Q1. Give any five examples of changes taking place in your daily life.
Ans. The examples of various changes are:
a) Germination of seeds
b) Growing of height
c) Inflating a balloon
d) Melting of ice
e) Burning of candle
Q2.What are the various types of changes?
Ans.
a) Slow & fast change
b) Reversible & irreversible change
c) Desirable & undesirable change
d) Physical & chemical change
Q3.Diiferentiate between reversible & irreversible change. Also give examples.
Ans. Reversible change: Those changes which can be reversed to the original form by
removing the cause of change are called reversible changes.
Example: melting of ice, stretching of rubber band, folding of paper etc.
Irreversible change: Those changes which cannot be reversed to the original form are
called irreversible changes.
Example: burning of candle, formation of flower to bud, bursting a balloon etc.
Q4. What are desirable & undesirable changes?
Ans. Desirable changes: Those changes which are desired to occur that is we want them
to take place are known as desirable changes.
Example: ripening of fruits, germination of seeds etc.
Undesirable change: Those changes which we do not want to take place are called
undesirable changes.
Example: rusting of iron, souring of milk, rottening of fruits etc.
Q5. Classify the following as reversible or irreversible changes:
a) Growth of a plant Irreversible change
b) Cooking of food Irreversible change
c) Melting of wax reversible change
d) Dissolving salt in water reversible change
Q6. How do following changes differ from each other:
a) Burning of wax
b) Melting of wax
Ans. Burning of wax is an irreversible change whereas melting of wax is an example of a
reversible change.
When we light a candle, then the wax present burns to produce various new substances
like carbon dioxide, water vapour, smoke etc. which cannot be combined together to give
back wax.
Also, solid wax on heating melts to form liquid wax which can be solidified again by
cooling it.
Q7.What are slow & fast changes? Give example.
Ans. Slow change: Those changes which take place in a long period of time are called
slow changes.
Example: rusting of iron, germination of seeds etc.
Fast change: Those changes which take place in a short time are called fast changes.
Example: burning of paper, bursting a balloon.
Q8. How is inflating a balloon different from bursting an inflated balloon?
Ans. Inflating a balloon is an example of a reversible change whereas bursting a balloon
is irreversible change.
When we blow air into a balloon, its shape & size changes. But it regains its original
form when the air is allowed to escape. On the other hand a bursted balloon cannot be
changed back to the original form.
Q9.Differentiate between physical & chemical change. Give 2 examples of each.
Ans.
Physical Change
Those changes in which no new substance is formed are called physical changes.
Physical changes are usually reversible.
Example: melting of wax, tearing of paper etc.
Chemical Change
Those changes in which a new substance with new chemical properties is formed are
known as chemical changes.
Chemical changes are irreversible.
Example: burning of paper, baking a chapatti etc.
Q10. Explain how, a metal wheel is fixed around the wooden wheel of a cart.
Ans. The iron rim is fixed around the wooden wheel of a cart by the process of expansion
on heating. The rim is made slightly smaller than the wooden wheel. On heating; the rim
expands & fits onto the wheel.
After that cold water is poured over the rim, as a result, it contracts & fits tightly onto the
wheel.Q11.Explain how, the iron blade of the digging objects like spade is fixed to a wooden
handle.
Ans. The iron is fixed by the process of expansion on heating.
The iron blade of tools has a ring in which the wooden handle is to be fixed. The ring is
slightly smaller than the handle. To fix the handle, the ring is heated & it expands. Now,
the handle easily fits on the ring. When the ring cools down then it contracts & fits tightly
on the handle.
Q12.When water is mixed with Plaster of Paris & allowed to dry, it sets into a hard mass.
State whether the change is reversible or irreversible. Justify your answer.
Ans. The above change is an example of an irreversible change. This is because when
water is added to Plaster of Paris then it sets as a hard mass & cannot be converted back
into the original form.
Q13. A bag of cement lying in the open gets wet due to rain. Can the change which takes
place in cement on getting wet be reversed by drying?
Ans. No, this change cannot be reversed on drying as some changes occur in cement on
getting wet due to which it gradually sets as a hard mass. Even if it is kept in bright
sunshine, then also the change cannot be reversed.
Q14. Milk can be changed into curd but curd cannot be changed back into milk. What is
the general name of such changes?
Ans. Such changes are known as irreversible changes.
Q15.How does a blacksmith change a piece of iron into different tools?
Ans. A blacksmith first heats a piece of iron till it becomes red hot. It then becomes soft
& can be beaten into desired shape.
Q16. You must have seen that construction workers heat a black material called coal tar
for repairing a road. State whether the change which has occurred in coal tar on being
heated is reversible or irreversible.
