Final Exam Class 9 Science Set 3 (Solutions) | Science Class 9 PDF Download

 Page 1


Section A
1. 
(b) R 
Explanation: Changes of state are examples of phase changes or phase transitions. All phase changes are accompanied by
changes in the energy of a system. The energy change in the phase transitions can be explained as follows:
Phase Change Name Phase Energy Change Example
Freezing Liquid to solid Exothermic Freezing water
Melting (P) Solid to liquid Endothermic Ice melting
Condensation (R) Gas to liquid Exothermic Water vapour burns
Evaporation (Q) Liquid to gas Endothermic Boiling water
Sublimation (S) Solid to gas Endothermic Dry ice
Deposition Gas to solid Exothermic Formation of frost
2. (a) Q 
Explanation: Sugar solution is hypertonic to cell sap of potato, whereas water acts as a hypotonic solution to it. When the
potato strip is placed in water, its cells will gain water by osmosis, resulting in increase in size of potato strip. When the potato
strips are put in sugar solution of different concentrations, the cells will lose water resulting in decrease in the size of strip. As
only potato strip placed in liquid ‘Q’ shows increase in length, this shows that liquid ‘Q’ is water.
3. (a) 50 
Explanation: Distance travelled in t
th
 second of uniformly accelerated motion is 
S
t
 = u + (2t - 1) ...(i) 
Distance travelled in (t + 1)
th
 second can be written as 
S
t+1
 = u + [2(t + 1) - 1] 
or S
t+1
 = u + (2t + 1) ...(ii) 
s
t
 + s
t+1
 = 100 cm (given) 
u + (2t -1) + u + (2t + 1) = 100 [Using (i) and (ii)] 
or 2u + 2at = 100 or u + at = 50; 
 v = 50 cms
-1
4. 
(c) Rice 
Explanation: Gundhi bugs are also called stink bugs as a characteristic foul odor is produced by scent glands present on the
abdomen. These stink bugs are distributed in all the tropical and sub-tropical regions. In India, it is used as a pest of all rice-
growing areas.  
5. 
(b) (i) and (iii) only 
Explanation: In plants, collenchyma is a permanent living tissue of primary body. It provides flexibility to soft aerial parts like
leaves, young stem of plant so that they can bend without breaking. Sclerenchyma consists of thick-walled, dead cells. It
provides hardness to the region where it occurs.  
6. (a) From solution 1 to solution 2 
Explanation: The movement of water from a region of its higher concentration to a region of its lower concentration through a
semi-permeable membrane is called osmosis. Since, concentration of water is high in solution 1, therefore, water will move
from solution 1 to solution 2 by the process of osmosis.
a 2 a 2 a 2 a 2 a 2 ? Solution
Page 8 of 14
Page 2


Section A
1. 
(b) R 
Explanation: Changes of state are examples of phase changes or phase transitions. All phase changes are accompanied by
changes in the energy of a system. The energy change in the phase transitions can be explained as follows:
Phase Change Name Phase Energy Change Example
Freezing Liquid to solid Exothermic Freezing water
Melting (P) Solid to liquid Endothermic Ice melting
Condensation (R) Gas to liquid Exothermic Water vapour burns
Evaporation (Q) Liquid to gas Endothermic Boiling water
Sublimation (S) Solid to gas Endothermic Dry ice
Deposition Gas to solid Exothermic Formation of frost
2. (a) Q 
Explanation: Sugar solution is hypertonic to cell sap of potato, whereas water acts as a hypotonic solution to it. When the
potato strip is placed in water, its cells will gain water by osmosis, resulting in increase in size of potato strip. When the potato
strips are put in sugar solution of different concentrations, the cells will lose water resulting in decrease in the size of strip. As
only potato strip placed in liquid ‘Q’ shows increase in length, this shows that liquid ‘Q’ is water.
3. (a) 50 
Explanation: Distance travelled in t
th
 second of uniformly accelerated motion is 
S
t
 = u + (2t - 1) ...(i) 
Distance travelled in (t + 1)
th
 second can be written as 
S
t+1
 = u + [2(t + 1) - 1] 
or S
t+1
 = u + (2t + 1) ...(ii) 
s
t
 + s
t+1
 = 100 cm (given) 
u + (2t -1) + u + (2t + 1) = 100 [Using (i) and (ii)] 
or 2u + 2at = 100 or u + at = 50; 
 v = 50 cms
-1
4. 
(c) Rice 
Explanation: Gundhi bugs are also called stink bugs as a characteristic foul odor is produced by scent glands present on the
abdomen. These stink bugs are distributed in all the tropical and sub-tropical regions. In India, it is used as a pest of all rice-
growing areas.  
5. 
(b) (i) and (iii) only 
Explanation: In plants, collenchyma is a permanent living tissue of primary body. It provides flexibility to soft aerial parts like
leaves, young stem of plant so that they can bend without breaking. Sclerenchyma consists of thick-walled, dead cells. It
provides hardness to the region where it occurs.  
6. (a) From solution 1 to solution 2 
Explanation: The movement of water from a region of its higher concentration to a region of its lower concentration through a
semi-permeable membrane is called osmosis. Since, concentration of water is high in solution 1, therefore, water will move
from solution 1 to solution 2 by the process of osmosis.
a 2 a 2 a 2 a 2 a 2 ? Solution
Page 8 of 14
7. 
(b) 50 g 
Explanation: The mass of one mole of CaCO
3
 is equal to 100 g. 6.022  10
23
 ions are equivalent to one mole. Therefore,
mass of 3.01  10
23 
ions will be equivalent to ( ) g or 50 g.  
8. (a) conducting tissue 
Explanation: The conducting tissues in plants conduct different saps and have different structures. The primary conducting
tissues of plants are xylem and phloem. Xylem conducts water from roots to the other parts of the plant, whereas phloem
transports food and other material from the leaves to other parts of plants.
9. 
(c) 20 cm
3
 
