Class 8 back exercise

 Chapter 1 "Crop production and management"

Question 1.
Select the correct word from the following list and fill in the blanks.
float, water, crop, nutrients, preparation
(a) The same kind of plants grown and cultivated on a large scale at a place is called _____

(b) The first step before growing crops is _______ of the soil.
(c) Damaged seeds would ______ on top of the water.
(d) For growing a crop, sufficient sunlight and ______ and ______ from the soil are essential.

Answer:
(a) crop
(b) preparation
(c) float
(d) water, nutrients

Question 2.
Match items in column A with those in column B.

(1) Kharif crop---> Paddy , maize

(2) Rabi crops-----> Wheat, gram, pea

(3) chemical fertilizers---> urea and super phosphate

(4) organic manure ----> Animal excreta, cow dung , urine and plant waste.

Question 3.
Give two examples of each.
(a) Kharif crop
(b) Rabi crop
Answer:
(a) Kharif crop: Paddy and maize
(b) Rabi crop: Wheat and gram

Question 10.
Arrange the following boxes in the proper order to make a flow chart of sugarcane crop production

Answer:-

Chapter 2

Question 1.
Fill in the blanks.
(a) Microorganisms can be seen with the help of a _____
(b) Blue-green algae fix ______ directly from the air to enhance the fertility of soil.
(c) Alcohol is produced with the help of _____
(d) Cholera is caused by ______
Answer:
(a) microscope
(b) nitrogen
(c) yeast
(d) bacteria

Question 2.
Tick the correct answer.
(a) Yeast is used in the production of
(i) sugar
(ii) alcohol
(iii) hydrochloric acid
(iv) oxygen
Answer:
(ii) alcohol

(b) The following is an antibiotic:
(i) sodium bicarbonate
(ii) streptomycin
(iii) alcohol
(iv) yeast
Answer:
(ii) streptomycin

(c) Carrier of malaria-causing protozoan is:
(i) female Anopheles mosquito
(ii) cockroach
(iii) housefly
(iv) butterfly
Answer:
(i) female Anopheles mosquito

d) The most common carrier of communicable diseases is
(i) ant
(ii) housefly
(iii) dragonfly
(iv) spider
Answer:
(ii) housefly

e) The bread or idli dough rises because of:
(i) heat
(ii) grinding
(iii) growth of yeast cells
(iv) kneading
Answer:
(iii) growth of yeast cells

f) The process of conversion of sugar into alcohol is called
(i) nitrogen fixation
(ii) moulding
(iii) fermentation
(iv) infection
Answer:
(iii) fermentation

Question 3.
Match the organisms in column A with their action in column B.

i.) Bacteria ---> Causing cholera

ii) Rhizobium ---> Fixing nitrogen

iii) Lactobacillus---> setting of curd

iv) yeast---> Baking of bread

v) A protozoan ---> causing malaria

vi) A virus ---> causing AIDS

Chapter 3 Synthetic fibres and plastics

Question 2.
Mark (✓) the correct answer.
Rayon is different from synthetic fibres because
(a) it has a silk-like appearance.
(b) it is obtained from wood pulp.
(c) its fibres can also be woven like those of natural fibres.
Answer:
(b) it is obtained from wood pulp.

Question 3.
Fill in the blanks with appropriate words.
(a) Synthetic fibres are also called ____ or ____ fibres.
(b) Synthetic fibres are synthesised from a raw material called _____
(c) Like synthetic fibres, plastic is also a _____
Answer:
(a) man-made, artificial fibres
(b) petrochemicals
(c) polymer

Question 13.

Match, the terms of column A correctly with the phrases given in column B.

(i) Polyester-->Fabrics do not wrinkle easily

(ii) Teflon-->Used to make non-stick cookware

(iii) Rayon-->Prepared by using wood pulp

(iv) Nylon-->Used for making parachutes and stockings

Chapter 4 

question 1.

Which of the following can be beaten into thin sheets?
(a) Zinc
(b) Phosphorus
(c) Sulphur
(d) Oxygen
Answer:
(a) Zinc

Question 2.
Which of the following statements is correct?
(a) All metals are ductile.
(b) All non-metals are ductile.
(c) Generally, metals are ductile.
(d) Some non-metals are ductile.
Answer:
(c) Generally, metals are ductile

Question 3.
Fill in the blanks.
(a) Phosphorus is a very ____ non-metal.
(b) Metals are _____ conductors of heat and _____
(c) Iron is ______ reactive than copper.
(d) Metals react with acids to produce ______ gas.
Answer:
(a) reactive
(b) good, electricity
(c) more
(d) hydrogen

Question 4.
Mark ‘T’ if the statement is true and ‘F’ if it is false.
(a) Generally, non-metals react with acids.
(b) Sodium is a very reactive metal.
(c) Copper displaces zinc from zinc sulphate solution.
(d) Coal can be drawn into wires.
Answer:
(a) False
(b) True
(c) False
(d) False

Question 8.
Match the substances given in column A with their uses given in column B.

