This section includes 7 InterviewSolutions, each offering curated multiple-choice questions to sharpen your Current Affairs knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
Complete the ionization equation of phosphoric acid (H3PO4).H3PO4 → ………… + PO43- (Phosphate ion) |
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Answer» H3PO4 → 3H+ + PO43- (Phosphate ion) |
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| 2. |
Compute the mass of one molecule and the molecular mass of C6H6 (benzene). (At. mass of C = 12, H = 1 u). |
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Answer» Molecular weight of C6H6 = 6 × 12 + 6 × 1 = 78 g, Mass of 1 molecule = 78/6.002 x 1023 = 12.94 × 10-23 g = 1.294 × 10-22 g |
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| 3. |
Which property of an element is always a whole number?(A) Atomic weight (B) Atomic volume (C) Atomic number (D) All of these |
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Answer» Correct option: (C) Atomic number |
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| 4. |
Boron has two stable isotopes, 10B (19%) and 11B (81%). The atomic mass that should appear for boron in the periodic table is ______.(A) 10.0 (B) 10.2 (C) 10.8 (D) 11.2 |
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Answer» Correct option: (C) 10.8 Atomic mass = \(\cfrac{10\times 19 + 81 \times11}{100}\) = \(\cfrac{1081}{100}\) = 10.81 |
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| 5. |
The weight of a molecule of the compound C60H122 is _______.(A) 1.4 x 10-21 g (B) 1.09 x 10-21 g (C) 5.025 x 1023 g (D) 16.023 x 1023 g |
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Answer» Correct option: (A) 1.4 x 10-21 g Molecular weight of C60H122 = 12 x 60 + 122 x 1 = 720 + 122 = 842 ∵ 6 x 1023 molecules = 842 g 1 molecule = \(\cfrac{842}{6\,\times 10^{23}}\) = 140.33 x 10-23 = 1.4 x 10-21 g |
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| 6. |
The gram molecule of benzene is equal to _______ g C6H6. (A) 70 (B) 72 (C) 10 (D) 78 |
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Answer» Correct option: (D) 78 Molecular formula of benzene is C6H6. ∴ Molecular mass = sum of atomic weight of all the atoms ∴ Molecular mass = 12 x 6 + 6 x 1 = 72 + 6 = 78 ∴ According to Avogadro’s law, the gram molecule of benzene is equal to 78 g of C6H6. |
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| 7. |
Number of significant digit in 20.00 ….. (a) 1 (b) 2 (c) 3 (d) 4 |
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Answer» Correct answer is (d) 4 |
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| 8. |
Which of the following measurements is most precise? (a) 4.00 mm (b) 4.00 cm (c) 4.00 m (d) 4.00 km |
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Answer» Correct answer is (a) 4.00 mm |
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| 9. |
The mean radius of a wire is 2 mm. Which of the following measurements is most accurate? (a) 1.9 mm (b) 2.25 mm(c) 2.3 mm (d) 1.83 mm |
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Answer» Correct answer is (a) 1.9 mm |
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| 10. |
If displacement of a body s = (200 ± 5) m and time taken by it t = (20 + 0.2) s, then find the percentage error in the calculation of velocity. |
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Answer» percentage error in measurement of displacement = \(\frac{5}{200}\)x100 Percentage error in measurement of time = \(\frac{0.2}{20}\) x 100 ∴ Maximum permissible error = 2.5 + 1 = 3.5% |
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| 11. |
Dimensions [M L-1 T-1] are related to …… (a) torque (b) work (c) energy (d) Coefficient of viscosity |
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Answer» (d) Coefficient of viscosity |
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| 12. |
If error in measurement of radius of sphere is 1%. What will be the error in measurement of volume? (a) 1% (b) % (c) 3% (d) 10% |
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Answer» Correct answer is (c) 3% |
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| 13. |