Explanation: 60 –  40 = 20 cm
3
  
10. 
(b) Velocity changes non-linearly if acceleration is changing linearly. 
Explanation: For the given graph, a = kt, where k is some positive constant. So, velocity v = u + at = u + (kt)t = 4 + kt
2
 i.e.,
varies non-linearly.  
11. 
(b) either metals or non-metals 
Explanation: Elements with valency 1 are easily loss or gain electron. So, elements with valency 1 are either metals or non-
metals. For example hydrogen is nonmetal and Lithium is metal both having valency 1.  
12. 
(b) parenchyma 
Explanation: Parenchyma cells containing chloroplasts are collectively termed as chlorenchyma. Special parenchyma tissue is
found in the aquatic plants and some land plants (e.g., petiole of Banana, Canna). It is known as aerenchyma. It consists of a
network of parenchyma cells that enclose very large air cavities.  
13. (a) ribosomes 
Explanation: Unlike eukaryotic cell, a prokaryotic cell lacks membrane-bound organelles like plastids, mitochondria and
endoplasmic reticulum but smaller and randomly scattered ribosomes are seen.
14. (a) starch 
Explanation: Many different food groups contain a carbohydrate known as starch. Using an iodine solution, you can test for
the presence of starch. When starch is present, the iodine changes from brown to blue-black or purple.
15. 
(d) Adding NaCl to water 
Explanation: Adding of common salt (NaCl) to water is physical change as no new substance is formed and no heat is evolved
during the addition of salt in water. Also, salt can be obtained by evaporation.   
16. 
(c) River lift 
Explanation: When it is not possible to supply enough water through a normal canal system, then a river lift system is utilized
to ensure a steady supply. This can happen in areas with uneven topography, or in areas which are far from a water reservoir.  
17. (a) Both A and R are true and R is the correct explanation of A. 
Explanation: Satellites revolve around their planets in almost circular orbits with constant speed. Thus, during their motion,
the speed remains constant, while the direction of motion changes continuously. As a result, there is a change in their velocity.
Therefore, the motion of satellites around their planets is considered as accelerated motion.
18. (a) Both A and R are true and R is the correct explanation of A. 
Explanation: The molecules of a gas are separated very far and there is a lot of empty space between them. Hence gases can
be compressed easily. In liquids molecules are closer to each other and can be brought further closer only under very high
pressure.
19. 
(b) Both A and R are true but R is not the correct explanation of A. 
Explanation: The functions of epithelial tissues are as follows: 
× × 1 0 0 2 Page 9 of 14
Page 3


Section A
1. 
(b) R 
Explanation: Changes of state are examples of phase changes or phase transitions. All phase changes are accompanied by
changes in the energy of a system. The energy change in the phase transitions can be explained as follows:
Phase Change Name Phase Energy Change Example
Freezing Liquid to solid Exothermic Freezing water
Melting (P) Solid to liquid Endothermic Ice melting
Condensation (R) Gas to liquid Exothermic Water vapour burns
Evaporation (Q) Liquid to gas Endothermic Boiling water
Sublimation (S) Solid to gas Endothermic Dry ice
Deposition Gas to solid Exothermic Formation of frost
2. (a) Q 
Explanation: Sugar solution is hypertonic to cell sap of potato, whereas water acts as a hypotonic solution to it. When the
potato strip is placed in water, its cells will gain water by osmosis, resulting in increase in size of potato strip. When the potato
strips are put in sugar solution of different concentrations, the cells will lose water resulting in decrease in the size of strip. As
only potato strip placed in liquid ‘Q’ shows increase in length, this shows that liquid ‘Q’ is water.
3. (a) 50 
Explanation: Distance travelled in t
th
 second of uniformly accelerated motion is 
S
t
 = u + (2t - 1) ...(i) 
Distance travelled in (t + 1)
th
 second can be written as 
S
t+1
 = u + [2(t + 1) - 1] 
or S
t+1
 = u + (2t + 1) ...(ii) 
s
t
 + s
t+1
 = 100 cm (given) 
u + (2t -1) + u + (2t + 1) = 100 [Using (i) and (ii)] 
or 2u + 2at = 100 or u + at = 50; 
 v = 50 cms
-1
4. 
(c) Rice 
Explanation: Gundhi bugs are also called stink bugs as a characteristic foul odor is produced by scent glands present on the
abdomen. These stink bugs are distributed in all the tropical and sub-tropical regions. In India, it is used as a pest of all rice-
growing areas.  
5. 
(b) (i) and (iii) only 
Explanation: In plants, collenchyma is a permanent living tissue of primary body. It provides flexibility to soft aerial parts like
leaves, young stem of plant so that they can bend without breaking. Sclerenchyma consists of thick-walled, dead cells. It
provides hardness to the region where it occurs.  
6. (a) From solution 1 to solution 2 
Explanation: The movement of water from a region of its higher concentration to a region of its lower concentration through a
semi-permeable membrane is called osmosis. Since, concentration of water is high in solution 1, therefore, water will move
from solution 1 to solution 2 by the process of osmosis.
a 2 a 2 a 2 a 2 a 2 ? Solution
Page 8 of 14
7. 
(b) 50 g 
Explanation: The mass of one mole of CaCO
3
 is equal to 100 g. 6.022  10
23
 ions are equivalent to one mole. Therefore,
mass of 3.01  10
23 
ions will be equivalent to ( ) g or 50 g.  
8. (a) conducting tissue 
Explanation: The conducting tissues in plants conduct different saps and have different structures. The primary conducting
tissues of plants are xylem and phloem. Xylem conducts water from roots to the other parts of the plant, whereas phloem
transports food and other material from the leaves to other parts of plants.
9. 
(c) 20 cm
3
 
