weather department has predicted that a thunderstorm is likely to occur on a certain day. Suppose you have to go out on that day. Would you carry an umbrella? Explain.
10. Mention three precautions that you will take to protect yourself if earthquake strikes when you are inside the house.
11. Explain why it is safer to use a wireless telephone instead of a landline telephone?

D. Fill in the blanks:

1. Like charges ……………….. and unlike charges ………………. .
2. The explosive sound heard during lightning is called ……………. .
3. A negatively-charged object will ……………….. a positively charged object.
4. Charging a body by touching it with a charged body is called charging by ……………….. .

E. Match the following:

‘A’	‘B’
1. A device which is used to test whether an object is carrying charge or not is known as	a. Earthing
2. The process of transferring of charge from a charged object to the earth is called	b. Electroscope
3. A device used to protect buildings from the effect of lightning is called	c. Earthquake
4. A sudden shaking or trembling of the earth which lasts for a very short time is called	d. Lightning conductors

F. Open a water tap. Adjust the flow so that it forms a thin stream. Charge a refill. Bring it near the water stream. Observe what happens. Write a short report on the activity:

G. Collect the objects and the materials listed in table. Try to charge each by rubbing with the materials mentioned in the table. Record your findings. You can add more items to table:

Worksheets for Class 8 Science

A. Answer the following questions in short:

1. Suppose you are in a dark room. Can you see objects in the room? Can you see objects outside the room. Explain.
2. Differentiate between regular and diffused reflection. Does diffused reflection mean the failure of the laws of reflection?
3. Mention against each of the following whether regular or diffused reflection will take place when a beam of light strikes. Justify your answer in each case:
(a) Polished wooden table:
(b) Chalk powder:
(c) Cardboard surface:
(d) Marble floor with water spread over it:
(e) Mirror:
(f) Piece of paper:
4. State the laws of reflection.
5. Describe an activity to show that the incident ray, the reflected ray and the normal at the point of incidence lie in the same plane.
6. Describe the construction of a kaleidoscope.
7. Draw a labelled sketch of the human eye.

8. Gurmit wanted to perform Activity 16.8 of NCERT textbook using a laser torch. Her teacher advised her not to do so. Can you explain the basis of the teacher’s advise?
9. Explain how you can take care of your eyes.
10. What is the angle of incidence of a ray if the reflected ray is at an angle of 90° to the incident ray?
11. How many images of a candle will be formed if it is placed between two parallel plane mirrors separated by 40 cm?
12. Two mirrors meet at right angles. A ray of light is incident on one at an angle of 30° as shown in Fig. Draw the reflected ray from the second mirror.


13. Boojho stands at A just on the side of a plane mirror as shown in Fig. Can he see himself in the mirror? Also can he see the image of objects situated at P, Q and R?

14. (a) Find out the position of the image of an object situated at A in the plane mirror (see Fig.).

(b) Can Paheli at B see this image (see Fig.)?
(c) Can Boojho at C see this image (see Fig.)?
(d) When Paheli moves from B to C, where does the image of A move (see Fig.)?
15. What kind of lens is there in our eyes? Where does it form the image of an object?
16. Explain the process which enables us to perceive motion in a cartoon film.

B. Fill in the blanks:

1. A person 1 m in front of a plane mirror seems to be ……………… m away from his image.
2. If you touch your ………………… ear with right hand in front of a plane mirror it will be seen in the mirror that your right ear is touched with …………………… .
3. The size of the pupil becomes …………………. when you see in dim light.
4. Night birds have ………………….. cones than rods in their eyes.
5. A ………………….. object is a source of light.
6. The sun is a ………………… body whereas moon is a ……………………… body.

