CLASS 8 VIDEO ON AIR PRESSURE

CLASS 8 REVISION FRICTION

FRICTION

CLASS 8

REVISION

1.To sharpen the blade of a knife by rubbing it against a surface,
which of the following will be most suitable?
(a) stone (c) wooden block
(b) plastic block (d) glass block
2. A toy car released with the same initial speed will travel
farthest on
(a) muddy surface (c) cemented surface

(b) polished marble surface (d) brick surface
3.If we apply oil on door hinges, the friction will
(a) increase (c) disappear altogether

(b) decrease (d) will remain unchanged
4.Two blocks of iron of different masses are kept on a cemented
floor . Which one of them would require a

larger force to move it from the rest position?

5.Two boys are riding their bicycles on the same concrete road.
One has new tyres on his bicycle while the other has tyres that
are old and used. Which of them is more likely to skid while
moving through a patch of the road which has lubricating oil

spilled over it?

6.You might have noticed that when used for a long time, slippers

with rubber soles become slippery. Explain the reason.
7.We have two identical metal sheets. One of them is rubbed with
sand paper and the other with ordinary paper. The one rubbed

with sand paper shines more than the other. Give reason.

CLASS 8 FORCE AND PRESSURE REVISION

CLASS 8 

FORCE AND PRESSURE

REVISION

1.During dry weather, while combing hair, sometimes we experience
hair flying apart. The force responsible for this is
(a) force of gravity. (c) force of friction.

(b) electrostatic force. (d) magnetic force.

2.Two objects repel each other. This repulsion could be due to
(a) frictional force only
(b) electrostatic force only
(c) magnetic force only
(d) either a magnetic or an electrostatic force
3. Which one of the following forces is a contact force?
(a) force of gravity (c) magnetic force

(b) force of friction (d) electrostatic force

4.A ball of dough is rolled into a flat chapatti. Name the force
exerted to change the shape of the dough.

5. Where do we apply a force while walking?

6. During dry weather, clothes made of synthetic fibre often stick to
the skin. Which type of force is responsible for this phenomenon?
7. While sieving grains, small pieces fall down. Which force pulls
them down?
8. Does force of gravity act on dust particles?
9. A gas filled balloon moves up. Is the upward force acting on it
larger or smaller than the force of gravity?
10. Does the force of gravitation exist between two astronauts in
space?


SHORT ANSWER QUESTIONS
11.A chapati maker is a machine which converts balls of dough into

chapati’s. What effect of force comes into play in this process?
12.Fruits detached from a tree fall down due to force of gravity. We
know that a force arises due to interaction between two objects.
Name the objects interacting in this case.

13. A man is pushing a cart down a slope. Suddenly the cart starts

moving faster and he wants to slow it down. What should he do?

CLASS 7 ACIDS BASES AND SALTS REVISION

CLASS 7               ACIDS BASES AND SALTS

REVISION

I. Fill in the blanks:-

1. An acid is ____________ by a base .

2. Phenolphthalein is an __________ indicator.

II. Choose the correct option:-

1. A Soap Solution is –

a) Basic b) Acidic c) Alkaline d) Neutral

2. CO2 + H2O →

a) Sulphuric acid b)Nitric acid c) Carbonic acid d) None

III. Name the following:-

1. Soluble bases.

2. A Chemical used as a food preservative.

IV Define the following:-

 1. Neutralisation Reaction 2. Acid-Base Indicator

V Give Reasons:-

1. Sour things are not kept in metal pots

2.  Acids are sour in taste.

VI. Answer in 20 words :-

1 Name three mineral acids and give their formulae?

2 What is acid and base?

VIII Answer in 40 words:-

1. What are general properties of bases?

2. What are general properties of acids?

3. Name an acidic gas which is discharged into the atmosphere on the burning of fuels like coal

& natural gas. How is this gas formed.

IX Write one use of the following:-

1. Sulphuric acid.

2. Citric acid

3. Sodium Carbonate

4. Potassium Nitrate

5. Calcium phosphate

X.While playing in a park, a child was stung by a wasp. Some

elders suggested applying paste of baking soda and others

lemon juice as remedy. Which remedy do you think is

appropriate and why?

XI. Form a sentence using the following words – baking soda, ant

bite, moist, effect, neutralised, rubbing.

Fill the blanks in the following sentences

(a) Lemon juice and vinegar taste ___________ because they

contain ___________.

(b) Turmeric and litmus are _________ acid-base indicators.

(c) Phenolphthalein gives _________ colour with lime water.

(d) When an acidic solution is mixed with a basic solution,

they _________ each other forming _________ and water.

