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Science Class 9

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Class 9 : Notes | EduRev

 Page 1


  
 
CBSE IX | SCIENCE 
 Sample Paper – 4 Solution 
 
     
CBSE 
Class IX Science 
Sample Paper – 4 Solution  
                                                                                                                           
Section A 
 
1. The practice of growing different types of crops alternately in the same field in pre-
planned succession is called crop rotation.  
 
2. Conversion of inert elemental nitrogen gas into its biologically usable form is called 
nitrogen fixation. 
 
Section B 
 
3. Measures to prevent soil erosion: 
(a) Intensive cropping 
(b) Reforestation 
(c) Terrace farming 
OR 
Nutrient cycling in the ecosystem involves the following three aspects: 
(a) Input of nutrients 
(b) Output of nutrients 
(c) Internal nutrient cycling 
 
4. When a car is moving from rest, its initial velocity (u) is zero. 
The distance travelled (s) by this car can be found by using the second equation of 
motion. 
? ? ?
2
2
2
u = 0 m/s
a = 3 m/s
t = 9 min = 540 s
To find the distance we use
1
s = ut+ at
2
1
 s (0).540 (3).(540)
2
s = 437400 m = 437.4 km.
 
Therefore, the distance travelled by this car is 437.4 km. 
Calculating the speed of this car, 
Distance 437400
Speed =  =  = 810 m/s
time 540
 
The speed of this car is 810 m/s. 
Page 2


  
 
CBSE IX | SCIENCE 
 Sample Paper – 4 Solution 
 
     
CBSE 
Class IX Science 
Sample Paper – 4 Solution  
                                                                                                                           
Section A 
 
1. The practice of growing different types of crops alternately in the same field in pre-
planned succession is called crop rotation.  
 
2. Conversion of inert elemental nitrogen gas into its biologically usable form is called 
nitrogen fixation. 
 
Section B 
 
3. Measures to prevent soil erosion: 
(a) Intensive cropping 
(b) Reforestation 
(c) Terrace farming 
OR 
Nutrient cycling in the ecosystem involves the following three aspects: 
(a) Input of nutrients 
(b) Output of nutrients 
(c) Internal nutrient cycling 
 
4. When a car is moving from rest, its initial velocity (u) is zero. 
The distance travelled (s) by this car can be found by using the second equation of 
motion. 
? ? ?
2
2
2
u = 0 m/s
a = 3 m/s
t = 9 min = 540 s
To find the distance we use
1
s = ut+ at
2
1
 s (0).540 (3).(540)
2
s = 437400 m = 437.4 km.
 
Therefore, the distance travelled by this car is 437.4 km. 
Calculating the speed of this car, 
Distance 437400
Speed =  =  = 810 m/s
time 540
 
The speed of this car is 810 m/s. 
  
 
CBSE IX | SCIENCE 
 Sample Paper – 4 Solution 
 
     
5. Evaporation is a phenomenon of change of a liquid into vapour at any temperature 
below its boiling point. 
When evaporation occurs, the particles of the liquid absorb heat from the surrounding 
to regain the energy lost during evaporation. This absorption of energy from the 
surrounding makes the surrounding cool. 
 
Section C 
 
6. Drawbacks of Rutherford’s Model of an Atom: 
? Rutherford’s atomic model could not explain how moving electrons remain in their 
orbits. 
? Any charged particle during acceleration would radiate energy, and while revolving, 
it would lose its energy and eventually fall into the nucleus. 
? This means that the atom would be highly unstable. 
? But, matter is composed of stable atoms. 
? So, the major drawback of Rutherford’s atomic model was that it could not explain 
the stability of atoms. 
 
7.  
(a) Desirable characteristics can be incorporated into crop varieties by the following 
methods: 
? Hybridisation: Selected plants with one or more desirable traits are crossed with 
one another.  
? Genetic engineering: Desirable characteristics are introduced into selected 
plants with the help of techniques of biotechnology. 
(b) Crops are selected for intercropping based on different nutrient requirements and 
different sowing and harvesting patterns of crops, e.g. soybean and maize. 
OR 
Effects due to excessive irrigation of crops: 
? Soil erosion 
? Changes in the composition of soil due to solubilisation of some of the minerals 
from the soil 
? Water pollution 
Page 3


  
 
CBSE IX | SCIENCE 
 Sample Paper – 4 Solution 
 
     
CBSE 
Class IX Science 
Sample Paper – 4 Solution  
                                                                                                                           
Section A 
 
1. The practice of growing different types of crops alternately in the same field in pre-
planned succession is called crop rotation.  
 