Which of the following pairs does not have same dimension?(a) Moment of inertia and moment of force (b) Work and torque(c) Impulse and momentum (d) Angular momentum and Plank’s constant |
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Answer» (a) Moment of inertia and moment of force |
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| 14. |
Dimensions of impulse are …..(a) [ml2T-1](b) [MLT-2](c) [MLT-1](d) [ML2T0] |
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Answer» Correct answer is (c) [MLT-1] |
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| 15. |
What is meant by pressure energy? |
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Answer» The energy possessed by a liquid by virtue of its pressure is called pressure energy. |
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| 16. |
Why are sleepers used below the rails? |
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Answer» By placing sleepers below the rails cross-sectional area is increased. This in turn reduces the pressure due to weight of the train on the rails as pressure is defined as the force per unit area. |
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| 17. |
What is indicated by sudden decrease in atmospheric pressure? |
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Answer» Sudden decrease in atmospheric pressure indicates the occurrence of storm. |
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| 18. |
Write down S.I. units of torque and angular velocity. |
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Answer» Newton-metre and radiam/s respectively. |
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| 19. |
A car moving along a straight high-way with a speed of 35 m/s is brought to stop within a distance of 200 m. What Is the retardation, and how long does it take for the car to stop? |
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Answer» Initial speed of the car, u = 35 ms-1 Final speed of the car, v = 0 Let a be the retardation of the car. Then using the relation, v2 = u2 + 2as, we have 0 = (35)2 + 2a × 200 a = – (35 x 35)/(2 x 200) = – 3.06 ms-2 Let t be the time taken by the car to come to stop. Then, v = u + at ; 0 = 35 – 3.06 × t or t = 35/3.06 = 11.43 s. |
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| 20. |
A car starts from rest and accelerates from rest uniformly for 10 s to a velocity of 36 kmhr-1. It then runs at a constant velocity and is finally brought to rest in 50 m with uniform retardation. If the total distance covered by the car is 500 m, find1. acceleration and2. retardation. |
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Answer» 1. Initial velocity of the car u = 0; Final velocity v = 36 kmhr-1 = (36 x 1000)/3600 = ms-1 = 10 ms-1 time taken t = 10 s ∴ acceleration a = (v - u)/t = (10 - 0)/10 = 1ms-2 2. To find the retardation During the motion with retardation, Initial velocity of the car u = 10 ms-1 Final velocity v = 0, distance travelled, s = 50 m Using the relation v2 = u2 + 2as, 0 = 102 – 2a × 50 a = (-100/(2 x 50)) = -1 ms-2 |
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| 21. |
Class 10 Maths MCQ Questions of Surface Areas and Volumes with Answers? |
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Answer» Class 10 Maths MCQ Questions of Surface areas and volumes with Answers is recommended for the students. Students attempt to solve these questions first and afterward check with the appropriate answer. This practice will assist to gain problem-solving abilities and build their confidence level. Students are encouraged to solve the MCQ Questions of Surface areas and volumes to know various ideas. Practicing the MCQ question for Class 1O Maths of Surface areas and volumes with answers will support your confidence subsequently assisting you with scoring great in the exam. Solve the underneath given Class 10 Maths MCQ Questions of Surface areas and volumes with Answers and check your answers with the detailed answers here. Practice Class 10 MCQ Questions for Maths 1. During conversion of a solid from one shape to another, the volume of the new shape will (a) increase 2. A right circular cylinder of radius r cm and height h cm (h>2r) just encloses a sphere of diameter (a) r cm 3. If two solid