(i)Gold--->Jewellery
(ii)Iron-->Machinery
(iii)Aluminium--->Wrapping food
(iv)Carbon--->Fuel
(v) Copper--->Electric wire
(vi) Mercury--->Thermometers

Chapter 5 "Coal and petroleum"

Question 2.

Name the petroleum product used for surfacing of roads.

Answer:

Bitumen

Question 4.

Fill in the blanks.

(a) Fossils fuels are ____ , ____ and ____

(b) Process of separation of different constituents from petroleum is called ______

(c) Least polluting fuel for vehicle is ______

Answer:

(a) coal, petroleum, natural gas

(b) refining

(c) CNG

Question 5.

Tick True/False against the following statements.

(a) Fossil fuels can be made in the laboratory.

(b) CNG is more polluting fuel than petrol.

(c) Coke is an almost pure form of carbon.

(d) Coal tar is a mixture of various substances.

(e) Kerosene is not a fossil fuel.

Answer:

(a) False ,(b) False ,(c) True , (d) True, (e) False

Chapter 6 " Combustion and flame"

Question 2.
Fill in the blanks.
(a) Burning of wood and coal causes _____ of air.
(b) A liquid fuel, used in homes is ______
(c) Fuel must be heated to its ______ before it starts burning.
(d) Fire produced by oil cannot be controlled by ______
Answer:
(a) pollution
(b) LPG
(c) ignition temperature
(d) water

Chapter 7" Conservation of plants and animals"

Question 1.
Fill in the blanks.
(a) A place where animals are protected in their natural habitat is called ______
(b) Species found only in a particular area is known as 
(c) Migratory birds fly to faraway places because of ________ changes.
Answer:
(a) Wildlife sanctuary
(b) endemic species
(c) climatic

Chapter 8 

Question 1.
Indicate whether the following statements are True (T) or False (F).
(a) Unicellular organisms have a one-celled body.
(b) Muscle cells are branched.
(c) The basic living unit of an organism is an organ.
(d) Amoeba has an irregular shape.
Answer:
(a) True
(b) True
(c) False
(d) True

Chapter 9"Reproduction in animals"

3.Choose the most appropriate answer.

(a) Internal fertilisation occurs

(i) in female body.

(ii) outside female body.

(iii) in male body.

(iv) outside male body.

(b) A tadpole develops into an adult frog by the process of:

(i) fertilisation

(ii) metamorphosis

(iii) embedding

(iv) budding

(c) The number of nuclei present in a zygote is:

(i) none

(ii) one

(iii) two

(iv) four

Answer:

(a) (i); (b) (ii); (c) (ii)

Question 4.

Indicate whether the following statements are True (T) or False (F).

Oviparous animals give birth to young ones.

Each sperm is a single cell.

External fertilisation takes place in frog.

A new human individual develops from a cell called gamete.

Egg laid after fertilisation is made up of a single cell.

Amoeba reproduces by budding.

Fertilisation is necessary even in asexual reproduction.

Binary fission is a method of asexual reproduction.

A zygote is formed as a result of fertilisation.

An embryo is made up of a single cell.

Answer:

False, True ,True, False ,True ,False, False , True , True , False

Chap 10

Question 1.
What is the term used for secretions of endocrine glands responsible for changes taking place in the body?
Answer:
Hormones

Question 7.
Choose the correct option.
(a) Adolescents should be careful about what they eat, because:
(i) proper diet develops their brains.
(ii) proper diet is needed for the rapid growth taking place in their body.
(iii) adolescents feel hungry all the time.
(iv) taste buds are well developed in teenagers

(b) Reproductive age in women starts when their:
(i) menstruation starts.
(ii) breasts start developing.
(iii) body weight increases.
(iv) height increases.

(c) The right meal for adolescents consists of:
(i) chips, noodles, coke.
(ii) chapati, dal, vegetables.
(iii) rice, noodles and burger.
(iv) vegetable cutlets, chips and lemon drink.
Answer:
(a) (ii)
(b) (i)
(c) (ii)

Chapter 11

Question 3.

Fill in the blanks in the following statements.

(a) To draw water from a well we have to ______ at the rope.

(b) A charged body ______ an uncharged body towards it.

(c) To move a loaded trolley we have to ______ it.

(d) The north pole of a magnet _______ the north pole of another magnet.

Answer:

(a) pull

(b) attracts

(c) push

(d) repels

Question 4.
An archer stretches her bow while taking aim at the target. She then releases the arrow, which begins to move towards the target. Based on this information fill up the gaps in the following statements using the following terms:
muscular, contact, non-contact, gravity, friction, shape, attraction
(a) To stretch the bow, the archer applies a force that causes a change in its ______
(b) The force applied by the archer to stretch the bow is an example of ______ force.
(c) The type of force responsible for a change in the state of motion of the arrow is an example of a ______ force.
(d) While the arrow moves towards its target, the forces acting on it are due to _______ and that due to _____ of air.
Answer:
(a) shape
(b) muscular
(c) contact
(d) gravity, friction

Question 7.