C. Tick (✓) the correct option:

1. Angle of incidence is equal to the angle of reflection.
(a) Always
(b) Sometimes
(c) Under special conditions
(d) Never

2. Image formed by a plane mirror is:
(a) virtual, behind the mirror and enlarged
(b) virtual, behind the mirror and of the same size as the object
(c) real at the surface of the mirror and enlarged
(d) real, behind the mirror and of the same size as the object

3. The ray of light which falls on a mirror is known as a/an:
(a) incident ray
(b) emergent ray
(c) reflected ray
(d) transmitted ray

4. The splitting of white light into its seven colours constituent is known as :
(a) refraction
(b) dispersion
(c) reflection
(d) deviation

5. An area at the junction of the optic nerve and the retina is:
(a) blind spot
(b) eye lens
(c) yellow spot
(d) pupil

D. State True or False:

1. The transparent and protective layer over the cornea is called conjunctiva. ………………
2. Blindness by birth is called congenital blindness. ………………..
3. Reflected ray is the ray of light that falls on a mirror. ………………
4. Light travels in a straight line. ……………..
5. During dispersion any kind of light splits into seven colours. ………………….

E. Make your own mirror. Take a glass strip on glass slab. Clean it and put it on a white sheet of paper. See yourself in the glass. Next put the glass slab on a black sheet of paper. Again look into the glass. In which case do you see yourself better and why?

F. Draw a line making an angle of 90° to the line representing the mirror at the point where the incident ray strikes the mirror. Measure the angle of incidence and the angle of reflection. Repeat the activity several times by changing the angle of incidence. Enter the data in the table given below:

Worksheets for Class 8 Science

A. Tick (✓) the correct option:

1. Which of the following is NOT a member of the solar system?
(a) An asteroid
(b) A satellite
(c) A constellation
(d) A comet

2. Which of the following is not a planet of the sun?
(a) Sirius
(b) Mercury
(c) Saturn
(d) Earth

3. Phases of the moon occur because:
(a) we can see only that part of the moon which reflects light towards us
(b) our distance from the moon keeps changing
(c) the shadow of the earth covers only a part of moon’s surface
(d) the thickness of the moon’s atmosphere is not constant

4. Farthest planet of solar system at present is:
(a) Uranus
(b) Pluto
(c) Mercury
(d) Neptune

B. Fill in the blanks:

1. The planet which is farthest from the sun is ………………. .
2. The planet,which appears reddish in colour is ……………….. .
3. A group of stars that appear to form a pattern in the sky is known as a ………………. .
4. A celestial body that revolves around a planet is known as ………………. .
5. Shooting stars are actually not ……………….. .
6. Asteroids are found between the orbits of …………………… and ………………. .

C. State True or False:

1. Pole star is a member of the solar system. ……………………
2. Mercury is the smallest planet of the solar system. ………………..
3. Uranus is the farthest planet in the solar system. ……………….
4. INSAT is an artificial satellite. ………………..
5. There are nine planets in the solar system. ……………..
6. Constellation Orion can be seen only with a telescope. ……………………

D. Match the following:

‘A’	‘B’
1. Inner planets	a. Saturn
2. Outer planets	b. Pole star
3. Constellation	c. Great Bear
4. Satellite of the earth	d. Moon
	e. Earth
	f. Orion
	g. Mars

E. Answer the following questions in short:

1. In which part of the sky can you find Venus if it is visible as an evening star?
2. Name the largest planet of the solar system.
3. What is constellation? Name any two constellations.
4. Draw sketches to show the relative positions of prominent stars in
(a) Ursa Major
(b) Orion.

5. Name two objects other than planets which are members of the solar system.
6. Explain how you can locate the Pole Star with the help of Ursa Major.
7. Do all the stars in the sky move? Explain.
8. Why is the distance between stars expressed in light years? What do you understand by the statement that a star is eight light years away from the earth?
9. The radius of Jupiter is 11 times the radius of the earth. Calculate the ratio of the volumes of Jupiter and the earth. How many earths can Jupiter accomodate?
10. Boojho made the following sketch of the solar system. Is the sketch correct? If not, correct it.