2. Conversion of inert elemental nitrogen gas into its biologically usable form is called 
nitrogen fixation. 
 
Section B 
 
3. Measures to prevent soil erosion: 
(a) Intensive cropping 
(b) Reforestation 
(c) Terrace farming 
OR 
Nutrient cycling in the ecosystem involves the following three aspects: 
(a) Input of nutrients 
(b) Output of nutrients 
(c) Internal nutrient cycling 
 
4. When a car is moving from rest, its initial velocity (u) is zero. 
The distance travelled (s) by this car can be found by using the second equation of 
motion. 
? ? ?
2
2
2
u = 0 m/s
a = 3 m/s
t = 9 min = 540 s
To find the distance we use
1
s = ut+ at
2
1
 s (0).540 (3).(540)
2
s = 437400 m = 437.4 km.
 
Therefore, the distance travelled by this car is 437.4 km. 
Calculating the speed of this car, 
Distance 437400
Speed =  =  = 810 m/s
time 540
 
The speed of this car is 810 m/s. 
  
 
CBSE IX | SCIENCE 
 Sample Paper – 4 Solution 
 
     
5. Evaporation is a phenomenon of change of a liquid into vapour at any temperature 
below its boiling point. 
When evaporation occurs, the particles of the liquid absorb heat from the surrounding 
to regain the energy lost during evaporation. This absorption of energy from the 
surrounding makes the surrounding cool. 
 
Section C 
 
6. Drawbacks of Rutherford’s Model of an Atom: 
? Rutherford’s atomic model could not explain how moving electrons remain in their 
orbits. 
? Any charged particle during acceleration would radiate energy, and while revolving, 
it would lose its energy and eventually fall into the nucleus. 
? This means that the atom would be highly unstable. 
? But, matter is composed of stable atoms. 
? So, the major drawback of Rutherford’s atomic model was that it could not explain 
the stability of atoms. 
 
7.  
(a) Desirable characteristics can be incorporated into crop varieties by the following 
methods: 
? Hybridisation: Selected plants with one or more desirable traits are crossed with 
one another.  
? Genetic engineering: Desirable characteristics are introduced into selected 
plants with the help of techniques of biotechnology. 
(b) Crops are selected for intercropping based on different nutrient requirements and 
different sowing and harvesting patterns of crops, e.g. soybean and maize. 
OR 
Effects due to excessive irrigation of crops: 
? Soil erosion 
? Changes in the composition of soil due to solubilisation of some of the minerals 
from the soil 
? Water pollution 
  
 
CBSE IX | SCIENCE 
 Sample Paper – 4 Solution 
 
     
8.  
(a)When acetone is poured on the palm, it takes up the latent heat of vaporisation 
required to change from the liquid state to vapour state from our hand. The hand 
loses heat and gets cooled. 
(b)The earthen pot has small pores in its walls. Some of the water continuously seeps 
out from these pores. This water evaporates and absorbs heat of vaporisation from 
the remaining water. Thus, the remaining water loses heat and gets cooled. 
(c) Larger the surface area, faster will be the cooling. Evaporation is a surface 
phenomenon. The particles of tea on the surface absorb the heat for vaporisation 
from the remaining particles of the tea and evaporate. The tea thus loses heat and 
cools faster. 
 
9. Distance travelled by the pulse ‘s’ = 8 m 
Time taken ‘t’ = 0.05 s 
Frequency ‘ ?’ = 200 Hz 
(a) We know that 
 
distance s 8
v =  =  =  = 160 m/s
time t 0.05
 
Hence, the velocity of the pulse is 160 m/s. 
 
(b) We know that 
 
v = ??
v 160
? =  =  = 0.8 m
? 200
 
Hence, the wavelength of the pulse is 0.8 m. 
 