An inflated balloon was pressed against a wall after it has been rubbed with a piece of synthetic cloth. It was found that the balloon sticks to the wall. What force might be responsible for the attraction between the balloon and the wall?

Answer:

Electrostatic force.

Question 10.

When we press the bulb of a dropper with its nozzle kept in water, air in the dropper is seen to escape in the form of bubbles. Once we release the pressure on the bulb, water gets filled in the dropper. The rise of water in the dropper is due to

(a) pressure of water

(b) gravity of the earth

(c) shape of rubber bulb

(d) atmospheric pressure

Answer:

(d) atmospheric pressure

Chapter 12 "Friction"

Question 1.

Fill in the blanks.

(a) Friction opposes the ______ between the surfaces in contact with each other.

(b) Friction depends on the ______ of surfaces.

(c) Friction produces ______

(d) The sprinkling of powder on the carrom board _______ friction.

(e) Sliding friction is _______ than the static friction.

Solution:

(a) relative motion

(b) smoothness (or irregularities or nature)

(c) heat

(d) reduces

(e) less

Question 2.

Four children were asked to arrange forces due to rolling, static and sliding frictions in decreasing order. Their arrangements are given below. Choose the correct arrangement.

(a) rolling, static, sliding

(b) rolling, sliding, static

(c) static, sliding, rolling

(d) sliding, static, rolling

Solution:

(c) static, sliding, rolling.

Question 3.

Alida runs her toy car on a dry marble floor, wet marble floor, newspaper and towel spread on the floor. The force of friction acting on the car on different surfaces in increasing order will be

(a) wet marble floor, dry marble floor, newspaper and towel.

(b) newspaper, towel, dry marble floor, wet marble floor.

(c) towel, newspaper, dry marble floor, wet marble floor.

(d) wet marble floor, dry marble floor, towel, newspaper.

Answer:

(a) wet marble floor, dry marble floor, newspaper and towel.

Question 4.

Suppose your writing desk is tilted a little. A book kept on it starts sliding down. Show the direction of frictional force acting on it.

Answer:

Frictional force will act upward, i.e., the direction opposite to that of sliding book.

Chapter 13 "Sound"

Question 1.
Choose the correct answer.
Sound can travel through
(a) gases only
(b) solids only
(c) liquids only
(d) solids, liquids, and gases
Answer:
(d) solids, liquids, and gases.

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

Question 3.
In the following statements, tick ‘T’ against those which are true and ‘F’ against those which are false.

1. Sound cannot travel in a 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, the 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.

Answer:

1. True
2. False
3. False
4. True
5. False
6. False
7. True

Question 4.
Fill in the blanks with suitable words.

Time taken by an object to complete one oscillation is called _______

Loudness is determined by the ________ of vibration.

The unit of frequency is ________

Unwanted sound is called _______

The shrillness of a sound is determined by the ______ of vibration.

Answer:

Time period

Amplitude

Hertz (Hz)

Noise

Frequency

Question 7.
Identify the part which vibrates to produce sound in the following instruments.

Dholak

Sitar

Flute

Answer:

Stretched membrane

String of sitar

Air column

Chapter 14 "Chemical effects of electric current"

Question 1.

Fill in the blanks.

(a) Most liquids that conduct electricity are solutions of ______ , ______ and ______

(b) The passage of an electric current through a solution causes _______ effects.

(c) If you pass current through copper sulphate solution, copper gets deposited on the plate connected to the ________ terminal of the battery.

(d) The process of depositing a layer of any desired metal on another material by means of electricity is called _______

Answer:

(a) acids, bases, salts

(b) chemical

(c) negative

(d) electroplating

Question 5.

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

(i) liquid A is a better conductor than liquid B.

(ii) liquid B is a better conductor than liquid A.

(iii) both liquids are equally conducting.

(iv) conducting properties of liquid cannot be compared in this manner.

Answer:

(i) liquid A is a better conductor than liquid B

Chapter 15 "Some natural phenomena"

Select the correct option in Questions 1 and 2.

Question 1.

Which of the following cannot be changed easily by friction?

(a) A plastic scale

(b) A copper rod

(c) An inflated balloon

(d) A woollen cloth

Answer:

(b) A copper rod

Question 2.

When a glass rod is rubbed with a piece of silk cloth the rod

(a) and the cloth both acquire a positive charge.

(b) becomes positively charged while the cloth has a negative charge.

(c) and the cloth both acquire a negative charge.

(d) becomes negatively charged while the cloth has a positive charge

Answer:

(b) becomes positively charged while the cloth has a negative charge.

Question 3.

Write T against true and F against false in the following statements.

(a) Like charges attract each other.

(b) A charged glass rod attracts a charged plastic straw.

(c) Lightning conductor cannot protect a building from lightning.

(d) Earthquakes can be predicted in advance.

Answer:

(a) False

(b) True

(c) False

(d) False

Question 10.

List three states in India where earthquakes are more likely to strike.

Answer:

Kashmir, Rajasthan and Gujarat.

Chapter 16

Question 6.

Fill in the blanks in the following.