11. Can we talk on the moon?
12. Why can’t we see stars during the day?

F. Solve the following riddle and try to make similar riddles yourself:

My first is in VAN but not in PAN
My second is in Earth and also in HEAVEN
My third is in ONE and not in TWO
MY fourth is in BUN and also in FUN
MY last is in STAR but not in RADAR
I am a planet that moves round the Sun. …………………..

G. India has a vast network of its artificial satellites working for different purposes. Try to find out any two such satellites and their main purpose:

a. Name of Satellite
(1)
(2)

b. Purpose
(1)
(2)

H. Complete the table:

Worksheets for Class 8 Science

A. Answer the following questions in short:

1. What are the different ways in which water gets contaminated?
2. At an individual level, how can you help reduce air pollution?
3. Clear, transparent water is always fit for drinking. Comment.
4. You are a member of the muncipal body of your town. Make a list of measures that would help your town to ensure the supply of clean water to all its residents.
5. Explain the differences between pure air and polluted air.
6. Explain circumstances leading to acid rain. How does acid rain affect us?
7. Describe the ‘Greenhouse Effect’ in your own words.
8. Prepare a brief speech on global warming. You have to deliver the speech in your class.
9. Describe the threat to the beauty of the Taj Mahal.
10. Why does the increased level of nutrients in the water affect the survival of aquatic organisms?
11. How can we reduce, reuse and recycle water?
12. A lot of dry leaves are collected in a school garden and are burnt everyday. Do you think that it is right to do so? If not, what should be done to dispose off the dry leaves?

B. Tick (✓) the correct option:

1. Which of the following is not a greenhouse gas?
(a) Carbon dioxide
(b) Sulphur dioxide
(c) Methane
(d) Nitrogen

2. The exhaust from CNG vehicles contains too much of:
(a) SPM
(b) sulphur dioxide
(c) carbon monoxide
(d) none of these

3. Of the total water on earth, freshwater is:
(a) 97.4%
(b) 2.6%
(c) 2.0%
(d) 0.01%

4. Fertilisers and pesticides are the main cause of:
(a) water pollution
(b) soil pollution
(c) air pollution
(d) food poisoning

5. Air pollution can be prevented by:
(a) burning fuels like wood and coal
(b) deforestation
(c) using biogas and solar energy as fuels
(d) volcanic eruption

C. Fill in the blanks:

1. Algae can be used to produce oxygen by the …………………. process.
2. Suspended particles of dust, smoke and sand are called ……………….. .
3. Two examples of greenhouse gases are …………………. and …………….. .
4. …………………. or ………………… can be used to kill the disease causing microorganisms present in water.

D. State True or False:

1. There are no alternatives for fossil fuels. ………………
2. Water pollution is caused by the waste water given out by the factories. ………………..
3. Waste water from agricultural land do not cause water pollution. ……………………
4. CNG contains sulphur which forms sulphur dioxide upon burning. …………………
5. Clean fuels like natural gas do not contribute to the greenhouse gases. …………………..

E. Match the following:

‘A’	‘B’
1. Water pollution	a. CO2
2. Air pollution	b. CFCs
3. Global warming	c. Acid rain
4. Ozone layer depletion	d. Fertiliers, pesticides
5. Corrosion of statues, buildings	e. Oxides of nitrogen and sulphur

F. Find out with the help of your teachers and the internet (if possible), whether there are any international agreements to control global warming. Which are the gases covered under these agreements?

G. Write one cause and harmful effects of following pollutants:

Worksheets for Class 8 Science

A. Answer the following questions in short:

1. Explain the importance of reproduction in organisms.
2. Describe the process of fertilisation in human beings.
3. Give two differences between a zygote and a foetus.
4. Define asexual reproduction. Describe two methods of asexual reproduction in animals.
5. In which female reproductive organ does the embryo get embedded?
6. What is metamorphosis? Give examples.
7. Differentiate between internal fertilisation and external fertilisation.
8. Why do you think it is necessary for frogs and fish to lay so many eggs?
9. What do you think would have happened if humans also give birth to a large number of babies at the same time?