Explanation: 60 –  40 = 20 cm
3
  
10. 
(b) Velocity changes non-linearly if acceleration is changing linearly. 
Explanation: For the given graph, a = kt, where k is some positive constant. So, velocity v = u + at = u + (kt)t = 4 + kt
2
 i.e.,
varies non-linearly.  
11. 
(b) either metals or non-metals 
Explanation: Elements with valency 1 are easily loss or gain electron. So, elements with valency 1 are either metals or non-
metals. For example hydrogen is nonmetal and Lithium is metal both having valency 1.  
12. 
(b) parenchyma 
Explanation: Parenchyma cells containing chloroplasts are collectively termed as chlorenchyma. Special parenchyma tissue is
found in the aquatic plants and some land plants (e.g., petiole of Banana, Canna). It is known as aerenchyma. It consists of a
network of parenchyma cells that enclose very large air cavities.  
13. (a) ribosomes 
Explanation: Unlike eukaryotic cell, a prokaryotic cell lacks membrane-bound organelles like plastids, mitochondria and
endoplasmic reticulum but smaller and randomly scattered ribosomes are seen.
14. (a) starch 
Explanation: Many different food groups contain a carbohydrate known as starch. Using an iodine solution, you can test for
the presence of starch. When starch is present, the iodine changes from brown to blue-black or purple.
15. 
(d) Adding NaCl to water 
Explanation: Adding of common salt (NaCl) to water is physical change as no new substance is formed and no heat is evolved
during the addition of salt in water. Also, salt can be obtained by evaporation.   
16. 
(c) River lift 
Explanation: When it is not possible to supply enough water through a normal canal system, then a river lift system is utilized
to ensure a steady supply. This can happen in areas with uneven topography, or in areas which are far from a water reservoir.  
17. (a) Both A and R are true and R is the correct explanation of A. 
Explanation: Satellites revolve around their planets in almost circular orbits with constant speed. Thus, during their motion,
the speed remains constant, while the direction of motion changes continuously. As a result, there is a change in their velocity.
Therefore, the motion of satellites around their planets is considered as accelerated motion.
18. (a) Both A and R are true and R is the correct explanation of A. 
Explanation: The molecules of a gas are separated very far and there is a lot of empty space between them. Hence gases can
be compressed easily. In liquids molecules are closer to each other and can be brought further closer only under very high
pressure.
19. 
(b) Both A and R are true but R is not the correct explanation of A. 
Explanation: The functions of epithelial tissues are as follows: 
× × 1 0 0 2 Page 9 of 14
i. The cells of epithelial tissue form the outer layer of the skin (body surface).
ii. The epithelial tissues inside the body form the lining of the mouth and alimentary canal and protect these organs by
secreting mucous. 
iii. They also help in the absorption of water and nutrients.
20. 
(c) A is true but R is false. 
Explanation: Electrons in different orbits have fixed energies.  
Section B
21. The mass of the balloon filled with helium is less than the mass of the air displaced by it. Hence upthrust acting on the balloon is
more than its weight. As a result the balloon experiences a net upthrust which makes it rise. As the balloon rises it experiences
lesser and lesser upthrust due to the fact that with height the density of air decreases. At a certain point the weight of the balloon
may be completely balanced by the upthrust acting on it. Thereafter the balloon stops rising.
OR
In such a case when the density of solid is exactly equal to that of the liquid, it will remain in equilibrium and keep floating in it.
The solid will float in such a way that the entire part of it will remain within the liquid, its upper surface coinciding with the liquid
surface.
22. In a pressure cooker, pressure is raised by preventing the vapours formed inside to escape from the closed cooker. This causes
water to boil at much higher temperature than its normal boiling point. Due to this reason, vegetables can be cooked better and
faster in a pressure cooker.
23. If the time gap between the original sound and reflected sound received by the listener is around 0.1s, only then the echo can be
heard.
Velocity of sound in air = 344 m/s.
Time interval = 0.1 s
Therefore, The minimum distance travelled by the reflected sound wave for the distinctly listening to the echo = Velocity of the
sound  Time interval = 344  0.1 = 34.5 m
Since, the girl is sitting in middle of a park of dimension 12 m ×12 m, Therefore; The distance travelled by the sound reflected
from the building and then reaching to the girl = (6 + 6) = 12 m, which is much smaller than the required distance. Therefore, Girl
will not hear any echo of sound.
24. Temperature on Kelvin scale = 25 + 273 
= 298 K 
Temperature on Fahrenheit scale = 
25. Mass of the vehicle (m) = 1500 kg 
Negative acceleration (a) = -1.7 ms
-2
 