10. Force (F) acting between the Earth (mass M) and the stone of mass (m) separated by 
the distance (r) by the universal law of gravitation is given by the equation      
?
2
M.m
F = G
r
. 
The mass of stone is negligible (too less) when compared to the mass of the Earth which 
is 6 ? 10
24
 kg. Thus, the stone falls on the Earth and the Earth does not rise towards the Sun.  
 
  
Page 4


  
 
CBSE IX | SCIENCE 
 Sample Paper – 4 Solution 
 
     
CBSE 
Class IX Science 
Sample Paper – 4 Solution  
                                                                                                                           
Section A 
 
1. The practice of growing different types of crops alternately in the same field in pre-
planned succession is called crop rotation.  
 
2. Conversion of inert elemental nitrogen gas into its biologically usable form is called 
nitrogen fixation. 
 
Section B 
 
3. Measures to prevent soil erosion: 
(a) Intensive cropping 
(b) Reforestation 
(c) Terrace farming 
OR 
Nutrient cycling in the ecosystem involves the following three aspects: 
(a) Input of nutrients 
(b) Output of nutrients 
(c) Internal nutrient cycling 
 
4. When a car is moving from rest, its initial velocity (u) is zero. 
The distance travelled (s) by this car can be found by using the second equation of 
motion. 
? ? ?
2
2
2
u = 0 m/s
a = 3 m/s
t = 9 min = 540 s
To find the distance we use
1
s = ut+ at
2
1
 s (0).540 (3).(540)
2
s = 437400 m = 437.4 km.
 
Therefore, the distance travelled by this car is 437.4 km. 
Calculating the speed of this car, 
Distance 437400
Speed =  =  = 810 m/s
time 540
 
The speed of this car is 810 m/s. 
  
 
CBSE IX | SCIENCE 
 Sample Paper – 4 Solution 
 
     
5. Evaporation is a phenomenon of change of a liquid into vapour at any temperature 
below its boiling point. 
When evaporation occurs, the particles of the liquid absorb heat from the surrounding 
to regain the energy lost during evaporation. This absorption of energy from the 
surrounding makes the surrounding cool. 
 
Section C 
 
6. Drawbacks of Rutherford’s Model of an Atom: 
? Rutherford’s atomic model could not explain how moving electrons remain in their 
orbits. 
? Any charged particle during acceleration would radiate energy, and while revolving, 
it would lose its energy and eventually fall into the nucleus. 
? This means that the atom would be highly unstable. 
? But, matter is composed of stable atoms. 
? So, the major drawback of Rutherford’s atomic model was that it could not explain 
the stability of atoms. 
 
7.  
(a) Desirable characteristics can be incorporated into crop varieties by the following 
methods: 
? Hybridisation: Selected plants with one or more desirable traits are crossed with 
one another.  
? Genetic engineering: Desirable characteristics are introduced into selected 
plants with the help of techniques of biotechnology. 
(b) Crops are selected for intercropping based on different nutrient requirements and 
different sowing and harvesting patterns of crops, e.g. soybean and maize. 
OR 
Effects due to excessive irrigation of crops: 
? Soil erosion 
? Changes in the composition of soil due to solubilisation of some of the minerals 
from the soil 
? Water pollution 
  
 
CBSE IX | SCIENCE 
 Sample Paper – 4 Solution 
 
     
8.  
(a)When acetone is poured on the palm, it takes up the latent heat of vaporisation 
required to change from the liquid state to vapour state from our hand. The hand 
loses heat and gets cooled. 
(b)The earthen pot has small pores in its walls. Some of the water continuously seeps 
out from these pores. This water evaporates and absorbs heat of vaporisation from 
the remaining water. Thus, the remaining water loses heat and gets cooled. 
(c) Larger the surface area, faster will be the cooling. Evaporation is a surface 
phenomenon. The particles of tea on the surface absorb the heat for vaporisation 
from the remaining particles of the tea and evaporate. The tea thus loses heat and 
cools faster. 
 
9. Distance travelled by the pulse ‘s’ = 8 m 
Time taken ‘t’ = 0.05 s 
Frequency ‘ ?’ = 200 Hz 
(a) We know that 
 
distance s 8
v =  =  =  = 160 m/s
time t 0.05
 
Hence, the velocity of the pulse is 160 m/s. 
 
(b) We know that 
 
v = ??
v 160
? =  =  = 0.8 m
? 200
 
Hence, the wavelength of the pulse is 0.8 m. 
 