(a) A person 1 m in front of a plane mirror seems to be ______ m away from his image.

(b) If you touch your ______ ear with a right hand in front of a plane mirror it will be seen in the mirror that your right ear is touched with _____

(c) The size of the pupil becomes _______ when you see in dim light.

(d) Night birds have _______ cones than rods in their eyes.

Answer:

(a) 2

(b) left, left hand

(c) larger

(d) lesser

Choose the correct option in Questions 7-8.

Question 7.

The angle of incidence is equal to the angle of reflection

(a) Always

(b) Sometimes

(c) Under special conditions

(d) Never

Answer:

(a) Always

Question 8.

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.

Answer:

(b) virtual, behind the mirror and of the same size as the object.

Chapter 17

Choose the correct answer in Questions 1-3.
Question 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
Answer:
(c) A constellation

Question 2.
Which of the following is NOT a planet of the sun?
(a) Sirius
(b) Mercury
(c) Saturn
(d) Earth
Answer:
(a) SiriusQ

(a) we can see only that part of the moon which reflects light towards us.

Question 4.
Fill in the blanks.
(a) The planet which is farthest from the Sun is _____
(b) The planet which appears reddish in colour is ______
(c) A group of stars that appear to form a pattern in the sky is known as a _____
(d) A celestial body that revolves around a planet is known as ______
(e) Shooting stars are actually not _____
(f) Asteroids are found between the orbits of and ______
Answer:
(a) Neptune
(b) Mars
(c) constellation
(d) satellite
(e) stars
(f) Mars, Jupiter

Question 5.
Mark the following statements as true (T) or false (F).
(a) Pole star is a member of the solar system.
(b) Mercury is the smallest planet of the solar system.
(c) Uranus is the farthest planet in the solar system.
(d) INSAT is an artificial satellite.
(e) There are nine planets in the solar system.
(f) Constellation Orion can be seen only with a telescope.
Answer:
(a) False
(b) True
(c) False
(d) True
(e) False
(f) False

Question 6.
Match items in column A with one or more items in column B.

Inner planets-->. Earth and Mars
Outer planets--> Saturn
Constellation--> great bear and orion
Satellite of the earth--> moon

Question 7.
In which part of the sky can you find Venus if it is visible as an evening star?
Answer:
In west side of the sky.

Question 8.
Name the largest planet of the solar system.
Answer:
Jupiter

Question 11.
Name two objects other than planets which are members of the solar system.
Answer:
Comets and asteroids.

Chapter 18 Pollution

Question 7.
Which of the following is not a greenhouse gas?
(a) Carbon dioxide
(b) Sulphur dioxide
(c) Methane
(d) Nitrogen
Answer:
(d) Nitrogen

Class 6 Ques ans

 Chapter 1 food:- Where does it come from?

Q. 1. Do you find that all living beings need the same kind of food?
Ans. No, all living beings do not need same kind of food.

Q.2. Name five plants and their parts that we eat.
Ans. The names of five plants and their parts that we eat are:
(i) Paddy: seeds
(ii) Wheat: seeds
(iii) Mustard plant: seeds and leaves
(iv) Brinjal plant: fruits
(v) Potato plant: stems

Chapter 3:- " Fibre to fabric"

Q. 4. From which part of the plant cotton and jute are obtained?
Ans.
(i) Cotton – Cotton bolls (from the surface of cotton seeds) (fruit)
(ii) Jute – Stem

Q.5. Name two items that are made from coconut fibre.  
Ans.
(i) Ropes
(ii) Mats

Q.6. Explain the process of making yarn from fibre.
Ans. Yarns are made up of thin strands called fibres. The process of making yam from fibres is called spinning. In this process, a mass of cotton wool are drawn out and twisted. This brings the fibres together to form yarn.

Chapter 5 seperation of substances

1. Why do we need to separate different components of a mixture? Give two examples. 

Ans: Among different components of mixture there are many substances which are harmful or not useful for us. To remove these harmful or unuseful components we need to separate them. For example:

(a) Tea leaves are separated from the liquid with a strainer while preparing tea.

(b) Stone pieces from wheat, rice or pulses are picked out by hand.

2. What is winnowing? Where is it used?

Ans: Winnowing is used to separate heavier and lighter components of a mixture by wind or by blowing air. This process is used by farmers to separate lighter husk particles from heavier seeds of grain.

3.3.H will you separate husk or dirt particles from a given sample of pulses before cooking?

Ans: Husk or dirt particles can be separated by winnowing, being lighter they wall fly away from pulses.

4. What is Sieving? Where can it be used?

Ans. Sieving is a process by which fine particles are separated from bigger particles by using a sieve. It is used in flour mill or at construction sites. In flour mill, impurities like husks and stones are removed from wheat. Pebbles and stones are removed from sand by sieving

5.How will you separate sand and water from their mixture?

Ans. We will separate sand and water by sedimentation and decantation method. First we leave this mixture for some time. After some time, the sand which is; heavier is settled down at the bottom. After that we wall pour water into another container and the mixture will be separated.