 Force of friction between the road and vehicle 
F = ma 
F = 1500  (-1.7) 
= -2550 N 
Negative sign means force is acting in the direction opposite to the direction of motion of the vehicle.
OR
a. a stone of the same size will have more inertia than a rubber ball.
b. A train will have more inertia than a bicycle.
c. A five rupees coin will have more inertia than a one-rupee coin.
Explanation: Inertia is associated with mass. Inertia is directly proportional to the mass of a body. Objects having more mass have
more inertia.
26. Neils Bohr proposed a model of atom in 1912 to remove the drawbacks of Rutherford’s atomic model and to explain the structure
of an atom in detail. The features of Bohr’s model of atom are given below:- 
i) An electron revolves in the orbit of atom with well-defined energy. 
ii) Energy of orbits increases from the inner shell to the outer shells i.e. energy of orbit nearest to the nucleus is the lowest. 
iii) If energy is supplied to an electron, it moves from a lower orbit to a higher orbit. When an electron moves from a higher orbit
(energy level) to a lower orbit (energy level), energy is radiated as electromagnetic waves. 
iv) Each orbit or shell represents an energy level. Such orbits are represented as K,L,M,N,O (named starting from the centre of an
× × × 2 5 + 3 2 = F 9 5 7 7 0 ? × Page 10 of 14
Page 4


Section A
1. 
(b) R 
Explanation: Changes of state are examples of phase changes or phase transitions. All phase changes are accompanied by
changes in the energy of a system. The energy change in the phase transitions can be explained as follows:
Phase Change Name Phase Energy Change Example
Freezing Liquid to solid Exothermic Freezing water
Melting (P) Solid to liquid Endothermic Ice melting
Condensation (R) Gas to liquid Exothermic Water vapour burns
Evaporation (Q) Liquid to gas Endothermic Boiling water
Sublimation (S) Solid to gas Endothermic Dry ice
Deposition Gas to solid Exothermic Formation of frost
2. (a) Q 
Explanation: Sugar solution is hypertonic to cell sap of potato, whereas water acts as a hypotonic solution to it. When the
potato strip is placed in water, its cells will gain water by osmosis, resulting in increase in size of potato strip. When the potato
strips are put in sugar solution of different concentrations, the cells will lose water resulting in decrease in the size of strip. As
only potato strip placed in liquid ‘Q’ shows increase in length, this shows that liquid ‘Q’ is water.
3. (a) 50 
Explanation: Distance travelled in t
th
 second of uniformly accelerated motion is 
S
t
 = u + (2t - 1) ...(i) 
Distance travelled in (t + 1)
th
 second can be written as 
S
t+1
 = u + [2(t + 1) - 1] 
or S
t+1
 = u + (2t + 1) ...(ii) 
s
t
 + s
t+1
 = 100 cm (given) 
u + (2t -1) + u + (2t + 1) = 100 [Using (i) and (ii)] 
or 2u + 2at = 100 or u + at = 50; 
 v = 50 cms
-1
4. 
(c) Rice 
Explanation: Gundhi bugs are also called stink bugs as a characteristic foul odor is produced by scent glands present on the
abdomen. These stink bugs are distributed in all the tropical and sub-tropical regions. In India, it is used as a pest of all rice-
growing areas.  
5. 
(b) (i) and (iii) only 
Explanation: In plants, collenchyma is a permanent living tissue of primary body. It provides flexibility to soft aerial parts like
leaves, young stem of plant so that they can bend without breaking. Sclerenchyma consists of thick-walled, dead cells. It
provides hardness to the region where it occurs.  
6. (a) From solution 1 to solution 2 
Explanation: The movement of water from a region of its higher concentration to a region of its lower concentration through a
semi-permeable membrane is called osmosis. Since, concentration of water is high in solution 1, therefore, water will move
from solution 1 to solution 2 by the process of osmosis.
a 2 a 2 a 2 a 2 a 2 ? Solution
Page 8 of 14
7. 
(b) 50 g 
Explanation: The mass of one mole of CaCO
3
 is equal to 100 g. 6.022  10
23
 ions are equivalent to one mole. Therefore,
mass of 3.01  10
23 
ions will be equivalent to ( ) g or 50 g.  
8. (a) conducting tissue 
Explanation: The conducting tissues in plants conduct different saps and have different structures. The primary conducting
tissues of plants are xylem and phloem. Xylem conducts water from roots to the other parts of the plant, whereas phloem
transports food and other material from the leaves to other parts of plants.
9. 
(c) 20 cm
3
 
