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 carbonateRead More

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