6. Is it possible to separate sugar mixed with wheat flour? If yes, how will you do it?

Ans. Sugar can be separated from wheat flour by sieving. Due to difference in the size of particles, sugar will stay on sieve and wheat flour will pass through it.

7. How would you obtain clear water from a sample of muddy water?

Ans. We will obtain clear water from a sample of muddy water by the process of filtration.

10. Lemonade is prepared by mixing lemon juice and sugar in water. You wish to add ice to cool it. Should you add ice to the lemonade before or after dissolving sugar ? In which case would it be possible to dissolve more sugar ?

Ans. We should add ice after dissolving sugar. When the temperature is high then more sugar can be dissolved. After mixing ice it gets cool and less sugar will dissolve in it.

Chapter 5 "Seperation of Substances"

1. Why do we need to separate different components of a mixture? Give two examples. 

Ans: Among different components of mixture there are many substances which are harmful or not useful for us. To remove these harmful or unuseful components we need to separate them. For example:

(a) Tea leaves are separated from the liquid with a strainer while preparing tea.

(b) Stone pieces from wheat, rice or pulses are picked out by hand.

2. What is winnowing? Where is it used?

Ans: Winnowing is used to separate heavier and lighter components of a mixture by wind or by blowing air. This process is used by farmers to separate lighter husk particles from heavier seeds of grain.

How will you separate husk or dirt particles from a given sample of pulses before cooking?

Ans: Husk or dirt particles can be separated by winnowing, being lighter they wall fly away from pulses.

4. What is Sieving? Where can it be used?

Ans. Sieving is a process by which fine particles are separated from bigger particles by using a sieve. It is used in flour mill or at construction sites. In flour mill, impurities like husks and stones are removed from wheat. Pebbles and stones are removed from sand by sieving

. How will you separate sand and water from their mixture?

Ans. We will separate sand and water by sedimentation and decantation method. First we leave this mixture for some time. After some time, the sand which is; heavier is settled down at the bottom. After that we wall pour water into another container and the mixture will be separated.

Is it possible to separate sugar mixed with wheat flour? If yes, how will you do it?

Ans. Sugar can be separated from wheat flour by sieving. Due to difference in the size of particles, sugar will stay on sieve and wheat flour will pass through it.

7. How would you obtain clear water from a sample of muddy water?

Ans. We will obtain clear water from a sample of muddy water by the process of filtration.

. Lemonade is prepared by mixing lemon juice and sugar in water. You wish to add ice to cool it. Should you add ice to the lemonade before or after dissolving sugar ? In which case would it be possible to dissolve more sugar ?

Ans. We should add ice after dissolving sugar. When the temperature is high then more sugar can be dissolved. After mixing ice it gets cool and less sugar will dissolve in it.

Chap 10 "Motion and measurement of distances"

Give two examples each of modes of transport used on land, water and air.

Ans:

(i) Land—Bus, truck, train.

(ii) Water—Ship, boat.

(iii) Air—Aeroplane, Helicopter.

Why can a pace or a footstep not be used as a standard unit of length?

Ans: Because a pace or a footstep of each and every person is not equal.

5. The height of a person is 1.65 m. Express it in cm and mm.

Ans:

(a) 1.65 m, as one metre = 100 cm

= 1.65 x 100 cm = 165 cm

(b)65 x 100 x 10 mm = 1650 mm.

6. The distance between Radha’s home and her school is 3250 ,m. Express this distance in km.

Ans: 

7. While measuring the length of a knitting needle, the reading of the scale at one  end is 3.0 cm and at the other end is 33.1 cm. What is the length of the needle?

Ans:  Length of the needle = 33.1 cm – 3.0 cm = 30.1 cm.

8. Write the similarities and differences between the motion of a bicycle and a ceiling fan that has been switched on.

Ans: 

(i) Similarity: Both the wheel of a bicycle and a ceiling fan exhibit motion on a fixed axis.

(ii) Dissimilarity: Bicycle moves forward thus executes rectilinear motion but fan does not show such motion.

Why could you not use an elastic measuring tape to measure distance? What would be some of the problems you would meet in telling someone about a distance you measured with an elastic tape?

Ans:  An elastic measuring tape gives incorrect length of the distance between two points.

Reasons:

(i) The length of the elastic tape varies and depends upon the force by which it is stretched.

(ii) Measurement would vary between 2 or 3 readings even when measured by the same person and by the same elastic tape.

(iii) Measurement would also vary if different persons measure the same distance.

10. Give two examples of periodic motion.

Ans:

(i) Oscillations of a pendulum.

(ii) Motion of swing/motion of earth round the sun.

Class 6 back exercise

 Chapter 1 "Food : Where does it come from?"

Q. 3. Match the items given in column A with those in column B.

1. Milk , curd, paneer , ghee --> all are animal products

2. Spinach , Cauliflower, carrot --> are vegetables.

3. Lions and tigers --> eat other animals

4. Herbivores --> eat plants and plant products.

. 4. Fill up the blanks with the words given:
herbivore, plant, milk, sugarcane, carnivore.
(a) Tiger is a__________ because it eats only meat.
(b) Deer eats only plant products and so is called______________ .