Explanation: 60 –  40 = 20 cm
3
  
10. 
(b) Velocity changes non-linearly if acceleration is changing linearly. 
Explanation: For the given graph, a = kt, where k is some positive constant. So, velocity v = u + at = u + (kt)t = 4 + kt
2
 i.e.,
varies non-linearly.  
11. 
(b) either metals or non-metals 
Explanation: Elements with valency 1 are easily loss or gain electron. So, elements with valency 1 are either metals or non-
metals. For example hydrogen is nonmetal and Lithium is metal both having valency 1.  
12. 
(b) parenchyma 
Explanation: Parenchyma cells containing chloroplasts are collectively termed as chlorenchyma. Special parenchyma tissue is
found in the aquatic plants and some land plants (e.g., petiole of Banana, Canna). It is known as aerenchyma. It consists of a
network of parenchyma cells that enclose very large air cavities.  
13. (a) ribosomes 
Explanation: Unlike eukaryotic cell, a prokaryotic cell lacks membrane-bound organelles like plastids, mitochondria and
endoplasmic reticulum but smaller and randomly scattered ribosomes are seen.
14. (a) starch 
Explanation: Many different food groups contain a carbohydrate known as starch. Using an iodine solution, you can test for
the presence of starch. When starch is present, the iodine changes from brown to blue-black or purple.
15. 
(d) Adding NaCl to water 
Explanation: Adding of common salt (NaCl) to water is physical change as no new substance is formed and no heat is evolved
during the addition of salt in water. Also, salt can be obtained by evaporation.   
16. 
(c) River lift 
Explanation: When it is not possible to supply enough water through a normal canal system, then a river lift system is utilized
to ensure a steady supply. This can happen in areas with uneven topography, or in areas which are far from a water reservoir.  
17. (a) Both A and R are true and R is the correct explanation of A. 
Explanation: Satellites revolve around their planets in almost circular orbits with constant speed. Thus, during their motion,
the speed remains constant, while the direction of motion changes continuously. As a result, there is a change in their velocity.
Therefore, the motion of satellites around their planets is considered as accelerated motion.
18. (a) Both A and R are true and R is the correct explanation of A. 
Explanation: The molecules of a gas are separated very far and there is a lot of empty space between them. Hence gases can
be compressed easily. In liquids molecules are closer to each other and can be brought further closer only under very high
pressure.
19. 
(b) Both A and R are true but R is not the correct explanation of A. 
Explanation: The functions of epithelial tissues are as follows: 
× × 1 0 0 2 Page 9 of 14
i. The cells of epithelial tissue form the outer layer of the skin (body surface).
ii. The epithelial tissues inside the body form the lining of the mouth and alimentary canal and protect these organs by
secreting mucous. 
iii. They also help in the absorption of water and nutrients.
20. 
(c) A is true but R is false. 
Explanation: Electrons in different orbits have fixed energies.  
Section B
21. The mass of the balloon filled with helium is less than the mass of the air displaced by it. Hence upthrust acting on the balloon is
more than its weight. As a result the balloon experiences a net upthrust which makes it rise. As the balloon rises it experiences
lesser and lesser upthrust due to the fact that with height the density of air decreases. At a certain point the weight of the balloon
may be completely balanced by the upthrust acting on it. Thereafter the balloon stops rising.
OR
In such a case when the density of solid is exactly equal to that of the liquid, it will remain in equilibrium and keep floating in it.
The solid will float in such a way that the entire part of it will remain within the liquid, its upper surface coinciding with the liquid
surface.
22. In a pressure cooker, pressure is raised by preventing the vapours formed inside to escape from the closed cooker. This causes
water to boil at much higher temperature than its normal boiling point. Due to this reason, vegetables can be cooked better and
faster in a pressure cooker.
23. If the time gap between the original sound and reflected sound received by the listener is around 0.1s, only then the echo can be
heard.
Velocity of sound in air = 344 m/s.
Time interval = 0.1 s
Therefore, The minimum distance travelled by the reflected sound wave for the distinctly listening to the echo = Velocity of the
sound  Time interval = 344  0.1 = 34.5 m
Since, the girl is sitting in middle of a park of dimension 12 m ×12 m, Therefore; The distance travelled by the sound reflected
from the building and then reaching to the girl = (6 + 6) = 12 m, which is much smaller than the required distance. Therefore, Girl
will not hear any echo of sound.
24. Temperature on Kelvin scale = 25 + 273 
= 298 K 
Temperature on Fahrenheit scale = 
25. Mass of the vehicle (m) = 1500 kg 
Negative acceleration (a) = -1.7 ms
-2
 
 Force of friction between the road and vehicle 
F = ma 
F = 1500  (-1.7) 
= -2550 N 
Negative sign means force is acting in the direction opposite to the direction of motion of the vehicle.
OR
a. a stone of the same size will have more inertia than a rubber ball.
b. A train will have more inertia than a bicycle.
c. A five rupees coin will have more inertia than a one-rupee coin.
Explanation: Inertia is associated with mass. Inertia is directly proportional to the mass of a body. Objects having more mass have
more inertia.
26. Neils Bohr proposed a model of atom in 1912 to remove the drawbacks of Rutherford’s atomic model and to explain the structure
of an atom in detail. The features of Bohr’s model of atom are given below:- 
i) An electron revolves in the orbit of atom with well-defined energy. 
ii) Energy of orbits increases from the inner shell to the outer shells i.e. energy of orbit nearest to the nucleus is the lowest. 
iii) If energy is supplied to an electron, it moves from a lower orbit to a higher orbit. When an electron moves from a higher orbit
(energy level) to a lower orbit (energy level), energy is radiated as electromagnetic waves. 
iv) Each orbit or shell represents an energy level. Such orbits are represented as K,L,M,N,O (named starting from the centre of an
× × × 2 5 + 3 2 = F 9 5 7 7 0 ? × Page 10 of 14
atom). 
v) The shell or orbits are associated with a certain amount of energy and energy of orbits/shells increases from the nucleus towards
the valence shell.
Section C
i. 27. Let P be the person standing between the cliffs A and B. Let s
1
 be a distance of nearest cliff A from P and s
2
 the distance of
second cliff B from P. The first echo is heard when sound reaches the person after being reflected from cliff A. 
Given, s
1
 = AP = 640 m 
Time interval of first echo, t
1
 = 4 seconds 
From relation, 2 s
1
 =  t
1
, we have 
The speed of sound,   
  