XII.You are provided with three test tubes A, B and C as shown in

 with different liquids. What will you observe when

you put

(a) a piece of blue litmus paper in each test tube.

(b) a piece of red litmus paper in each test tube.

(c) a few drops of phenolphthalein solution to each test tube.

Test tube A contain solution of tartaric acid.

Test tube B contain soap solution .

Test tube C contain pure water.

LIVING AND NON-LIVING REVISION CLASS 6

LIVING AND NON LIVING 

REVISION

I. Answer the following questions:

1. What are living things?

2. What are non-living things?

3. What are natural things?

4. What are man-made things?

5. Give two examples of living things.

6. Give two examples of non-living things.

7. Give two examples of natural things.

8. Give two examples of man-made things.

9. What are the five differences between living things and non-living things?

10. Write six features of living things.

II. Fill in the blanks with the correct words:

1. All plants and _________ are living things. (animals/wood)

2. Most plants grow from _________. (seeds/eggs)

3. Non-living things found in nature are called _________ things. (man-made/natural)

4. Non-living things made by man are called _________ things. (man-made/natural)

5. Animals lay _________ or give birth to young ones. (seeds/eggs)

III. Define the following terms.

a. Stimulus    b. Excretion       c. Respiration.            d.Locomotion and movement.

CLASS 8 REVISION CELL STRUCTURE AND FUNCTIONS.

CELL  STRUCTURE AND FUNCTIONS.

REVISION

VERY SHORT ANSWER QUESTIONS

1. In leaves, name the cell organelle and pigment that is responsible
for green colour.
2. The instrument used to observe cells is ________
3. We do not sense any pain when we clip our nails or cut our hair.
Why?
4. In a cell, where are the genes located?

5. Amoeba and Paramecium belong to which category of organisms?
6. What are the functions of cell wall in plant cells?

7.Read the following statements and write the appropriate term
against each statement.
A. I control the functions of a cell. Who am I? . .................
B. I am like a policeman. I do not allow anything and everything
to get in and out of the cell. Who am I? . .................
C. I transfer characters from parents to offsprings. Who am I?

..................

8.Fill in the blanks with the terms given in the box below:
Nucleus, chromosomes, cell wall, cell membrane, protoplasm,
cytoplasm, ribosome, cell organelles
The outermost layer of plant cells is the________________ (a) beneath which
is the______________ (b) . The term ____________(c) refers to the jelly-like substance
containing all the ___________(d) . The ________________(e) contains thread-like

structures called _________________(f) .

9.The size of the cells of an organism has no relation with the size

of its body. Do you agree? Give reason for your answer.
10. Identify the type of cell and write their functions.

CLASS 7 REVISION ELECTRIC CURRENT AND SIMPLE CIRCUITS.

ELECTRIC CURRENT AND SIMPLE CIRCUITS

REVISION

1. Which property of a conducting wire is utilized in making
electric fuse?
2. Name the device used these days in place of electric fuses in
electrical circuits.
3. Fill in the blanks:
(i) Our body is a ________________ of electricity.
(ii) An electric cell produces electricity from the __________
___________ in it.
(iii) In an electric circuit a fuse is a _________ _______ to
prevent possible fire.
(iv) A combination of two or more cells is called a _________.
4. Unscramble the following words:
(i) TBTAYER
(ii) SFEU
(iii) HTRCO
(iv) HICWTS
5. Paheli does not have a night lamp in her room. She covered
the bulb of her room with a towel in the night to get dim light.
Has she taken the right step? Give one reason to justify your
answer.
6. Why are compact fluorescent lamps (CFLs) preferred over
electric bulbs?
7. Why is an electric fuse required in all electrical appliances?

8.Name two electric devices for each where
 (i) heating effect of
current is used and 
(ii) magnetic effect of current is used.
9. Why do we cover plug pin holes which are within the reach of
children with cello tape or a plastic cover when not in use?
10. Boojho made an electromagnet by winding 50 turns of wire
over an iron screw. Paheli also made an electromagnet by
winding 100 turns over a similar iron screw. Which electro
magnet will attract more pins? Give reason.

11. How does the magnetic effect of electric current help in the
working of an electric bell? Explain with the help of a diagram.
12. Draw the symbols of the following circuit components.
(i) electric cell
(ii) switch in off position
(iii) electric bulb

(iv) battery

class 6 revision Changes around us

Changes around us

Revision

1.A piece of iron is heated till it becomes red-hot. It then becomes
soft and is beaten to a desired shape. What kind of changes

are observed in this process– reversible or irreversible?
2. Can we reverse the following changes? If yes, suggest the name
of the method.
(a) Water into water vapour
(b) Water vapour into water.
(c) Ice into water.