B. Tick (✓) the correct option:

1. Internal fertilisation occurs:
(a) in female body
(b) outside female body
(c) in male body
(d) outside male body

2. A tadpole develops into an adult frog by the process of:
(a) fertilisation
(b) metamorphosis
(c) embedding
(d) budding

3. The number of nuclei present in a zygote is:
(a) none
(b) one
(c) two
(d) four

4. Egg producing animals such as birds are called:
a) viviparous
(b) oviparous
(c) hermaphrodite
(d) unisexual

C. State True or False:

1. Oviparous animals give birth to young ones. ………………
2. Each sperm is a single cell. ………………..
3. External fertilisation takes place in frog. …………….
4. A new human individual develops from a cell called gamete. ……………
5. Egg laid after fertilisation is made up of a single cell. ………………….
6. Amoeba reproduces by budding. ……………….
7. Fertilisation is necessary even in asexual reproduction. ………………….
8. Binary fission is a method of asexual reproduction. ………………..
9. A zygote is formed as a result of fertilisation. ………………
10. An embryo is made up of a single cell. ……………….

D. Fill in the blanks:

1. The process of ………………… ensure continuity of life.
2. …………………….. are unisexual.
3. The animals that produce only one kind of gametes are known as ………………… .
4. The cells involved in the sexual reproduction are called …………….. .
5. The fusion product of sperm and ovum is known as ……………….. .

E. Visit a poultry farm. Talk to the manager of the farm and try to find out the answers to the following:

1. What are layers and broilers in a poultry farm?
2. Do hens lay unfertilised eggs?
3. How can you obtain fertilised and unfertilised eggs?
4. Are the eggs that we get in the stores fertilised or unfertilised?
5. Can you consume fertilised eggs?
6. Is there any difference in the nutritional value of fertilised and unfertilised eggs?

F. Try to name some of the young ones by completing the table:

G. Complete the crossword puzzle using the clues given below:

Across (→)
1. The process of the fusion of the gametes.
6. The type of fertilisation in hen.
7. The term used for bulges observed on the sides of the body of hydra.
8. Eggs are produced here.

Down (↓)
2. Sperms are produced in these male reproductive organs.
3. Another term for the fertilised egg.
4. These animals lay eggs.
5. A type of fission in amoeba.

Worksheets for Class 8 Science

A. State True or False:

1. Unicellular organisms have one-celled body. ………………
2. Muscle cells are branched. ………………..
3. The basic living unit of an organism is an organ. ……………….
4. Amoeba has irregular shape. ……………………
5. Most of the cells have nucleus. …………………

B. Answer the following questions in short:

1. Make a sketch of the human nerve cell. What function do nerve cells perform?

2. Write short notes on the following:
(a) Cytoplasm
(b) Nucleus of a cell
3. Which part of the cell contains organelles?
4. Make sketches of animal and plant cells. State three differences between them.

Animal Cells	Plant Cells

5. State the difference between eukaryotes and prokaryotes.
6. Where are chromosomes found in a cell? State their function.
7. ‘Cells are the basic structural units of living organisms.’ Explain.
8. Explain why chloroplasts are found only in plant cells?
9. Why do plant cells need a cell wall, and animals cells do not?
10. Do the number of cells in an organism affect its functioning? Give reasons.

C. Tick (✓) the correct option:

1. The cell wall is made of a non-living material known as:
(a) chromosome
(b) nucleic acid
(c) cellulose
(d) protoplasm

2. Food-making structures found in the cells of green plants are called:
(a) chloroplasts
(b) chromosomes
(c) mitochondria
(d) chromoplasts

3. Cells which are long and branched are:
(a) muscle cells
(b) nerve cells
(c) red blood cells
(d) ostrich egg cells

4. The largest known cell is:
(a) ostrich egg
(b) RBC
(c) WBC
(d) skin cell

D. Fill in the blanks:

1. The ……………. is the control centre of the cell.
2. An ……………. is a cell that can be seen without a microscope.
3. Energy is produced in ………………… .
4. Cell wall is found in ………………… cell.

