Class 9 Science: Solutions of Sample Practice Question Paper- 7 PDF Download

 Page 1


  
 
CBSE IX | SCIENCE 
 Sample Paper – 7 Solution 
 
     
CBSE 
Class IX Science 
Sample Paper – 7 Solution  
                                                                                                                           
Section A 
 
1. Jersey and Brown Swiss 
 
2. Aspects involved in the cycling of nutrients: 
? Input of nutrients 
? Output of nutrients 
? Internal nutrient cycling 
 
Section B 
 
3. When the biotic components of the biosphere such as plants and animals interact with 
the abiotic components such as soil and water, constant transfer of food and energy 
takes place. The flow of energy is unidirectional, but the flow of nutrients is cyclic. This 
makes the biosphere a dynamic but stable system. 
 
OR 
 
Eutrophication is nutrient enrichment involving the addition of nitrates and phosphates 
to water bodies which results in the growth of aquatic plants, especially algae causing 
colouration of water known as algal bloom. Eutrophication leads to the depletion of 
dissolved oxygen in water resulting in killing of aquatic organisms such as fish.  
 
4. A ball weighs 15 N. Thus, it is has a mass of  
W = mg ? m = W = 15 = 1.5 kg 
                                    g      10 
       When at rest, the ball experiences potential energy.  
       Thus, PE = m × g × h = 1.5 × 10 × 30 = 450 joules 
       Energy experienced by the ball once it reaches the ground is called kinetic energy. 
 
5. Sedimentation and decantation methods are used to separate a mixture containing 
an insoluble solid in a liquid. In this method, the mixture is allowed to stand 
undisturbed for some time. The insoluble solid substance settles and a clear liquid is 
left standing. This clear liquid is called supernatant liquid. The solid substance that 
settles is called sediment. This entire process is known as sedimentation. 
Page 2


  
 
CBSE IX | SCIENCE 
 Sample Paper – 7 Solution 
 
     
CBSE 
Class IX Science 
Sample Paper – 7 Solution  
                                                                                                                           
Section A 
 
1. Jersey and Brown Swiss 
 
2. Aspects involved in the cycling of nutrients: 
? Input of nutrients 
? Output of nutrients 
? Internal nutrient cycling 
 
Section B 
 
3. When the biotic components of the biosphere such as plants and animals interact with 
the abiotic components such as soil and water, constant transfer of food and energy 
takes place. The flow of energy is unidirectional, but the flow of nutrients is cyclic. This 
makes the biosphere a dynamic but stable system. 
 
OR 
 
Eutrophication is nutrient enrichment involving the addition of nitrates and phosphates 
to water bodies which results in the growth of aquatic plants, especially algae causing 
colouration of water known as algal bloom. Eutrophication leads to the depletion of 
dissolved oxygen in water resulting in killing of aquatic organisms such as fish.  
 
4. A ball weighs 15 N. Thus, it is has a mass of  
W = mg ? m = W = 15 = 1.5 kg 
                                    g      10 
       When at rest, the ball experiences potential energy.  
       Thus, PE = m × g × h = 1.5 × 10 × 30 = 450 joules 
       Energy experienced by the ball once it reaches the ground is called kinetic energy. 
 
5. Sedimentation and decantation methods are used to separate a mixture containing 
an insoluble solid in a liquid. In this method, the mixture is allowed to stand 
undisturbed for some time. The insoluble solid substance settles and a clear liquid is 
left standing. This clear liquid is called supernatant liquid. The solid substance that 
settles is called sediment. This entire process is known as sedimentation. 
  
 
CBSE IX | SCIENCE 
 Sample Paper – 7 Solution 
 
     
The clear water (supernatant liquid) is then poured out carefully into another beaker, 
leaving the sediments undisturbed. This process is known as decantation. 
 
Section C 
6.   
a)  
                     
 
(b) Number of electrons in fully filled K shell = 2 
     Number of electrons in fully filled L shell = 8 
     Number of electrons in fully filled M shell = 8 
     So, the total number of electrons = 2 + 8 + 8 = 18 
 
(c) Maximum number of electrons which can be accommodated in a shell = 2n
2
 
      where n = shell number 
 
7.  
(a) Lungs: Cough and breathlessness 
(b) Liver: Nausea, vomiting and abdominal pain 
(c) Brain: Headache, vomiting, fits and unconsciousness 
 
OR 
 
It is more difficult to make antiviral medicines than antibiotics because viruses have 
biochemical mechanisms of their own. They enter the host cells and use the host’s 
machinery for their life processes. Therefore, antiviral medicines work against the host 
body rather than against the virus. Antibiotics block bacterial synthesis pathways 
without affecting the body because bacteria have and use their own metabolic 
pathways. Therefore, they do not affect the host body. 
 