Therefore, Speed of sound in air, v = 320 m/s
ii. The second echo is heard when the sound reaches the person after being reflected from the cliff B. 
Time interval of second echo, t
2
 = 4 + 3 = 7 seconds 
Therefore, From relation, 2 s
2
 =  t
2
, 
We have,   
  
= 1120 m 
Therefore, Distance between cliffs A and B, 
s = s
1
 + s
2
 = 640 + 1120 = 1760 m
28. i. 
Particle Atomic number Mass number
A 3 3 + 4 = 7
B 9 9 + 8 = 17
C 8 8 + 8 = 16
D 8 8 + 10 = 18
ii. Particles C and D as they have same number of protons, i.e. same atomic number but different mass number.
a. 29. We know that area under v-t graph gives displacement. 
So, Area = distance (S) = area of triangle + area of rectangle 
Area of triangle =   
=   
= 30 m 
Area of rectangle = length  breadth 
= (16-6)  10 
=10  10 
= 100 m 
Total area = 100 + 30 = 130m 
Therefore distance covered by the runner in 16s = 130 m
b. Since, at t = 11 sec, runner is travelling with uniform velocity so, there is no change in velocity hence acceleration is zero.
OR
? ? = 2 s 1 t 1 2 × 6 4 0 4 ? ? t 2 2 3 2 0 × 7 2 × b a s e × h e i g h t 1 2 × 6 × 1 0 1 2 × × × Page 11 of 14
Page 5


Section A
1. 
(b) R 
Explanation: Changes of state are examples of phase changes or phase transitions. All phase changes are accompanied by
changes in the energy of a system. The energy change in the phase transitions can be explained as follows:
Phase Change Name Phase Energy Change Example
Freezing Liquid to solid Exothermic Freezing water
Melting (P) Solid to liquid Endothermic Ice melting
Condensation (R) Gas to liquid Exothermic Water vapour burns
Evaporation (Q) Liquid to gas Endothermic Boiling water
Sublimation (S) Solid to gas Endothermic Dry ice
Deposition Gas to solid Exothermic Formation of frost
2. (a) Q 
Explanation: Sugar solution is hypertonic to cell sap of potato, whereas water acts as a hypotonic solution to it. When the
potato strip is placed in water, its cells will gain water by osmosis, resulting in increase in size of potato strip. When the potato
strips are put in sugar solution of different concentrations, the cells will lose water resulting in decrease in the size of strip. As
only potato strip placed in liquid ‘Q’ shows increase in length, this shows that liquid ‘Q’ is water.
3. (a) 50 
Explanation: Distance travelled in t
th
 second of uniformly accelerated motion is 
S
t
 = u + (2t - 1) ...(i) 
Distance travelled in (t + 1)
th
 second can be written as 
S
t+1
 = u + [2(t + 1) - 1] 
or S
t+1
 = u + (2t + 1) ...(ii) 
s
t
 + s
t+1
 = 100 cm (given) 
u + (2t -1) + u + (2t + 1) = 100 [Using (i) and (ii)] 
or 2u + 2at = 100 or u + at = 50; 
 v = 50 cms
-1
4. 
(c) Rice 
Explanation: Gundhi bugs are also called stink bugs as a characteristic foul odor is produced by scent glands present on the
abdomen. These stink bugs are distributed in all the tropical and sub-tropical regions. In India, it is used as a pest of all rice-
growing areas.  
5. 
(b) (i) and (iii) only 
Explanation: In plants, collenchyma is a permanent living tissue of primary body. It provides flexibility to soft aerial parts like
leaves, young stem of plant so that they can bend without breaking. Sclerenchyma consists of thick-walled, dead cells. It
provides hardness to the region where it occurs.  
6. (a) From solution 1 to solution 2 
Explanation: The movement of water from a region of its higher concentration to a region of its lower concentration through a
semi-permeable membrane is called osmosis. Since, concentration of water is high in solution 1, therefore, water will move
from solution 1 to solution 2 by the process of osmosis.
a 2 a 2 a 2 a 2 a 2 ? Solution
Page 8 of 14
7. 
(b) 50 g 
Explanation: The mass of one mole of CaCO
3
 is equal to 100 g. 6.022  10
23
 ions are equivalent to one mole. Therefore,
mass of 3.01  10
23 
ions will be equivalent to ( ) g or 50 g.  
8. (a) conducting tissue 
Explanation: The conducting tissues in plants conduct different saps and have different structures. The primary conducting
tissues of plants are xylem and phloem. Xylem conducts water from roots to the other parts of the plant, whereas phloem
transports food and other material from the leaves to other parts of plants.
9. 
(c) 20 cm
3
 