E. Match the following:

‘A’ (Items)	‘B’ (Features)
1. Amoeba	a. WBC
2. Blood	b. Largest cell
3. Ostrich egg	c. Flagella
4. Paramecium	d. Pseudopodia
5. Bacteria	e. Smallest cell

F. Compare the plant cell and animal cell, then complete the table:

G. Complete the crossword with the help of clues given below:

Across (→)
1. This is necessary for photosynthesis.
3. Term for component present in the cytoplasm.
6. The living substance in the cell.
8. Units of inheritance present on the chromosomes.

Down (↓)
1. Green plastids.
2. Formed by collection of tissues.
4. It separates the contents of the cell from the surrounding medium.’
5. Empty structure in the cytoplasm.
7. A group of cells.

Worksheets for Class 8 Science

A. Fill in the blanks:

1. A place where animals are protected in their natural habitat is called …………… .
2. Species found only in a particular area is known as ……………. .
3. Migratory birds fly to far away places because of …………………. changes.
4. Corbett National Park is located in ………………… .
5. Conservation means ………………… environment.

B. Answer the following questions in short:

1. Differentiate between the following:
(a) Wildlife sanctuary and biosphere reserve.
Answer:

(b) Zoo and wildlife sanctuary.
Answer:

(c) Endangered and extinct species.
Answer:

(d) Flora and fauna.
Answer:

2. Discuss the effects of deforestation on the following:
(a) Wild animals
(b) Environment
(c) Villages (Rural areas)
(d) Cities (Urban areas)
(e) Earth
(f) The next generation
3. What will happen if:
(a) we go on cutting trees?
(b) the habitat of an animal is disturbed?
(c) the top layer of soil is exposed?
4. Answer in brief:
(a) Why should we conserve biodiversity?
(b) Protected forests are also not completely safe for wild animals. Why?
(c) Some tribals depend on the jungle. How?
(d) What are the causes and consequences of deforestation?
(e) What is Red Data Book?
(f) What do you understand by the term migration?
5. In order to meet the ever-increasing demand in factories and for shelter, trees are being continually cut. Is it justified to cut trees for such projects? Discuss and prepare a brief report.
6. How can you contribute to the maintenance of green wealth of your locality? Make a list of actions to be taken by you.
7. Explain how deforestation leads to reduced rainfall.
8. Find out about national parks in your state. Identify and show their location on the outline map of India.

9. Why should paper be saved? Prepare a list of ways by which you can save paper.
10. Reforestation can take place naturally. Why?
11. What would happen if we had no wood?

C. Tick (✓) the correct option:

1. …………………. are responsible for extinction of a species.
(a) Loss of habitat
(b) Excessive use of chemical fertilizers and pesticides
(c) Providing habitats for animals in zoo
(d) Clearing of land to plant crops and build road

2. Which one of the following is not under a conservation category of wildlife?
(a) Extinct
(b) Endangered
(c) Endemic
(d) Vulnerable

3. Different species are classified into different threat categories in the:
(a) yellow data book
(b) black data book
(c) blue data book
(d) red data book

4. WWF works in the field of:
(a) wildlife conservation
(b) water conservation
(c) forest conservation
(d) human resource conservation

D. State True or False:

1. Naturally occuring useful materials are called natural resources. …………….
2. Population growth has no effect on depletion of natural resources. ……………
3. Zoo and sanctuaries keep orphaned or sick animal. ………………….
4. Species of plants together are known as flora whereas those of animals are known as fauna. ………….
5. Endemic species are species found in a particular area only. ………………

E. Match the following:

‘A’	‘B’
1. The plants and animals found in a particular area are termed.	a. Species
2. A group of population which are capable of interbreeding	b. Flora and fauna
3. Provide protection and suitable living conditions to wild animals	c. Endangered animals
4. Animals whose numbers are diminishing are known as the	d. Wildlife sanctuaries to a level that they might face extinction

F. Make a list of various uses of papers. Observe currency notes carefully. Do you find any difference between a currency paper and paper of your notebook? Find out where currency paper is made.