8.   
(a) We perspire more in summer. Cotton being a good absorber of water helps in 
absorbing sweat and exposes it to the atmosphere for evaporation. When sweat 
evaporates from our body, it takes away the heat from our body. Thus, our body 
loses heat and gets cooled. 
Page 3


  
 
CBSE IX | SCIENCE 
 Sample Paper – 7 Solution 
 
     
CBSE 
Class IX Science 
Sample Paper – 7 Solution  
                                                                                                                           
Section A 
 
1. Jersey and Brown Swiss 
 
2. Aspects involved in the cycling of nutrients: 
? Input of nutrients 
? Output of nutrients 
? Internal nutrient cycling 
 
Section B 
 
3. When the biotic components of the biosphere such as plants and animals interact with 
the abiotic components such as soil and water, constant transfer of food and energy 
takes place. The flow of energy is unidirectional, but the flow of nutrients is cyclic. This 
makes the biosphere a dynamic but stable system. 
 
OR 
 
Eutrophication is nutrient enrichment involving the addition of nitrates and phosphates 
to water bodies which results in the growth of aquatic plants, especially algae causing 
colouration of water known as algal bloom. Eutrophication leads to the depletion of 
dissolved oxygen in water resulting in killing of aquatic organisms such as fish.  
 
4. A ball weighs 15 N. Thus, it is has a mass of  
W = mg ? m = W = 15 = 1.5 kg 
                                    g      10 
       When at rest, the ball experiences potential energy.  
       Thus, PE = m × g × h = 1.5 × 10 × 30 = 450 joules 
       Energy experienced by the ball once it reaches the ground is called kinetic energy. 
 
5. Sedimentation and decantation methods are used to separate a mixture containing 
an insoluble solid in a liquid. In this method, the mixture is allowed to stand 
undisturbed for some time. The insoluble solid substance settles and a clear liquid is 
left standing. This clear liquid is called supernatant liquid. The solid substance that 
settles is called sediment. This entire process is known as sedimentation. 
  
 
CBSE IX | SCIENCE 
 Sample Paper – 7 Solution 
 
     
The clear water (supernatant liquid) is then poured out carefully into another beaker, 
leaving the sediments undisturbed. This process is known as decantation. 
 
Section C 
6.   
a)  
                     
 
(b) Number of electrons in fully filled K shell = 2 
     Number of electrons in fully filled L shell = 8 
     Number of electrons in fully filled M shell = 8 
     So, the total number of electrons = 2 + 8 + 8 = 18 
 
(c) Maximum number of electrons which can be accommodated in a shell = 2n
2
 
      where n = shell number 
 
7.  
(a) Lungs: Cough and breathlessness 
(b) Liver: Nausea, vomiting and abdominal pain 
(c) Brain: Headache, vomiting, fits and unconsciousness 
 
OR 
 
It is more difficult to make antiviral medicines than antibiotics because viruses have 
biochemical mechanisms of their own. They enter the host cells and use the host’s 
machinery for their life processes. Therefore, antiviral medicines work against the host 
body rather than against the virus. Antibiotics block bacterial synthesis pathways 
without affecting the body because bacteria have and use their own metabolic 
pathways. Therefore, they do not affect the host body. 
 
8.   
(a) We perspire more in summer. Cotton being a good absorber of water helps in 
absorbing sweat and exposes it to the atmosphere for evaporation. When sweat 
evaporates from our body, it takes away the heat from our body. Thus, our body 
loses heat and gets cooled. 
  