10. Force (F) acting between the Earth (mass M) and the stone of mass (m) separated by 
the distance (r) by the universal law of gravitation is given by the equation      
?
2
M.m
F = G
r
. 
The mass of stone is negligible (too less) when compared to the mass of the Earth which 
is 6 ? 10
24
 kg. Thus, the stone falls on the Earth and the Earth does not rise towards the Sun.  
 
  
  
 
CBSE IX | SCIENCE 
 Sample Paper – 4 Solution 
 
     
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 10 10 100 N
 
 
?
?
? ? ? ?
? ? ?
22
2
Force (F)
Pressure (P) =
Area (A)
Area of the surface of the cuboid (A)= b
Assuming the surface of 50 20 cm to be in contact with the floor.
A 50 20 1000 cm 0.1 m
100
P 1000 N/m
0.1
 
Pressure exerted by the block on the floor is 1000 N/m
2
. 
 
?
? ? ? ?
? ? ?
22
2
Assuming the surface of 50 20 cm to be in contact with the floor.
A 100 50 15000 cm 1.5 m
100
P 66.6 N/m
1.5
 
Pressure exerted by the block on the floor is 66.6 N/m
2
. 
OR 
Work is said to be 1 joule when a force of 1 Newton acting on an object displaces it 
through 1 metre in the direction of the force. 
Relation between joule and erg is 
5
52
77
7
1 J = 1 N × 1 m
Now, 1 N = 10 dyne
1 J = 10 dyne × 10 cm
1 J = 10 dyne × cm = 10 erg
1 J = 10 erg
 
 
12.  1 mole of sulphur dioxide, SO2 = Mass of S + Mass of 2 'O' 
                                              = 32 + 2 × 16 
                                               = 64 grams 
Now, 64 g of sulphur dioxide = 1 mole 
 
Page 5


  
 
CBSE IX | SCIENCE 
 Sample Paper – 4 Solution 
 
     
CBSE 
Class IX Science 
Sample Paper – 4 Solution  
                                                                                                                           
Section A 
 
1. The practice of growing different types of crops alternately in the same field in pre-
planned succession is called crop rotation.  
 
2. Conversion of inert elemental nitrogen gas into its biologically usable form is called 
nitrogen fixation. 
 
Section B 
 
3. Measures to prevent soil erosion: 
(a) Intensive cropping 
(b) Reforestation 
(c) Terrace farming 
OR 
Nutrient cycling in the ecosystem involves the following three aspects: 
(a) Input of nutrients 
(b) Output of nutrients 
(c) Internal nutrient cycling 
 
4. When a car is moving from rest, its initial velocity (u) is zero. 
The distance travelled (s) by this car can be found by using the second equation of 
motion. 
? ? ?
2
2
2
u = 0 m/s
a = 3 m/s
t = 9 min = 540 s
To find the distance we use
1
s = ut+ at
2
1
 s (0).540 (3).(540)
2
s = 437400 m = 437.4 km.
 
Therefore, the distance travelled by this car is 437.4 km. 
Calculating the speed of this car, 
Distance 437400
Speed =  =  = 810 m/s
time 540
 
The speed of this car is 810 m/s. 
  
 
CBSE IX | SCIENCE 
 Sample Paper – 4 Solution 
 
     
5. Evaporation is a phenomenon of change of a liquid into vapour at any temperature 
below its boiling point. 
When evaporation occurs, the particles of the liquid absorb heat from the surrounding 
to regain the energy lost during evaporation. This absorption of energy from the 
surrounding makes the surrounding cool. 
 
Section C 
 
6. Drawbacks of Rutherford’s Model of an Atom: 
? Rutherford’s atomic model could not explain how moving electrons remain in their 
orbits. 
? Any charged particle during acceleration would radiate energy, and while revolving, 
it would lose its energy and eventually fall into the nucleus. 
? This means that the atom would be highly unstable. 
? But, matter is composed of stable atoms. 
? So, the major drawback of Rutherford’s atomic model was that it could not explain 
the stability of atoms. 
 