hemispheres of same base radii r, are joined together along their bases, then curved surface area of this new solid is (a) 4πr2 4. The shape of an ice-cream cone is a combination of: (a) Sphere + cylinder 5. If a cone is cut parallel to the base of it by a plane in two parts, then the shape of the top of the cone will be a: (a) Sphere 6. A cylindrical pencil sharpened at one edge is combination of: (a) a cone and a cylinder 7. A shuttle cock used for playing badminton has the shape of a combination of: (а) a cylinder and a sphere 8. The radius of a wire is decreased to one third. If volume remains the same, the length will become: (a) 3 times 9. A cylinder and a cone area of same base radius and of same height. The ratio of the volume of cylinder to that of cone is: (a) 3 : 1 10. If the surface areas of two spheres are in ratio 16 : 9, then their volumes will be in the ratio: (a) 27 : 64 11. A solid cylinder of radius r and height h is placed over other cylinder of same height and radius. The total surface area of the shape so formed is (a) 4πrh + 4πr2 12. The radii of the top and bottom of a bucket of slant height 45cm are 28cm and 7 cm respectively. The curved surface area of the bucket is: (a) 4950 cm2 13. If we cut a cone in two parts by a plane parallel to the base, then the bottom part left over is the: (a) Cone 14. If r is the radius of the sphere, then the surface area of the sphere is given by; (a) 4 π r2 15. If we change the shape of an object from a sphere to a cylinder, then the volume of cylinder will (a) Increase 16. The radius of the top and bottom of a bucket of slant height 35 cm are 25 cm and 8 cm. The curved surface of the bucket is: (a) 4000 sq.cm 17. The total surface area of a hemispherical solid having radius 7 cm is (a) 462 cm2 18. A solid formed on revolving a right angled triangle about its height is (a) cylinder 19. If we join two hemispheres of same radius along their bases, then we get a; (a) Cone 20. Two identical solid hemispheres of equal base radius r cm are stuck together along their bases. The total surface area of the combination is (a) 6πr2 Answer: 1. Answer: (c) remain unaltered Explanation: During conversion of one solid shape to another, the volume of the new shape will remain unaltered. 2. Answer: (b) 2r cm Explanation: Because the sphere is enclosed inside the cylinder, therefore the diameter of sphere is equal to the diameter of cylinder which is 2r cm. 3. Answer: (a) 4πr2 Explanation: Because curved surface area of a hemisphere is and here we join two solid hemispheres along their bases of radii r, from which we get a solid sphere. Hence the curved surface area of new solid = 2πr2 + 2πr2 = 4πr2 4. Answer: (d) Hemisphere + cone Explanation: The shape of an ice-cream cone is a combination of a hemisphere and a cone. 5. Answer: (c) Cone itself Explanation: If we cut a cone into two parts parallel to the base, then the shape of the upper part remains the same. 6. Answer: (a) a cone and a cylinder 7. Answer: (d) a frustum of a cone and a hemisphere 8. Answer: (c) 9 times 9. Answer: (a) 3 : 1 10. Answer: (b) 64 : 27 11. Answer: (c) 4πrh + 2πr2 Explanation: Since the total surface area of cylinder of radius r and height h = 2πrh + 2πr2. When one cylinder is placed over the other cylinder of same height and radius, Then height of new cylinder = 2h And radius of the new cylinder = r Therefore total surface area of new cylinder = 2πr (2h) + 2πr2 = 4πrh + 2πr2 12. Answer: (a) 4950 cm2 Explanation: Curved Surface area of the bucket = π (R + r) l ⇒ Curved surface area of the bucket = π (28 + 7) X 45 ⇒ Curved surface area of the bucket = 4950 cm2 13. Answer: (b) Frustum of cone 14. Answer: (a) 4 π r2 Explanation: If r is the radius of the sphere, then the surface area of the sphere is given by 4 π r2. 15. Answer: (c) Remains unchanged Explanation: If we change the shape of a three-dimensional object, the volume of the new shape will be same. 16. Answer: (c) 3630 sq.cm Explanation: Curved surface of bucket = π(R1 + R2) x slant height (l) Curved Surface = (22/7) x (25 + 8) x 35 CSA = 22 x 33 x 5 = 3630 sq.cm. 17. Answer: (a) 462 cm2 = 3 × 22/7 × 7 × 7 = 462 cm2 18. Answer: (c) right circular cone 19. Answer: (c) Sphere Explanation: If we join two hemispheres of same radius along their bases, then we get a Sphere. 20. Answer: (c) 4πr2 Explanation: When two hemispheres are joined together along their bases, a sphere of the same base radius is formed. Curved Surface Area of a sphere = 4πr2 Click here for practice more MCQ questions from Chapter Surface Areas and Volumes Class 10 Maths |