(d) Curd into milk.
3. Which of the following changes cannot be reversed?
(a) Blowing of a balloon
(b) Folding a paper to make a toy aeroplane
(c) Rolling a ball of dough to make roti
(d) Baking cake in an oven
(e) Drying a wet cloth
(f) Making biogas from cow dung
(g) Burning of a candle

4. Give one example in each case
(a) Change which occurs on heating but can be reversed.
(b) Change which occurs on heating but cannot be reversed.
(c) Change which occurs on cooling but can be reversed.
(d) Change which occurs on mixing two substances, but
can be reversed.
(e) Change which occurs on mixing two substances, but
cannot be reversed.

5. Identify the changes as physical or chemical changes

• burning wood         
• souring milk
• mixing acid and base
• digesting food
• cooking an egg
• heating sugar to form caramel
• baking a cake
• rusting of iron
•                                                      
• crumpling a sheet of aluminum foil
• melting an ice cube
• casting silver in a mold
• breaking a bottle
• boiling water
• evaporating alcohol
• shredding paper
• sublimation of dry ice into carbon dioxide vapour
• 
  
• 
  

CLASS 8 REVISION REACHING THE AGE OF ADOLESCENCE.

REACHING THE AGE OF ADOLESCENCE

REVISION

VERY SHORT ANSWER QUESTIONS

1. Unscramble the underlined words in the following sentences.
(a) Reproductive life of a woman lasts from hacreemn to
spauoemen.
(b) The development of a caterpillar to an adult butterfly is termed
as poommertaissh.
(c) The overgrowth of sumselc in xalnyr leads to the hoarse voice
in adolescent boys.
(d) Dannalier helps the body to adjust and fight the stress.
2. Complete the following sentences.
(a) In females, the uterine wall thickens to receive the __________.
(b) Endocrine glands release hormones directly into___________for
transportation to the __________.
(c) The sex hormones,_______________________ and estrogen are
responsible for the development of __________ characters.
(d) Release of sex hormones is under the control of a hormone
secreted from the __________.
3. Give a suitable word for each of the following statements.
(a) The site which responds to a hormone.
(b) Name of a gland which transports secretions through ducts.
(c) Chemicals which control changes at adolescence stage.
(d) It marks the beginning of reproductive period.
4. Name the hormone that is released by testes at the onset of
puberty.
5. Name the female hormone produced by ovaries that helps in
development of mammary glands.

6. Lila always eats only dal and rice in every meal. She often falls ill
and has become prone to diseases. Can you suggest changes in
her diet which can make her healthy and free from disease?
7. Mention any two features each that are seen in boys and girls
each to distinguish them from each other at puberty.
8. We should avoid taking medicines/drugs unless prescribed by a
doctor. Give reasons.
9. A few of Paheli’s classmates eat potato chips and burgers
regularly during the recess at school. Are they healthy eating
habits? Give reasons.
10. Read the statements given below and fill up the blanks with the
correct words listed in the box.
deep, ductless, nutrients, thyroxine
(a) The meal that includes all __________ is a balanced diet.
(b) Insufficient production of __________ in the tadpoles leads to
their incomplete development.
(c) Endocrine glands are also called __________ glands.

(d) After attaining puberty boys develop a__________ voice.

11. During adolescence, the body of boys and girls undergoes certain
changes. Given below are a few of those changes.
(a) Broad shoulders
(b) Wider chests
(c) Wider region below waist
(d) Development of muscles
(e) Development of mammary glands
(f) Growth of facial hair
(g) Acne and pimples on face
(h) Development of sex organs
(i) High-pitched voice

(j) Growth of pubic hair.

Categorise these changes into those that occur in boys and those

that occur in girls .

12. Name the hormone which would be released during the following
situations:
(a) a frightened person.
(b) growth of a child to adult.
(c) development of caterpillar to moth.

(d) development of tadpole to frog.

CLASS 7 REVISION TIME AND MOTION

TIME AND MOTION

REVISION

1.A bus travels 54 km in 90 minutes. calculate the speed of the bus.

2.If we denote speed by S, distance by D and time by T, the
relationship between these quantities is

3.A spaceship travels 36,000 km in one hour. Express its speed
in m/s.
4.If Boojho covers a certain distance in one hour and Paheli
covers the same distance in two hours, who travels in a higher
speed?

4.A car covers a distance of 100 km in 5 hour, calculate its speed.

5.A pendulum takes 20 second to complete 10 oscillations, calculate its time period.