7.  
(a) Desirable characteristics can be incorporated into crop varieties by the following 
methods: 
? Hybridisation: Selected plants with one or more desirable traits are crossed with 
one another.  
? Genetic engineering: Desirable characteristics are introduced into selected 
plants with the help of techniques of biotechnology. 
(b) Crops are selected for intercropping based on different nutrient requirements and 
different sowing and harvesting patterns of crops, e.g. soybean and maize. 
OR 
Effects due to excessive irrigation of crops: 
? Soil erosion 
? Changes in the composition of soil due to solubilisation of some of the minerals 
from the soil 
? Water pollution 
  
 
CBSE IX | SCIENCE 
 Sample Paper – 4 Solution 
 
     
8.  
(a)When acetone is poured on the palm, it takes up the latent heat of vaporisation 
required to change from the liquid state to vapour state from our hand. The hand 
loses heat and gets cooled. 
(b)The earthen pot has small pores in its walls. Some of the water continuously seeps 
out from these pores. This water evaporates and absorbs heat of vaporisation from 
the remaining water. Thus, the remaining water loses heat and gets cooled. 
(c) Larger the surface area, faster will be the cooling. Evaporation is a surface 
phenomenon. The particles of tea on the surface absorb the heat for vaporisation 
from the remaining particles of the tea and evaporate. The tea thus loses heat and 
cools faster. 
 
9. Distance travelled by the pulse ‘s’ = 8 m 
Time taken ‘t’ = 0.05 s 
Frequency ‘ ?’ = 200 Hz 
(a) We know that 
 
distance s 8
v =  =  =  = 160 m/s
time t 0.05
 
Hence, the velocity of the pulse is 160 m/s. 
 
(b) We know that 
 
v = ??
v 160
? =  =  = 0.8 m
? 200
 
Hence, the wavelength of the pulse is 0.8 m. 
 
10. Force (F) acting between the Earth (mass M) and the stone of mass (m) separated by 
the distance (r) by the universal law of gravitation is given by the equation      
?
2
M.m
F = G
r
. 
The mass of stone is negligible (too less) when compared to the mass of the Earth which 
is 6 ? 10
24
 kg. Thus, the stone falls on the Earth and the Earth does not rise towards the Sun.  
 
  
  
 
CBSE IX | SCIENCE 
 Sample Paper – 4 Solution 
 
     
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 10 10 100 N
 
 
?
?
? ? ? ?
? ? ?
22
2
Force (F)
Pressure (P) =
Area (A)
Area of the surface of the cuboid (A)= b
Assuming the surface of 50 20 cm to be in contact with the floor.
A 50 20 1000 cm 0.1 m
100
P 1000 N/m
0.1
 
Pressure exerted by the block on the floor is 1000 N/m
2
. 
 
?
? ? ? ?
? ? ?
22
2
Assuming the surface of 50 20 cm to be in contact with the floor.
A 100 50 15000 cm 1.5 m
100
P 66.6 N/m
1.5
 
Pressure exerted by the block on the floor is 66.6 N/m
2
. 
OR 
Work is said to be 1 joule when a force of 1 Newton acting on an object displaces it 
through 1 metre in the direction of the force. 
Relation between joule and erg is 
5
52
77
7
1 J = 1 N × 1 m
Now, 1 N = 10 dyne
1 J = 10 dyne × 10 cm
1 J = 10 dyne × cm = 10 erg
1 J = 10 erg
 
 
12.  1 mole of sulphur dioxide, SO2 = Mass of S + Mass of 2 'O' 
                                              = 32 + 2 × 16 
                                               = 64 grams 
Now, 64 g of sulphur dioxide = 1 mole 
 
  
 
CBSE IX | SCIENCE 
 Sample Paper – 4 Solution 
 
     
1/4 mole of sulphur dioxide will have the same number of molecules as 1/4 mole of 
oxygen. So, we convert 1/4 mole of oxygen into mass in grams. 
1 mole of oxygen, O2 = Mass of 2 'O' atoms 
                             = 2 × 16 
                           = 32 grams 
Now, 1 mole of oxygen = 32 grams 
 
Thus, 8 grams of oxygen will contain the same number of molecules as 16 grams of 
sulphur dioxide. 
OR 
 
(a)  
Calcium nitride 
  
(b)    
Calcium hydroxide 
 
 
(c)   
Sodium carbonate 
 
 
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