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| 22. |
Class 9 Maths MCQ Questions of Surface Areas and Volumes with Answers? |
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Answer» Sarthaks eConnect is a portal that gives MCQ Questions with Answers and other examination materials for students. It assists you with revise the total Syllabus and score more marks in your exams. The Class 9 MCQ Questions of Surface Areas and Volumes with Answer will teach students about the connection between the length and expansiveness concerning various shapes and the incorporation of stature any place it is required. Practice MCQ Questions for Class 9 Maths 1. In a cylinder, radius is doubled and height is halved, curved surface area will be (a) halved 2. During conversion of a solid from one shape to another, the volume of the new shape will (A) increase 3. The radii of two cylinders are in the ratio of 2:3 and their heights are in the ratio of 5:3. The ratio of their volumes is: (a) 10: 17 4. The total surface area of a cone whose radius is r/2 and slant height 2l is (a) 2πr(l+r) 5. The lateral surface area of a cube is 256 m2. The volume of the cube is (a) 512 m3 6. A cuboid having surface areas of 3 adjacent faces as a, b and c has the volume: (a) 3\(\sqrt{abc}\) 7. The number of planks of dimensions (4 m × 50 cm × 20 cm) that can be stored in a pit that is 16 m long, 12m wide and 4 m deep is (a) 1900 8. A cone is 8.4 cm high and the radius of its base is 2.1 cm. It is melted and recast into a sphere. The radius of the sphere is (a) 4.2 cm 9. The length of the longest pole that can be put in a room of dimensions (10 m × 10 m × 5m) is (a) 15m 10. The total surface area of a cube is 96 cm2. The volume of the cube is: (a) 8 cm3 11. Volume of spherical shell is (a) 2/3 πr3 12. Volume of hollow cylinder (a) π(R2 – r2)h 13. The radius of a sphere is 2r, then its volume will be (a) 4/3 πr3 14. The radius of a hemispherical balloon increases from 6 cm to 12 cm as air is being pumped into it. The ratio of the surface areas of the balloon in the two cases is (a) 1:4 15. The surface area of a sphere of radius 14 cm is: (a) 1386 sq.cm 16. If slant height of the cone is 21cm and the diameter of the base is 24 cm. The total surface area of a cone is: (a) 1200.77 sq.cm 17. The diameter of the base of a cone is 10.5 cm, and its slant height is 10 cm. The curved surface area is: (a) 150 sq.cm 18. The Curved surface area of a right circular cylinder is 4.4 sq.cm. The radius of the base is 0.7 cm. The height of the cylinder will be: (a) 2 cm 19. The curved surface area of a right circular cylinder of height 14 cm is 88 cm2. The diameter of the base is: (a) 2 cm 20. The radius of a hemispherical balloon increases from 6 cm to 12 cm as air is being pumped into it. The ratios of the surface areas of the balloon in the two cases is (a) 1 : 4 Answer: 1. Answer: (c) same 2. Answer: (C) remain unaltered Explanation: During conversion of one solid shape to another, the volume of the new shape will remain unaltered. 3. Answer: (b) 20: 27 Explanation: Given that, the radii of two cylinders are in the ratio of 2:3 Hence, r1= 2r, r2 = 3r Also, given that, the height of two cylinders are in the ratio 5:3. Hence, h1 = 5h, h2 = 3h The ratio of the volume of two cylinders = V1/V2 = πr12h1/πr22h2 = [(2r)2(5h)]/[(3r)2(3h)] Ratio of their volumes =(20r2h)/(27r2h) = 20/27 = 20: 27. 4. Answer: (b) πr(l+(r/4)) Explanation: The total surface area of cone = πr(l+r) square units. If r = r/2 and l= 2l, then the TSA of cone becomes, TSA of cone = π(r/2)[(2l+(2/r)] =π[(rl)+(r2/4)] TSA of new cone =πr[l+(r/4)] 5. Answer: (a) 512 m3 Explanation: The lateral surface area of cube = 4a2 4a2= 256 a2 = 256/4 =64 a = 8 m Hence, the volume of cube = a3 cube units V = 83 = 512 m3. 