6.If a vehicle cover a distance of 5 km every hour and travels for 5 hours, the time distance time graph for the given vehicle can be plotted as follows using the table given below:

distance in km    5       10         15         20         25

time in Hour         1        2           3          4           5

7. Complete the following:

60 second = _____________

60 ___________ = 1 hour

___________ = 1 day

7 day = ______________

365 days = 1 year

1 Decade = _____________.

CLASS 6 REVISION MOTION AND MEASUREMENT

MOTION AND MEASUREMENT

REVISION

VERY SHORT ANSWER QUESTIONS

1. Correct the following.
(i) The motion of a swing is an example of rectilinear motion.
(ii) 1m = 1000 cm
2. Fill in the blanks
 (i) Motion of an object or a part of it
around a fixed point is
known as ................ motion.
(ii) A body repeating its motion after certain interval of time
is in . ......... motion.
(iii) In rectilinear motion, object moves........... a . .......... line.
(iv) SI unit of length is . ..........
3. Write one example for each of the following type of motion.
(i) Rectilinear
(ii) Circular
(iii) Periodic
(iv) Circular and periodic

4. Four children measure the length of a table which was about
2 m. Each of them used different ways to measure it.
(i) Sam measured it with a half metre long thread.
(ii) Gurmeet measured it with a 15 cm scale from her
geometry box.
(iii) Reena measured it using her hand span.
(iv) Salim measured it using a 5 m long measuring tape.
Which one of them would get the most accurate length? Give
reason for your answer.

5. Match the events related to motion in Column I with the types
of motions given in Column II.

COLUMN I                                                    COLUMN II
(a) A moving wheel of a                               (i) Circular motion
sewing machine
(b) Movement of the hour hand in a clock   (ii) Rotational motion       


(c) A moving swing                                   (iii) Periodic motion

6. Boojho was riding in his bicycle along a straight road. He
classified the motion of various parts of the bicycle as (i)
rectilinear motion, 
(ii) circular motion and 
(iii) both rectilinear
as well as circular motion. 
Can you list one part of the bicycle

for each type of motion? Support your answer with reason.

METALS AND NONMETALS REVISION

METALS AND NON METALS

REVISION

1. Which of the following is not a metal?
(a) copper                 (c) aluminium
(b) sulphur               (d) iron
2. The substance that will be flattened on beating with a hammer is
(a) crystal of iodine             (c) piece of coal
(b) lump of sulphur             (d) zinc granule
3. Boojho has learnt that non-metals on beating with a hammer
are generally broken into pieces. Which of the following is a non-
metal?
(a) iron nail                       (c) copper plate
(b) aluminium wire           (d) piece of coal
4. Materials which can be drawn into wires are called ductile. Which
of the following is not a ductile material?
(a) silver             (c) sulphur
(b) copper           (d) aluminium
5. Metals are generally hard. Which of the following metals is an
exception and can be cut with a knife?
(a) iron                    (c) gold
(b) sodium              (d) magnesium
6. Metals are generally solid. Which of the following metals is in the
liquid state at room temperature?
(a) mercury                    (c) aluminium
(b) silver                        (d) sodium
7. Metals generally react with dilute acids to produce hydrogen gas.
Which one of the following metals does not react with dilute
hydrochloric acid?
(a) magnesium                  (c) iron
(b) aluminium                   (d) copper

8. Which of the following reacts with cold water vigorously?
(a) carbon                                                 (c) magnesium
(b) sodium                                                (d) sulphur
9. The metal which produces hydrogen gas on reaction with dilute
hydrochloric acid as well as sodium hydroxide solution is
(a) copper              (c) aluminium
(b) iron                  (d) sodium
10. Which of the following non-metals reacts and catches fire on
exposure to air?
(a) phosphorus              (c) sulphur
(b) nitrogen                    (d) hydrogen
11. Generally metallic oxides are basic and non-metallic oxides are
acidic in nature. Solution of which of the following oxides in
water will change the colour of blue litmus to red?
(a) sulphur dioxide                   (c) iron oxide
(b) magnesium oxide               (d) copper oxide
12. Which of the following property is not responsible for copper to
be used as electrical conduction wires?
(a) ductility                 (c) good conductor of electricity
(b) colour                    (d) it is solid

VERY SHORT ANSWER QUESTIONS
13. Name two soft metals which can be cut with a knife.
14. Which non-metal is essential for our life and all living beings
inhale it during breathing?
15. Name two major non-metals which are present in fertilisers and
enhance the growth of plants.

16. Which non-metal is used to disinfect water?

17. A purple coloured non-metal forms a brown solution in alcohol
which is applied on wounds as an antiseptic. Name the non-
metal.