 
CBSE IX | SCIENCE 
 Sample Paper – 7 Solution 
 
     
(b) On coming in contact with the cold glass of water, water vapour present in the air 
loses energy and gets converted to liquid, which can be seen as water droplets. 
(c) It feels cold as the spirit evaporates from the skin. When the spirit changes from the 
liquid state to the vapour state, it absorbs heat energy from the skin. The skin thus 
loses heat and feels cool. 
9. The stone is revolved in a circular motion, and thus, the displacement performed by the 
stone is zero because it repeatedly comes to its initial position. Thus, the work done on 
revolving the stone is 
W = F × s = 30 × (0) = 0 joule 
 
10.  ?
2
M.m
F = G
r
, 
where  F ? gravitational force  
G ? gravitational constant  
                       M, m ? masses of the two bodies 
                       r ? distance between the two bodies 
     The SI unit of gravitational constant G is Nm
2
/kg
2
. 
 
11.  The pressure is the ratio of force (F) exerted by a body to the area (A) upon which the 
body is exerting the force. Also, weight (W) is the force exerted by a body due to the 
Earth’s gravitational pull, i.e. F = W. 
  
?
?
? ? ? ?
2
W mg
Acceleration due to gravity (g) 10 m / s
W 30 10 300 N
 
 
?
??
? ? ? ? ?
? ? ?
2
2
2
 F= 300 N
A r 
 A= 3.14 (0.5) 3.14 0.25 0.785
300
 P 382.1 N/m
0.785
 
Pressure exerted by the block on the floor is 382.1 N/m
2
. 
 
OR 
 
??
?
?
7
8
time taken by the earth to revolve around sun(T) 3.15 10 seconds
mean distance between erath and sun is (r)=1.49  10 km
if the planet takes time T to complete one revolution (2 r)around sun then ,
the
?
? ? ? ?
??
?
??
? ? ? ? ?
8
7
87
1
2 r 2 3.14 1.49 10
 orbital velocity of earth is given by(v) 
T 3.15 10
9.35 10 10
v 2.96 10 29.6 km/s
3.15
 
 
Page 4


  
 
CBSE IX | SCIENCE 
 Sample Paper – 7 Solution 
 
     
CBSE 
Class IX Science 
Sample Paper – 7 Solution  
                                                                                                                           
Section A 
 
1. Jersey and Brown Swiss 
 
2. Aspects involved in the cycling of nutrients: 
? Input of nutrients 
? Output of nutrients 
? Internal nutrient cycling 
 
Section B 
 
3. When the biotic components of the biosphere such as plants and animals interact with 
the abiotic components such as soil and water, constant transfer of food and energy 
takes place. The flow of energy is unidirectional, but the flow of nutrients is cyclic. This 
makes the biosphere a dynamic but stable system. 
 
OR 
 
Eutrophication is nutrient enrichment involving the addition of nitrates and phosphates 
to water bodies which results in the growth of aquatic plants, especially algae causing 
colouration of water known as algal bloom. Eutrophication leads to the depletion of 
dissolved oxygen in water resulting in killing of aquatic organisms such as fish.  
 
4. A ball weighs 15 N. Thus, it is has a mass of  
W = mg ? m = W = 15 = 1.5 kg 
                                    g      10 
       When at rest, the ball experiences potential energy.  
       Thus, PE = m × g × h = 1.5 × 10 × 30 = 450 joules 
       Energy experienced by the ball once it reaches the ground is called kinetic energy. 
 
5. Sedimentation and decantation methods are used to separate a mixture containing 
an insoluble solid in a liquid. In this method, the mixture is allowed to stand 
undisturbed for some time. The insoluble solid substance settles and a clear liquid is 
left standing. This clear liquid is called supernatant liquid. The solid substance that 
settles is called sediment. This entire process is known as sedimentation. 
  
 
CBSE IX | SCIENCE 
 Sample Paper – 7 Solution 
 
     
The clear water (supernatant liquid) is then poured out carefully into another beaker, 
leaving the sediments undisturbed. This process is known as decantation. 
 
Section C 
6.   
a)  
                     
 
(b) Number of electrons in fully filled K shell = 2 
     Number of electrons in fully filled L shell = 8 
     Number of electrons in fully filled M shell = 8 
     So, the total number of electrons = 2 + 8 + 8 = 18 
 
(c) Maximum number of electrons which can be accommodated in a shell = 2n
2
 
      where n = shell number 
 
7.  
(a) Lungs: Cough and breathlessness 
(b) Liver: Nausea, vomiting and abdominal pain 
(c) Brain: Headache, vomiting, fits and unconsciousness 
 
OR 
 
It is more difficult to make antiviral medicines than antibiotics because viruses have 
biochemical mechanisms of their own. They enter the host cells and use the host’s 
machinery for their life processes. Therefore, antiviral medicines work against the host 
body rather than against the virus. Antibiotics block bacterial synthesis pathways 
without affecting the body because bacteria have and use their own metabolic 
pathways. Therefore, they do not affect the host body. 
 