Ans. When coal tar is heated, it melts to form a thick dark liquid. The melting of coal tar
is a reversible change as it solidifies again on cooling.
Q17. Why is shaping of wet clay into clay pot a reversible change whereas baking a clay
pot an irreversible change?
Ans. The shaping of wet clay into a clay pot, a reversible change as wet clay can be
converted back into the original clay. Whereas a baked clay pot cannot be changed back
into the original form, therefore it is an irreversible change.
Ans. The examples of various changes are:
a) Germination of seeds
b) Growing of height
c) Inflating a balloon
d) Melting of ice
e) Burning of candle
Q2.What are the various types of changes?
Ans.
a) Slow & fast change
b) Reversible & irreversible change
c) Desirable & undesirable change
d) Physical & chemical change
Q3.Diiferentiate between reversible & irreversible change. Also give examples.
Ans. Reversible change: Those changes which can be reversed to the original form by
removing the cause of change are called reversible changes.
Example: melting of ice, stretching of rubber band, folding of paper etc.
Irreversible change: Those changes which cannot be reversed to the original form are
called irreversible changes.
Example: burning of candle, formation of flower to bud, bursting a balloon etc.
Q4. What are desirable & undesirable changes?
Ans. Desirable changes: Those changes which are desired to occur that is we want them
to take place are known as desirable changes.
Example: ripening of fruits, germination of seeds etc.
Undesirable change: Those changes which we do not want to take place are called
undesirable changes.
Example: rusting of iron, souring of milk, rottening of fruits etc.
Q5. Classify the following as reversible or irreversible changes:
a) Growth of a plant Irreversible change
b) Cooking of food Irreversible change
c) Melting of wax reversible change
d) Dissolving salt in water reversible change
Q6. How do following changes differ from each other:
a) Burning of wax
b) Melting of wax
Ans. Burning of wax is an irreversible change whereas melting of wax is an example of a
reversible change.
When we light a candle, then the wax present burns to produce various new substances
like carbon dioxide, water vapour, smoke etc. which cannot be combined together to give
back wax.
Also, solid wax on heating melts to form liquid wax which can be solidified again by
cooling it.
Q7.What are slow & fast changes? Give example.
Ans. Slow change: Those changes which take place in a long period of time are called
slow changes.
Example: rusting of iron, germination of seeds etc.
Fast change: Those changes which take place in a short time are called fast changes.
Example: burning of paper, bursting a balloon.
Q8. How is inflating a balloon different from bursting an inflated balloon?
Ans. Inflating a balloon is an example of a reversible change whereas bursting a balloon
is irreversible change.
When we blow air into a balloon, its shape & size changes. But it regains its original
form when the air is allowed to escape. On the other hand a bursted balloon cannot be
changed back to the original form.
Q9.Differentiate between physical & chemical change. Give 2 examples of each.
Ans.
Physical Change
Those changes in which no new substance is formed are called physical changes.
Physical changes are usually reversible.
Example: melting of wax, tearing of paper etc.
Chemical Change
Those changes in which a new substance with new chemical properties is formed are
known as chemical changes.
Chemical changes are irreversible.
Example: burning of paper, baking a chapatti etc.
Q10. Explain how, a metal wheel is fixed around the wooden wheel of a cart.
Ans. The iron rim is fixed around the wooden wheel of a cart by the process of expansion
on heating. The rim is made slightly smaller than the wooden wheel. On heating; the rim
expands & fits onto the wheel.
After that cold water is poured over the rim, as a result, it contracts & fits tightly onto the
wheel.Q11.Explain how, the iron blade of the digging objects like spade is fixed to a wooden
handle.
Ans. The iron is fixed by the process of expansion on heating.
The iron blade of tools has a ring in which the wooden handle is to be fixed. The ring is
slightly smaller than the handle. To fix the handle, the ring is heated & it expands. Now,
the handle easily fits on the ring. When the ring cools down then it contracts & fits tightly
on the handle.
Q12.When water is mixed with Plaster of Paris & allowed to dry, it sets into a hard mass.
State whether the change is reversible or irreversible. Justify your answer.
Ans. The above change is an example of an irreversible change. This is because when
water is added to Plaster of Paris then it sets as a hard mass & cannot be converted back
into the original form.
Q13. A bag of cement lying in the open gets wet due to rain. Can the change which takes
place in cement on getting wet be reversed by drying?
Ans. No, this change cannot be reversed on drying as some changes occur in cement on
getting wet due to which it gradually sets as a hard mass. Even if it is kept in bright
sunshine, then also the change cannot be reversed.
Q14. Milk can be changed into curd but curd cannot be changed back into milk. What is
the general name of such changes?