(c) Parrot eats only__________

(d) The_________ that we drink, which comes from cows, buffaloes and goats is
an animal product.
(e) We get sugar from___________ .

Ans. (a) carnivore                                (b) herbivore            

(c) plant

(d) milk                             

(e) sugarcane

Chapter 2 " Components of food"

 1.Name the major nutrients in our food.
Ans: The major nutrients in our food are carbohydrates, proteins, fats, vitamins and minerals.

2. Name the following: 
(a) The nutrients which mainly give energy to our body.
(b) The nutrients that are needed for the growth and maintenance of our body.
(c) A vitamin required for maintaining good eyesight.
(d) A mineral that is required for keeping our bones healthy.

Ans:
(a) Carbohydrates
(b) Proteins
(c) Vitamin A
(d) Calcium

 3.Name two foods each rich in:
(a) Fats
(b) Starch
(c) Dietary fibre
(d) Protein
Ans:
(a) Ghee, butter,
(b) Raw potato, rice,
(c) Spinach, cabbage, carrot, ladies finger, (any two)
(d) Milk, egg, fish, meat, pulses (any two).

 4.Tick(✓) the statements that are correct, cross (X) those which dire incorrect.
(a) By eating rice alone, we can fulfill nutritional requirement of our body,
(b) Deficiency diseases can be prevented by eating a balanced diet.
(c) Balanced diet for the body should contain a variety of food items.
(d) Meat alone is sufficient to provide all nutrients to the body.

Ans:- (a) X (b) ✓ (c) ✓ (d) X

5.Fill in the blanks:
(a) ________ is caused by deficiency of Vitamin D. ,
(b) Deficiency of_________ causes a disease known as beri-beri.
(c) Deficiency of Vitamin C causes a disease known as________________ .
(d) Night blindness is caused due to deficiency of_______________ in our food.

Ans:
(a) Rickets
(b) Vitamin B1
(c) Scurvy
(d) Vitamin A

Chapter 3 Fibre to fabric

.2. State whether the following statements are ‘true’ or false’:
(a) Yam is made from fibres.
(b) Spinning is a process of making fibres.
(c) Jute is the outer covering of coconut.
(d) The process of removing seeds from cotton is called ginning.
(d) Weaving of yam makes a piece of fabric.
(e) Silk fibre is obtained from the stem of a plant.
(g) Polyester is a natural fibre.
Ans.
(a) True
(b) False
(c) False
(d) True
(e) True
(f) False
(g) False

Q.3. Fill in the blanks:
(a) Plant fibres are obtained from____________ and___________ .
(b) Animal fibres are___________ and___________ .
Ans.
(a) cotton plants, jute plants
(b) wool, silk

Chapter 4 Sorting Materials into groups

1. Name five objects which can be made from wood.

Ans.

(i) Table , (ii) Chair ,(iii) Doors ,(iv) Boat, (v) Bed

Q.2. Select those objects from the following which shine:

Glass bowl, plastic toy, steel spoon, cotton shirt

Ans. Glass bowl and steel spoon are shining objects.

Q.3. Match the objects given below with the materials from which they could be made. Remember, an object could be made from more than one material and a given material could be used for making many objects.

Book --> paper

Tumbler--> glass

Chair --> wood

Toy--> plastics

Shoes--> leather

Q. 4. State whether the statements given below are ‘true’ or ‘false’.

(i) Stone is transparent, while glass is opaque.

(ii) A notebook has lustre while eraser does not

(iii) Chalk dissolves in water.

(iv) A piece of wood floats on water.

(v) Sugar does not dissolve in water.

(vi) Oil mixes with water. 

(vii) Sand settles down in water.

(viii) Vinegar dissolves in water.

Ans.

(i) False , (ii) False , (iii) False , (iv) True , (v) False , (vi) False , (vii) True , (viii) True

Q. 5. Given below are the names of some objects and materials:

 Water, basket ball, orange, sugar, globe, apple and earthen pitcher Group them as:

(a) Round shaped and other shapes

(b) Eatables and non-eatables

Ans.

(a) (i) Round shaped: Basket ball, apple, orange, globe, earthen pitcher.

(ii) Other shapes: Water, sugar.

(b) (i) Eatables: Water, orange, sugar and apple.

(ii) Non-eatables: Basket ball, globe and earthen pitcher.

Q. 6. List all the items known to you that float on water. Check and see if they will float on an oil or kerosene.

Ans. (A) List of some items that float on water:

Paper, Wood, Thin plastic sheets, Wax, Ice ,Oil and Thermocol

(B) List of items that float on an oil:

Paper , Plastic sheet ,Wax, Thermocol, Wood

(C) List of items that float on kerosene:

Paper, Thermocol, Thin plastic sheet

Q. 7. Find the odd one out from the following:

(a) Chair, Bed, Table, Baby, Cupboard

(b) Rose, Jasmine, Boat, Marigold, Lotus

(c) Aluminium, Iron, Copper, Silver, Sand

(d) Sugar, Salt, Sand, Copper sulphate

Ans.