8.   
(a) We perspire more in summer. Cotton being a good absorber of water helps in 
absorbing sweat and exposes it to the atmosphere for evaporation. When sweat 
evaporates from our body, it takes away the heat from our body. Thus, our body 
loses heat and gets cooled. 
  
 
CBSE IX | SCIENCE 
 Sample Paper – 7 Solution 
 
     
(b) On coming in contact with the cold glass of water, water vapour present in the air 
loses energy and gets converted to liquid, which can be seen as water droplets. 
(c) It feels cold as the spirit evaporates from the skin. When the spirit changes from the 
liquid state to the vapour state, it absorbs heat energy from the skin. The skin thus 
loses heat and feels cool. 
9. The stone is revolved in a circular motion, and thus, the displacement performed by the 
stone is zero because it repeatedly comes to its initial position. Thus, the work done on 
revolving the stone is 
W = F × s = 30 × (0) = 0 joule 
 
10.  ?
2
M.m
F = G
r
, 
where  F ? gravitational force  
G ? gravitational constant  
                       M, m ? masses of the two bodies 
                       r ? distance between the two bodies 
     The SI unit of gravitational constant G is Nm
2
/kg
2
. 
 
11.  The pressure is the ratio of force (F) exerted by a body to the area (A) upon which the 
body is exerting the force. Also, weight (W) is the force exerted by a body due to the 
Earth’s gravitational pull, i.e. F = W. 
  
?
?
? ? ? ?
2
W mg
Acceleration due to gravity (g) 10 m / s
W 30 10 300 N
 
 
?
??
? ? ? ? ?
? ? ?
2
2
2
 F= 300 N
A r 
 A= 3.14 (0.5) 3.14 0.25 0.785
300
 P 382.1 N/m
0.785
 
Pressure exerted by the block on the floor is 382.1 N/m
2
. 
 
OR 
 
??
?
?
7
8
time taken by the earth to revolve around sun(T) 3.15 10 seconds
mean distance between erath and sun is (r)=1.49  10 km
if the planet takes time T to complete one revolution (2 r)around sun then ,
the
?
? ? ? ?
??
?
??
? ? ? ? ?
8
7
87
1
2 r 2 3.14 1.49 10
 orbital velocity of earth is given by(v) 
T 3.15 10
9.35 10 10
v 2.96 10 29.6 km/s
3.15
 
 
  
 
CBSE IX | SCIENCE 
 Sample Paper – 7 Solution 
 
     
12. Given weight of water = 3.6 g 
Molecular weight of water = 16 + 2 = 18 g 
  
                                   
Given weight of carbon dioxide = 4.4 g 
       Molecular weight of carbon dioxide = 12 + 44 = 56 g 
                       
 
OR 
(a) Al2(SO4)3 - Aluminium sulphate 
(b) CaCl2  -  Calcium chloride 
(c) K2SO4  - Potassium sulphate 
 
13.  
(a) Apis mellifera is the exotic breed of honeybee which is used for the commercial 
production of honey. 
(b) Advantages of bee keeping: 
? It can be used as an additional income-generating activity. 
? Beehives are a source of wax which can be used for medicinal applications. 
(c) Two qualities of Samar: 
? He is a good observer. 
? He thinks scientifically and commercially. 
 
14. Different cells of our body assume different sizes and shapes to perform specific 
functions in the body. The human body is complex and requires a huge range of 
functions to be carried out. If all the cells in our body were of the same size, shape and 
volume, then they would all perform the same function and a multitude of other 
important functions cannot be carried out, making life impossible. 
 
15.  
(a) Soil erosion. It is the process of removal of the top layer of soil under the effect of 
strong winds and fast running water. 
(b) Tray A has mustard plants growing in it. The roots of the plants play an important 
role in holding the soil particles. As a result, less water flows out from Tray A. 
(c) The top layer of soil is considered the most important layer because it is rich in 
humus and living microorganisms which help in recycling of nutrients in the soil. 
 