18. Zinc sulphate forms a colourless solution in water. Will you
observe any colour on adding copper turning in it?

19. Why are bells made of metals?
20. Which liquid metal is used for making thermometers?
21. Which of the following metals can displace the other two metals
from their salt solutions?
zinc, iron, copper

SHORT ANSWER QUESTIONS

22. Paheli bought a statue made of copper. To her surprise it acquired
a dull green coating after a couple of months. Explain the reason.

23. In simple circuit you find that the bulb glows when an iron nail is
placed between two ends of wire. Complete the following sentences
on the bases of this fact.

(a) __________ is a metal.
(b) Metals are good __________ of electricity.
24. If in  the above circuit iron nail is replaced by a wooden stick, will the bulb
glow or not? Justify your answer.
25. Paheli prepared a blue coloured solution of copper sulphate in
beaker A and placed an iron nail in it. Boojho prepared a yellowish
green solution of ferrous sulphate in beaker B and placed a copper
wire in it. What changes will they observe in the two beakers

after an hour?
26. Fill in the blanks to complete the following paragraph.
The name of the product formed in the reaction of sulphur and
_____________ is sulphur dioxide gas. When sulphur dioxide is
dissolved in_________________, sulphurous acid is formed. The
sulphurous acid turns _____________ litmus paper to ____________.
Generally oxides of __________ are acidic in nature.
After completing the paragraph write two questions which you

can raise on the basis of this information.

SORTING MATERIALS INTO GROUPS

REVISION

1.An iron nail is kept in each of the following liquids. In which
case would it lose its shine and appear dull?
(a) Mustard oil (b) Soft drink
(c) Coconut oil (d) Kerosene
2. Pick one material from the following which is completely soluble
in water.
(a) Chalk powder (b) Tea leaves
(c) Glucose (d) Saw dust
3. You are provided with the following materials
(i) Magnifying glass (ii) Mirror
(iii) Stainless steel plate (iv) Glass tumbler
Which of the above materials will you identify as transparent?
(a) (i) and (ii) (b) (i) and (iii)
(c) (i) and (iv) (d) (iii) and (iv)
4. Boojho found a bag containing the following materials
(i) Mirror
(ii) Paper stained with oil
(iii) Magnet
(iv) Glass spectacles

Help Boojho in finding out the material(s) which is/are opaque.
(a) (i) only (b) (iv) only
(c) (i) and (iii) (d) (ii) and (iv)
5. While doing an activity in class, the teacher asked Paheli to
handover a transluscent material. Which among the following
materials will Paheli pick and give her teacher?
(a) Glass tumbler (b) Mirror
(c) Muslin cloth (d) Aluminium foil
6. Which pair of substances among the following would float in a
tumbler half filled with water?
(a) Cotton thread, thermocol
(b) Feather, plastic ball
(c) Pin, oil drops
(d) Rubber band, coin
7. Which among the following are commonly used for making a
safety pin?
(a) Wood and glass (b) Plastic and glass
(c) Leather and plastic (d) Steel and plastic
8. Which of the following materials is not lustrous?
(a) Gold (b) Silver
(c) Wood (d) Diamond
9. Which of the following statements is not true?
(a) Materials are grouped for convenience.
(b) Materials are grouped to study their properties.
(c) Materials are grouped for fun.

(d) Materials are grouped according to their uses.

10. Find the odd one out from the following
(a) Tawa (b) Spade
(c) Pressure cooker (d) Eraser
11. Which type of the following materials is used for making the
front glass (wind screen) of a car?
(a) Transparent
(b) Translucent
(c) Opaque
(d) All the above

VERY SHORT ANSWER QUESTIONS

12. It was Paheli’s birthday. Her grandmother gave her two gifts
made of metals, one old dull silver spoon and a pair of lustrous
gold earrings. She was surprised to see the difference in the
appearance of the two metals. Can you explain the reason for
this difference?
13. Mixtures of red chilli powder in water, butter in water, petrol
in water, and honey in water were given to Radha, Sudha,
Sofia and Raveena, respectively. Whose mixture is in solution
form?
14. On a bright sunny day, Shikha was playing hide and seek
with her brother. She hid herself behind a glass door. Do you
think her brother will be able to locate her. If yes, why? If no,
why not?
15. Take a small cotton ball and place it in a tumbler/bowl filled
with water. Observe it for atleast 10 minutes. Will it float or

sink in water and why?

16. Which among the following materials would you identify as
soft materials and why?
Ice, rubber band, leaf, eraser, pencil, pearl, a piece of wooden
board, cooked rice, pulses and fresh chapati.