(a) Baby (all others are non-living)

(b) Boat (all others are flowers)

(c) Sand (all others are metals)

(d) Sand (all others are soluble in water)

Chapter 5

8. Fill in the blanks:
(a) The method of separating seeds of paddy from its stalks is called .
(b) When milk, cooled after boiling, is poured onto a piece of cloth the cream (malai) is left behind on it. This process of separating cream from milk is an example of ______. 
(a) Salt is obtained from sea water by the process of ____________ .
(b) Impurities settled at the bottom when muddy water was kept overnight in a bucket. The clear water was then poured off from the top. The process of separation used in this example is called ____________.
Ans.
(a) threshing
(b)filtration
(b) evaporation
(d) sedimentation and decantation

 True or false?
(a) A mixture of milk and water can be separated by filtration.
(b) A mixture of powdered salt and sugar can be separated by the process of winnowing.
(c) Separation of sugar from tea can be done with filtration.
(d) Grain and husk can be separated with the process of decantation.
Ans.
(a) False
(b) False
(c) False
(d) False

Chapter 6 

1. To walk through a waterlogged area, you usually shorten the length of your dress by folding it. Can this change be reversed?

Ans: Yes, it can be reversed by unfolding the dress.

2. You accidentally dropped your favourite toy and broke it. This is a change you did not want. Can this change be reversed?

Ans: No, this change (breaking of toy) cannot be reversed.

3.Some changes are listed in the following table. For each change, write in the blank column, whether the change can be reversed or not.

6. A thick coating of a paste of Plaster of Paris (POP) is applied over the bandage on a fractured bone. It becomes hard on drying to keep the fractured bone immobilised. Can the change in POP be reversed?

Ans: No, the change in POP cannot be reversed since it is a chemical change.

7. A bag of cement lying in the open gets wet due to rain during the night. The next day the sun shines brightly. Do you think the changes, which have occurred in the cement, could be reversed?

Ans. No, these are irreversible chemical changes.

Chapter 7 

1.Correct the following statements and rewrite them in your notebook.

(a) Stem absorbs water and minerals from the soil.

(b) Leaves hold the plant upright.

(c) Roots conduct water to the leaves.

(d) The number of sepals and petals in a flower is always equal.

(e) If the sepals of a flower are joined together, its petals are also joined together,

(f) If the petals of a flower are joined together, then the pistil is joined to the petal.

Ans:a) Roots absorb water and minerals from the soil.

(b) Roots hold the plant upright.

(c) Stem conducts water to the leaves.

(d) The number of petals and sepals in a flower is usually equal.

(e) If the sepals of a flower are joined together, its petals are not necessarily joined together.

(f) If the petals of a flower are joined together, then the pistil is not necessarily joined to the petal.

3. Can you find a plant in your house or in your neighbourhood which has a long but a weak stem? Write its name. In which category would you classify it?

Ans: Yes, we find a money plant in our house. It is a climber.

5.Which of the following leaves have reticulate venation?

Wheat, tulsi, maize, grass, coriander (dhania), china rose.

Ans: Tulsi, china rose.

6. If a plant has fibrous root, what type of venation are its leaves likely to have? 

Ans: Parallel venation.

7. If a plant has leaves with reticulate venation, what kind of roots will it have?

Ans:Tap root.

Chapter 8 

Fill in the blanks:

(a) Joints of the bones help in the_____________ of the body.

(b) A combination of bones and cartilages forms the_______________ of the body.

(c) The bones at the elbow are joined by a______________

(d) The contraction of the____________ pulls the   bones  during  

Ans: 

(a) movement, (b) skeleton, (c) hinge, (d) muscle

2. Indicate ‘true’ and false’ among the following sentences:

(a) The movement and locomotion of all animals is exactly the same.

(b) The cartilages are harder than bones.

(c) The finger bones do not have joints.

(d) The fore arm has two bones.

(e) Cockroaches have an outer skeleton.

Ans: 

(a) False , (b) False , (c) False , (d) True , (e) True

Match the items in column I with one or more items of column II:

Upper jaw--> is an immovable joint

Fish --> have a streamlined body and have find on the body

Ribs --> protect the heart

Snail--> shows very slow movement

Cockroach--> can fly in the air.

Chapter 9

Fill in the blanks:

(a) The presence of specific features which enables a plant or an animal to live in a particular habitat is called___________ .

(b) The habitats of the plants and animals that live on land are called _________________ habitats.

(c)The habitats of plants and animals that live in water are called ____________________ habitats.

(d) Soil, water and air are the____________ factors of a habitats.

(e) Changes in our surroundings that make us respond to them are called

Ans: 

(a) adaptation

(b) terrestrial

(c) aquatic

(d) abiotic

(e) stimuli

4. Which of the things in the following list are non-living?

Ans: Plough, Mushrooms, Sewing machine, Radio, Boat, Water, Hyacinth, Earthworm. Plough, Sewing machine, Radio, Boat and water are non-living.