Page 5


  
 
CBSE IX | SCIENCE 
 Sample Paper – 7 Solution 
 
     
CBSE 
Class IX Science 
Sample Paper – 7 Solution  
                                                                                                                           
Section A 
 
1. Jersey and Brown Swiss 
 
2. Aspects involved in the cycling of nutrients: 
? Input of nutrients 
? Output of nutrients 
? Internal nutrient cycling 
 
Section B 
 
3. When the biotic components of the biosphere such as plants and animals interact with 
the abiotic components such as soil and water, constant transfer of food and energy 
takes place. The flow of energy is unidirectional, but the flow of nutrients is cyclic. This 
makes the biosphere a dynamic but stable system. 
 
OR 
 
Eutrophication is nutrient enrichment involving the addition of nitrates and phosphates 
to water bodies which results in the growth of aquatic plants, especially algae causing 
colouration of water known as algal bloom. Eutrophication leads to the depletion of 
dissolved oxygen in water resulting in killing of aquatic organisms such as fish.  
 
4. A ball weighs 15 N. Thus, it is has a mass of  
W = mg ? m = W = 15 = 1.5 kg 
                                    g      10 
       When at rest, the ball experiences potential energy.  
       Thus, PE = m × g × h = 1.5 × 10 × 30 = 450 joules 
       Energy experienced by the ball once it reaches the ground is called kinetic energy. 
 
5. Sedimentation and decantation methods are used to separate a mixture containing 
an insoluble solid in a liquid. In this method, the mixture is allowed to stand 
undisturbed for some time. The insoluble solid substance settles and a clear liquid is 
left standing. This clear liquid is called supernatant liquid. The solid substance that 
settles is called sediment. This entire process is known as sedimentation. 
  
 
CBSE IX | SCIENCE 
 Sample Paper – 7 Solution 
 
     
The clear water (supernatant liquid) is then poured out carefully into another beaker, 
leaving the sediments undisturbed. This process is known as decantation. 
 
Section C 
6.   
a)  
                     
 
(b) Number of electrons in fully filled K shell = 2 
     Number of electrons in fully filled L shell = 8 
     Number of electrons in fully filled M shell = 8 
     So, the total number of electrons = 2 + 8 + 8 = 18 
 
(c) Maximum number of electrons which can be accommodated in a shell = 2n
2
 
      where n = shell number 
 
7.  
(a) Lungs: Cough and breathlessness 
(b) Liver: Nausea, vomiting and abdominal pain 
(c) Brain: Headache, vomiting, fits and unconsciousness 
 
OR 
 
It is more difficult to make antiviral medicines than antibiotics because viruses have 
biochemical mechanisms of their own. They enter the host cells and use the host’s 
machinery for their life processes. Therefore, antiviral medicines work against the host 
body rather than against the virus. Antibiotics block bacterial synthesis pathways 
without affecting the body because bacteria have and use their own metabolic 
pathways. Therefore, they do not affect the host body. 
 
8.   
(a) We perspire more in summer. Cotton being a good absorber of water helps in 
absorbing sweat and exposes it to the atmosphere for evaporation. When sweat 
evaporates from our body, it takes away the heat from our body. Thus, our body 
loses heat and gets cooled. 
  
 
CBSE IX | SCIENCE 
 Sample Paper – 7 Solution 
 
     
(b) On coming in contact with the cold glass of water, water vapour present in the air 
loses energy and gets converted to liquid, which can be seen as water droplets. 
(c) It feels cold as the spirit evaporates from the skin. When the spirit changes from the 
liquid state to the vapour state, it absorbs heat energy from the skin. The skin thus 
loses heat and feels cool. 
9. The stone is revolved in a circular motion, and thus, the displacement performed by the 
stone is zero because it repeatedly comes to its initial position. Thus, the work done on 
revolving the stone is 
W = F × s = 30 × (0) = 0 joule 
 
10.  ?
2
M.m
F = G
r
, 
where  F ? gravitational force  
G ? gravitational constant  
                       M, m ? masses of the two bodies 
                       r ? distance between the two bodies 
     The SI unit of gravitational constant G is Nm
2
/kg
2
. 
 
11.  The pressure is the ratio of force (F) exerted by a body to the area (A) upon which the 
body is exerting the force. Also, weight (W) is the force exerted by a body due to the 
Earth’s gravitational pull, i.e. F = W. 
  