Explanation: 60 –  40 = 20 cm
3
  
10. 
(b) Velocity changes non-linearly if acceleration is changing linearly. 
Explanation: For the given graph, a = kt, where k is some positive constant. So, velocity v = u + at = u + (kt)t = 4 + kt
2
 i.e.,
varies non-linearly.  
11. 
(b) either metals or non-metals 
Explanation: Elements with valency 1 are easily loss or gain electron. So, elements with valency 1 are either metals or non-
metals. For example hydrogen is nonmetal and Lithium is metal both having valency 1.  
12. 
(b) parenchyma 
Explanation: Parenchyma cells containing chloroplasts are collectively termed as chlorenchyma. Special parenchyma tissue is
found in the aquatic plants and some land plants (e.g., petiole of Banana, Canna). It is known as aerenchyma. It consists of a
network of parenchyma cells that enclose very large air cavities.  
13. (a) ribosomes 
Explanation: Unlike eukaryotic cell, a prokaryotic cell lacks membrane-bound organelles like plastids, mitochondria and
endoplasmic reticulum but smaller and randomly scattered ribosomes are seen.
14. (a) starch 
Explanation: Many different food groups contain a carbohydrate known as starch. Using an iodine solution, you can test for
the presence of starch. When starch is present, the iodine changes from brown to blue-black or purple.
15. 
(d) Adding NaCl to water 
Explanation: Adding of common salt (NaCl) to water is physical change as no new substance is formed and no heat is evolved
during the addition of salt in water. Also, salt can be obtained by evaporation.   
16. 
(c) River lift 
Explanation: When it is not possible to supply enough water through a normal canal system, then a river lift system is utilized
to ensure a steady supply. This can happen in areas with uneven topography, or in areas which are far from a water reservoir.  
17. (a) Both A and R are true and R is the correct explanation of A. 
Explanation: Satellites revolve around their planets in almost circular orbits with constant speed. Thus, during their motion,
the speed remains constant, while the direction of motion changes continuously. As a result, there is a change in their velocity.
Therefore, the motion of satellites around their planets is considered as accelerated motion.
18. (a) Both A and R are true and R is the correct explanation of A. 
Explanation: The molecules of a gas are separated very far and there is a lot of empty space between them. Hence gases can
be compressed easily. In liquids molecules are closer to each other and can be brought further closer only under very high
pressure.
19. 
(b) Both A and R are true but R is not the correct explanation of A. 
Explanation: The functions of epithelial tissues are as follows: 
× × 1 0 0 2 Page 9 of 14
i. The cells of epithelial tissue form the outer layer of the skin (body surface).
ii. The epithelial tissues inside the body form the lining of the mouth and alimentary canal and protect these organs by
secreting mucous. 
iii. They also help in the absorption of water and nutrients.
20. 
(c) A is true but R is false. 
Explanation: Electrons in different orbits have fixed energies.  
Section B
21. The mass of the balloon filled with helium is less than the mass of the air displaced by it. Hence upthrust acting on the balloon is
more than its weight. As a result the balloon experiences a net upthrust which makes it rise. As the balloon rises it experiences
lesser and lesser upthrust due to the fact that with height the density of air decreases. At a certain point the weight of the balloon
may be completely balanced by the upthrust acting on it. Thereafter the balloon stops rising.
OR
In such a case when the density of solid is exactly equal to that of the liquid, it will remain in equilibrium and keep floating in it.
The solid will float in such a way that the entire part of it will remain within the liquid, its upper surface coinciding with the liquid
surface.
22. In a pressure cooker, pressure is raised by preventing the vapours formed inside to escape from the closed cooker. This causes
water to boil at much higher temperature than its normal boiling point. Due to this reason, vegetables can be cooked better and
faster in a pressure cooker.
23. If the time gap between the original sound and reflected sound received by the listener is around 0.1s, only then the echo can be
heard.
Velocity of sound in air = 344 m/s.
Time interval = 0.1 s
Therefore, The minimum distance travelled by the reflected sound wave for the distinctly listening to the echo = Velocity of the
sound  Time interval = 344  0.1 = 34.5 m
Since, the girl is sitting in middle of a park of dimension 12 m ×12 m, Therefore; The distance travelled by the sound reflected
from the building and then reaching to the girl = (6 + 6) = 12 m, which is much smaller than the required distance. Therefore, Girl
will not hear any echo of sound.
24. Temperature on Kelvin scale = 25 + 273 
= 298 K 
Temperature on Fahrenheit scale = 
25. Mass of the vehicle (m) = 1500 kg 
Negative acceleration (a) = -1.7 ms
-2
 