6.Which of the following non-living things were once part of a living thing?

Butter, Leather, Soil, Wool, Electric Bulb, Cooking Oil, Salt, Apple, Rubber.

Ans: Butter, Leather, Wool, Cooking oil, Apple and Rubber are the non-living things which were once part of a living thing.

Chap 10 motion and measurement of distances

2. Fill in the blanks:

(i) One metre is___________

(ii) Five kilometre is___________

(iii) Motion of a child on a swing is_____________ .

(iv) Motion of the needle of a sewing machine is_______________ .

(v) Motion of wheel of a bicycle is_____________ .

Ans:

(i) 100

(ii) 5000

(iii) periodic (oscillatory) motion

(iv) periodic oscillatory (v) circular

4. Arrange the following lengths in their increasing magnitude :

1 metre, 1 centimetre, 1 kilometre, 1 millimetre.

Ans: Ascending order of length:

1 millimetre < 1 centimetre < 1 metre < 1 kilometre

Chap 11

1. Rearrange the boxes given below to make a sentence that helps us understand opaque objects.

Ans:-

2. Classify the objects or materials given below as opaque, transparent or translucent and luminous or non-luminous:

Air, water, a piece of rock, a sheet of aluminium, a mirror, a wooden board, a sheet of polythene, a CD, smoke, a sheet of plane glass, fog, a piece of red hot iron, an umbrella, a lighted fluorescent tube, a wall, a sheet of carbon paper, the fame of a gas burner, a sheet of cardboard, a lighted torch, a sheet of cellophane, a wire mesh, kerosene stove, sun, firefly, moon.

Ans:

Chapter 12

1. Fill in the blanks:

(a) A device that is used to break an electric circuit is called_______________

(b) An electric cell has___________

Ans:

(a) switch , (b) two

2. Mark ‘True’ or ‘False’ for the following statements:

(a) Electric current can flow through metals.

(b) Instead of metal wires, a jute string can be used to make a circuit.

(c) Electric current can pass through a sheet of thermocol.

Ans:

(a) True , (b) False , (c) False

Chapter 13

Fill in the blanks in the following:

(i) Artificial magnets are made in different shapes such as_________ ,_______ and

(ii) The materials which are attracted towards a magnet are called_________

(iii) Paper is not a________

(iv) In olden days, sailors used to find direction by suspending a piece of 

(v) A magnet always has ________poles.

Ans:

(i) bar magnet, horse-shoe magnet and cylindrical magnet

(ii) magnetic materials

(iii) magnetic

(iv) bar magnet or lode stone

(v) two or a pair of

2. State whether the following statements are true or false:

(i) A cylindrical magnet has only one pole.

(ii) Natural magnets were discovered in Greece.

(iii) Similar poles of a magnet repel each other.

(iv) Maximum iron filings stick in the middle of a bar magnet when it is brought near them.

(v) Bar magnets always point towards North-South direction when suspended freely in air.

(vi) A compass can be used to find East-West direction at any place.

(vii) Rubber is a magnetic material.

Ans: 

(i) False

(ii) True

(iii) True

(iv) False

(v) True

(vi) True

(vii) False

4.  Column I shows different positions in which one pole of a magnet is placed near that of the other. Column II indicates the resulting action between them for each situation. Fill in the blanks.

10. A magnet was brought from different directions towards a toy boat that has been floating in water in a tub. Effect observed in each case is stated in Column I. Possible reason for the observed effects are mentioned in Column II. Match the statements given in Column I with those in Column II

Ans

Chapter 14

1.Fill up the blanks in the following:

(a) The process of changing of water into its vapour is called_______________ .

(b) The process of changing water vapour into water is called_____________ .

(c) No rainfall for a year or more may lead to _____________ in that region.

(d) Excessive rains may cause__________ .

Ans:

(a) evaporation or vaporisation , (b) condensation , (c) droughts , (d) flood

2. State for each of the following whether it is due to evaporation or condensation:

(a) Water drops appear on the outer surface of a glass containing cold water.

(b) Steam rising from wet clothes while they are ironed.

(c) Fog appearing on a cold winter morning.

(d) Blackboard dries up after wiping it.

(e) Steam rising from a hot girdle when water is sprinkled on it.

Ans: 

(a) condensation , (b) evaporation , (c) condensation ,(d) evaporation

3. Which of the following statements are “true”?

(a) Water vapour is present in air only during the monsoon.

(b) Water evaporates into air from oceans, rivers and lakes but not from the soil.

(c) The process of water changing into its vapour is called evaporation.

(d) The evaporation of water takes place only in sunlight.

(e) Water vapour condenses to form tiny droplets of water in the upper layers of air where it is cooler.

Ans: 

(a) False , (b) False , (c) True , (d) False , (e) True.

Chapter 15

2. Which gas in the atmosphere is essential for respiration?

Ans: Oxygen.

6. The layer of air around the earth is known as………………….

Ans: Atmosphere

7. The component of air used by green plants to make their food, is………………….

Ans: Carbon dioxide.

Chapter 16

Do  Ques Ans