?
?
? ? ? ?
2
W mg
Acceleration due to gravity (g) 10 m / s
W 30 10 300 N
 
 
?
??
? ? ? ? ?
? ? ?
2
2
2
 F= 300 N
A r 
 A= 3.14 (0.5) 3.14 0.25 0.785
300
 P 382.1 N/m
0.785
 
Pressure exerted by the block on the floor is 382.1 N/m
2
. 
 
OR 
 
??
?
?
7
8
time taken by the earth to revolve around sun(T) 3.15 10 seconds
mean distance between erath and sun is (r)=1.49  10 km
if the planet takes time T to complete one revolution (2 r)around sun then ,
the
?
? ? ? ?
??
?
??
? ? ? ? ?
8
7
87
1
2 r 2 3.14 1.49 10
 orbital velocity of earth is given by(v) 
T 3.15 10
9.35 10 10
v 2.96 10 29.6 km/s
3.15
 
 
  
 
CBSE IX | SCIENCE 
 Sample Paper – 7 Solution 
 
     
12. Given weight of water = 3.6 g 
Molecular weight of water = 16 + 2 = 18 g 
  
                                   
Given weight of carbon dioxide = 4.4 g 
       Molecular weight of carbon dioxide = 12 + 44 = 56 g 
                       
 
OR 
(a) Al2(SO4)3 - Aluminium sulphate 
(b) CaCl2  -  Calcium chloride 
(c) K2SO4  - Potassium sulphate 
 
13.  
(a) Apis mellifera is the exotic breed of honeybee which is used for the commercial 
production of honey. 
(b) Advantages of bee keeping: 
? It can be used as an additional income-generating activity. 
? Beehives are a source of wax which can be used for medicinal applications. 
(c) Two qualities of Samar: 
? He is a good observer. 
? He thinks scientifically and commercially. 
 
14. Different cells of our body assume different sizes and shapes to perform specific 
functions in the body. The human body is complex and requires a huge range of 
functions to be carried out. If all the cells in our body were of the same size, shape and 
volume, then they would all perform the same function and a multitude of other 
important functions cannot be carried out, making life impossible. 
 
15.  
(a) Soil erosion. It is the process of removal of the top layer of soil under the effect of 
strong winds and fast running water. 
(b) Tray A has mustard plants growing in it. The roots of the plants play an important 
role in holding the soil particles. As a result, less water flows out from Tray A. 
(c) The top layer of soil is considered the most important layer because it is rich in 
humus and living microorganisms which help in recycling of nutrients in the soil. 
 
  
 
CBSE IX | SCIENCE 
 Sample Paper – 7 Solution 
 
     
Section D 
16. (a)  
(i) Molluscs: Garden snail, sea mussel 
(ii) Arachnids: Scorpion, spider  
(iii) Echinoderms: Sea urchin, star fish 
 (b) 
? Cold-blooded animals: Rohu, salamander 
? Warm-blooded animals: Bat, pigeon 
 
17. (a) 
        
??
?
Work (W) done by a force (F) is given by
W = F s Cos
The force applied on the trolley= 30 N 
displacement of the trolley= 20 metres
the angle made by pulley with the horizontal surf 30
the total
ace =
 wor ?
? ? ? ? ? ? ? ? ?
k done by man(W)= 30  20 cos 30
3
W 30 20 30 10 3 30 10 1.732 519.6 Joule
2
 
(b)  Power is the rate at which the work is done or energy is consumed. 
It is a scalar quantity as it only depends on the magnitude but not on the direction. 
 
OR 
(a)  
i. In case of an electron revolving in a circular orbit of radius ‘r’ around a nucleus, 
centripetal force provided by the electrostatic force of attraction acts on the 
electron towards the centre, but the motion is along the tangent to the circular 
orbit at each point. As force and displacement are mutually perpendicular to 
each other, the work done is zero. 
ii. In case of an electron moving with half the speed of light is free of all forces, 
work done will be zero as there is no force acting on the electron. 
 
(b) Height of the overhead tank ‘h’ = 20 m 
Mass of water to be raised ‘m’ = 2000 kg 
Time ‘t’ = 15 min = 15 ? 60 = 900 s 
??
? ? ? ?
Total work mgh 2000 9.8 20
Power of the pump 435.5 W
Total time t 900
 
Instantaneous power of a device at a particular instance of time is the rate of doing 
work by the device at that very instant.