G. Complete the word puzzle:

Across (→)
1. Species which have vanished.
3. Species found only in a particular habitat.
4. Variety of plants, animals and microorganisms found in an area.

Down (↓)
1. Species on the verge of extinctiort.
2. A book carrying information about endangered species.
5. Consequence of deforestation.

Worksheets for Class 8 Science

A. Answer the following questions in short:

1. List conditions under which combustion can take place.
2. Explain how the use of CNG in automobiles has reduced pollution in our cities.
3. Compare LPG and wood as fuels.
4. Give reasons:
(a) Water is not used to control fires involving electrical equipment.
(b) LPG is a better domestic fuel than wood.
(c) Paper by itself catches fire easily whereas a piece of paper wrapped around an aluminium pipe does not.
5. Make a labelled diagram of a candle flame.

6. Name the unit in which the calorific value of a fuel is expressed.
7. Explain how CO₂ is able to control fires.
8. It is difficult to burn a heap of green leaves but dry leaves catch fire easily. Explain.
9. Which zone of a flame does a goldsmith use for melting gold and silver and why?
10. In an experiment 4.5 kg of a fuel was completely burnt. The heat produced was measured to be 180,000 kJ. Calculate the calorific value of the fuel.
11. Can the process of rusting be called combustion? Discuss.
12. Abida and Ramesh were doing an experiment in which water was to be heated in a beaker. Abida kept the beaker near the wick in the yellow part of the candle flame. Ramesh kept the beaker in the outermost part of the flame. Whose water will get heated in shorter time?
13. You are provided with three watch glasses containing milk, petrol and mustard oil, respectively. Suppose you bring a burning candle near these materials one by one which material(s) will catch fire instantly and why?
14. People usually keep Angeethi/burning coal in their closed rooms during winter season. Why is it advised to keep the door open?

B. Fill in the blanks:

1. Burning of wood and coal causes ………………. of air.
2. A liquid fuel, used in homes is …………… .
3. Fuel must be heated to its ……………….. before it starts burning.
4. Fire produced by oil cannot be controlled by ………………… .

C. Tick (✓) the correct option:

1. Good fuels have:
(a) low ignition temperature and high calorific value
(b) low ignition temperature and low calorific value
(c) high ignition temperature and high calorific value
(d) high ignition temperature and low calorific value

2. Calorific value of a fuel is the heat energy produced when:
(a) any amount of the fuel is completely burnt
(b) one kilogram of the fuel is completely burnt
(c) one milligram of the fuel is completely burnt
(d) hundred grams of the fuel is completely burnt

3. Acid rain can be caused by the burning of:
(a) petrol
(b) CNG
(c) diesel
(d) coal

4. Which of these is a solid pollutant?
(a) SPM
(b) Carbon monoxide
(c) Nitrogen oxides
(d) Sulphur dioxide

D. State True or False:

1. Air is necessary for combustion. ………………
2. The fuel in candle is its wick that bums to produce heat and light. ………………..
3. Soot produced by combustion is not harmful for us as it consists of oily carbon. ……………..
4. Oxygen is very effective in putting out fire. ………………….

E. Match the following:

‘A’	‘B’
1. Fossil fuel	a. Combustible substance
2. Combustion	b. Carbon dioxide
3. Petrol	c. Petroleum
4. Gobar gas	d. Burning of fuels
5. Fire extinguisher	e. Cow dung

F. Find out the number, type and location of fire extinguishers available in your school, nearby shops and factories. Write a brief report about the preparedness of these establishments to fight fire.

G. Talk to people who use LPG at home. Find out what precautions they take in LPG.

H. Record your observation and mention whether on burning the material forms a flame or not:

I. Make a list of fuels familiar to you. Group them as solid, liquid and gaseous fuels as in the table given below:

Worksheets for Class 8 Science