 Force of friction between the road and vehicle 
F = ma 
F = 1500  (-1.7) 
= -2550 N 
Negative sign means force is acting in the direction opposite to the direction of motion of the vehicle.
OR
a. a stone of the same size will have more inertia than a rubber ball.
b. A train will have more inertia than a bicycle.
c. A five rupees coin will have more inertia than a one-rupee coin.
Explanation: Inertia is associated with mass. Inertia is directly proportional to the mass of a body. Objects having more mass have
more inertia.
26. Neils Bohr proposed a model of atom in 1912 to remove the drawbacks of Rutherford’s atomic model and to explain the structure
of an atom in detail. The features of Bohr’s model of atom are given below:- 
i) An electron revolves in the orbit of atom with well-defined energy. 
ii) Energy of orbits increases from the inner shell to the outer shells i.e. energy of orbit nearest to the nucleus is the lowest. 
iii) If energy is supplied to an electron, it moves from a lower orbit to a higher orbit. When an electron moves from a higher orbit
(energy level) to a lower orbit (energy level), energy is radiated as electromagnetic waves. 
iv) Each orbit or shell represents an energy level. Such orbits are represented as K,L,M,N,O (named starting from the centre of an
× × × 2 5 + 3 2 = F 9 5 7 7 0 ? × Page 10 of 14
atom). 
v) The shell or orbits are associated with a certain amount of energy and energy of orbits/shells increases from the nucleus towards
the valence shell.
Section C
i. 27. Let P be the person standing between the cliffs A and B. Let s
1
 be a distance of nearest cliff A from P and s
2
 the distance of
second cliff B from P. The first echo is heard when sound reaches the person after being reflected from cliff A. 
Given, s
1
 = AP = 640 m 
Time interval of first echo, t
1
 = 4 seconds 
From relation, 2 s
1
 =  t
1
, we have 
The speed of sound,   
  
Therefore, Speed of sound in air, v = 320 m/s
ii. The second echo is heard when the sound reaches the person after being reflected from the cliff B. 
Time interval of second echo, t
2
 = 4 + 3 = 7 seconds 
Therefore, From relation, 2 s
2
 =  t
2
, 
We have,   
  
= 1120 m 
Therefore, Distance between cliffs A and B, 
s = s
1
 + s
2
 = 640 + 1120 = 1760 m
28. i. 
Particle Atomic number Mass number
A 3 3 + 4 = 7
B 9 9 + 8 = 17
C 8 8 + 8 = 16
D 8 8 + 10 = 18
ii. Particles C and D as they have same number of protons, i.e. same atomic number but different mass number.
a. 29. We know that area under v-t graph gives displacement. 
So, Area = distance (S) = area of triangle + area of rectangle 
Area of triangle =   
=   
= 30 m 
Area of rectangle = length  breadth 
= (16-6)  10 
=10  10 
= 100 m 
Total area = 100 + 30 = 130m 
Therefore distance covered by the runner in 16s = 130 m
b. Since, at t = 11 sec, runner is travelling with uniform velocity so, there is no change in velocity hence acceleration is zero.
OR
? ? = 2 s 1 t 1 2 × 6 4 0 4 ? ? t 2 2 3 2 0 × 7 2 × b a s e × h e i g h t 1 2 × 6 × 1 0 1 2 × × × Page 11 of 14
a. (a) Acceleration =slope of the velocity time graph 
a =   
b. Distance =   
  
= 600-300 = 300m
c. 
30. (a) Social value, conceptual value, presence of mind. 
(b) Potential energy.
i. 31. Given mass, m = 50 g = kg. 
Acceleration during intervals 0 to 3 s = a
1
 =  =  = 40 m/s
2
 
According to Newton's second law of motion : Force, F
1
 = ma = ( )  40 = 2 N
ii. Acceleration during intervals 6 to 10 s = a
2
 =  =  = - = -30 m/s
2
 
Similarly, Force, F
2
 = ma
2
 = (-30) = -1.5 N.
iii. Time interval in which no force acts on the object ='3's - '6' s i.e A to B. 
This is because in this interval, the velocity of object is constant i.e. 120 m/s . 
Hence, Acceleration= '0' m/s
2
. Therefore, F= '0' N.
32. 
Prokaryotic cell Eukaryotic cell
Size : generally small ( 1-10 µm) where 1 µm = 10
-6
m
Size: generally large ( 5-100 µm)
Nuclear region: It is not well defined and known as the
nucleoid.
Nuclear region: well defined and surrounded by a nuclear
membrane
Chromosome: single More than one chromosome
Membrane-bound cell organelles absent Membrane-bound cell organelles are present.
OR
Animal cell Plant cell
Cell wall absent. Cell wall present.
Vacuoles are small. Vacuoles are large.
Chloroplast absent. Chloroplast present.
i. 33. Differentiation is the process by which meristematic tissue takes up a permanent shape, size and function.
ii. Large air cavities present in parenchyma (aerenchyma) of aquatic plants help the plant to maintain buoyancy in water.
iii. Epidermis of plants living in dry habitats are thicker in order to prevent loss of water.
a. iv. Xylem parenchyma consists of living cells having thin cell walls.
b. Phloem fibres are the dead element of phloem.
v. Tracheids and vessels of xylem are the two conducting tissues, which conduct water and minerals vertically.
Section D
34. A stone is dropped from the edge of a roof. 
Given, initial velocity  
Acceleration  m/s
2
- V 2 V 1 - t 2 t 1 a = = = - 6 m / 5 4 - 2 4 1 - 6 3 0 - 5 s 2 S = u t + a 1 2 t 2 = 6 0 × 1 0 + ( - 6 ) × 1 2 ( 1 0 ) 2 5 0 1 0 0 0 v - u t 1 2 0 - 0 3 5 0 1 0 0 0 × - v 2 v 1 t 0 - 1 2 0 ( 1 0 - 6 ) 1 2 0 4 5 0 1 0 0 0 × u = 0 g = 9 . 8 Page 12 of 14