Ans. Such changes are known as irreversible changes.
Q15.How does a blacksmith change a piece of iron into different tools?
Ans. A blacksmith first heats a piece of iron till it becomes red hot. It then becomes soft
& can be beaten into desired shape.
Q16. You must have seen that construction workers heat a black material called coal tar
for repairing a road. State whether the change which has occurred in coal tar on being
heated is reversible or irreversible.
Ans. When coal tar is heated, it melts to form a thick dark liquid. The melting of coal tar
is a reversible change as it solidifies again on cooling.
Q17. Why is shaping of wet clay into clay pot a reversible change whereas baking a clay
pot an irreversible change?
Ans. The shaping of wet clay into a clay pot, a reversible change as wet clay can be
converted back into the original clay. Whereas a baked clay pot cannot be changed back
into the original form, therefore it is an irreversible change.
Chapter 5: Separation of substances
I. Fill in the blanks
1: Sand can be separated from water by the process of
_______________________________.
2: Common salt is obtained from sea water by the process
of __________________________.
3: Husk is separated from rice by the process of
_____________________________________.
4: Stones can be separated from rice by the process of
________________________________.
5: Grains can be separated from stalks by
__________________________________________.
6: To separate tea leaves from tea we use a
_________________________________________.
II. Answer in one word
1: Name the method used to separate pebbles or stones
from sand. ________________.
2: Name the method used to separate oil from
water. ______________________.
III. Define the following
1:
Threshing 2:
Handpicking 3:
Filtration 4: Saturated solution
IV. Distinguish between
1: Evaporation and condensation. 2:
Sedimentation and decantation.
V. How is common salt obtained from the sea
water? Explain.
VI. Draw and label the following
diagrams.
1: Process of filtration using a filter paper.
2: Process of Evaporation.
CHAPTER: 8 Body Movements
I) Fill in the blanks :
1. The bones are moved by alternate
_______ and of __________ of two sets of muscles.
2. Snails move with the help of muscular
___________________________.
3. Fish swim by forming __________
alternately on two sides of the body.
4. The body and legs of cockroaches have
hard coverings forming on outer ___________.
5. Snakes ________ on the ground by
looping sideways.
II) Distinguish between the following
:
1. Ball , socket joint and Hinge joint.
2. Bone and Cartilage.
III) Define
1. Skeleton
2. Ribcage
3. Joint
IV) Answer the
following questions :
1. Name
the different types of joints in our body.
2. Write the adaptation of a bird.
CHAPTER: 9 THE LIVING ORGANISMS AND THEIR SURROUNDINGS
I.Fill in the blanks:
1. Fish have ____________shaped body that
helps them to move inside water.
2. Small changes that take place in the
body of a living organism over a short period to overcome to some problems due
to changes in the surrounding are called ________________.
3. In the mountain regions, the trees are
normally ______________ shaped.
4. The process of producing more of their
own kind by the living organisms is called ________________.
5. Frogs have ____________feet that help
them to swim in water.
6. Dolphins and whales breathe through
_______________.
7. The process of getting rid of wastes
by the living organisms is called ________________.
8. The stems of aquatic plants are long,
______________ and _____________.
9. During respiration, organisms take
in _____________ and give out ___________.
10. Exchange of gases in plants take
place through the tiny pores on the leaves called ___.
II. Write true or false:
1. Several kinds of plants and animals
share the same habitat:
2. The light brown skin of the lion helps
it to become a predator in the grassland:
3. Desert animals like snakes and rats
come during the day:
4. The animals which cannot adapt to
changing abiotic factors of a region die out and only adapted ones survive:
5. Animals living in mountain regions
have thick skin or fur:
6. Plants donot show respond to stimuli:
7. Some plants remove some of their waste
products as secretions :
8. Camels excrete large amount of
urine and their dung is wet:
9. Plants carry out photosynthesis only
during the daytime and respiration only at night:
III. Name the following:
1. Two terrrestial habitats.
2. Two aquatic habitats.
3. Two plants and two animals of mountain regions
4. Four important abiotic factors needed for growth of
plants
5. Breathing organs of fish and earthworms.
6. Any three modes of reproduction by plants.
IV. Define the following:
i. Adaptation
ii. Stimuli
V. Distinguish between:
i. Biotic and abiotic factors.
ii.Terrestrial organisms and aquatic organisms.
VI. Draw, colour and label:
1) a desert
plant.
2) an aquatic plant
VII. PROJECT:
Stick pictures of any two plants and two animals
belonging to each of the following habitats:
1.
Deserts
2.
Mountain regions
3. Grasslands
4. Ponds/lakes.
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