6. Answer: (b) \(\sqrt{abc}\) 7. Answer: (b) 1920 Explanation: Volume of Plank = 400 cm×50cm×20cm=400000cm3 Volume of pits = 1600cm×1200cm×400cm = 768000000cm3 Number of planks = Volume of planks/Volume of pits = 768000000/400000 Hence, the number of pits = 1920 8. Answer: (b) 2.1 cm Explanation: Given that the height of cone = 8.4 cm Radius of cone = 2.1 cm Also, given that the volume of cone = volume of a sphere (1/3)πr2h = (4/3)πr3 (1/3)π(2.1)2(8.4) = (4/3)πr3 37.044= 4r3 r3= 37.044/4 r3= 9.261 r = 2.1 Therefore, the radius of the sphere is 2.1 cm. 9. Answer: (a) 15m Explanation: Given: l=10m, b= 10m, h= 5m The length of the longest pole = √[102+102+52] = √(100+100+25) = √225 = 15 m. 10. Answer: (c) 64 cm3 Explanation: We know that the TSA of the cone = 6a2. 6a2 = 96 cm2 a2 = 96/6 = 16 a =4 cm The volume of cone = a3 cubic units V = 43 = 64cm3. 11. Answer: (c) 4/3 π(R3 – r3) 12. Answer: (a) π(R2 – r2)h 13. Answer: (d) 32/3 πr3 14. Answer: (a) 1:4 Explanation: We know that the total surface area of the hemisphere = 3πr2 square units. If r= 6cm, then TSA = 3π(6)2 = 108π If r = 12 cm, then TSA = 3π(12)2= 432π Then the ratio = (108π)/(432π) Ratio = 1/4, which is equal to 1:4. 15. Answer: (c) 2464 sq.cm Explanation: Radius of sphere, r = 14 cm Surface area = 4πr2 = 4 x 22/7 x (14)2 = 2464 sq.cm. 16. Answer: (d) 1244.57 sq.cm Explanation: Total surface area = πr(l + r) r = 24/2 = 12 cm l = 21 cm TSA = π(12)(21 + 12) = 1244.57 sq.cm 17. Answer: (b) 165 sq.cm Explanation: Diameter = 10.5, Radius = 10.5/2 Slant height, l = 10cm Curved surface area of cone = πrl = π(5.25)(10) CSA = 165 sq.cm 18. Answer: (c) 1 cm Explanation: Curved surface area of cylinder = 2πrh 2πrh = 4.4 h = 4.4/(2π x 0.7) h = 1 cm 19. Answer: (a) 2 cm Explanation: Curved surface area of cylinder = 88 sq.cm Height = 14 cm 2πrh = 88 r = 88/2πh r=1 cm Diameter = 2r = 2cm 20. Answer: (a) 1 : 4 Click here to practice: – Surface Areas and Volumes MCQ Question for Class 9 Maths |
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| 23. |
Distinguish between: Speed and velocity. |
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| 24. |
A cone of height 7 cm and base radius 1 cm is carved from a cuboidal block of wood 10 cm × 5 cm × 2 cm. Assuming π = \(\frac{22}{7}\). What is the percentage of wood wasted in the process ?(a) \(92\frac23\)% (b) \(46\frac13\)%(c) \(53\frac23\)%(d) \(7\frac13\)% |
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Answer» (a) \(92\frac23\)% Volume of cone = \(\frac13\)πr2h = \(\frac13\times\frac{22}{7}\times1\times7=\frac{22}{3}\) cu. cm Volume of cubical block = (10 × 5 × 2) cm3 = 100 cm3 ∴ Wastage of wood = \(\frac{\big(100-\frac{22}{7}\big)}{100}\times100\) = \(\frac{278}{3}\)% = \(92\frac23\)% |
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| 25. |
Distinguish between: Balanced force and unbalanced force. |
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| 26. |
Distinguish between:Balanced force and Unbalanced force |
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| 27. |
write the geographical conditions for wheat, rice, jute, cotton and tea and explain the role of organisms in these crops. |
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Answer» 1) Rice: It is a kharif crop which requires high temperature and high humidity with annual rainfall above 100 cm. 2) Wheat: It requires a cool growing season and a bright sunshine at the time of ripening.it requires 50 to 75 cm of annual rainfall evenly distributed over the growing season. 3) Sugar cane: It is a tropical as well as sub tropical crop .it grows well in hot and humid climate with a temperature of 21 to 27 degrees and an annual rainfall between 75 to 100 cm. 4) Cotton: It grows well on black soil.it requires high temperature,light rainfall or irrigation,210 frost free days for its growth.it is a kharif crop and requires 6 to 8 months to mature. 5) Jute: It is also known as golden fibre. grows well on well-drained fertile soils in the flood plains where soils are renewed every year.high temperature is required. 6) Tea: It grows well in tropical and sub-tropical climates endowed with deep and fertile well-drained soil,rich in humus and organic matter.tea bushes require warm and moist frost free climate all through the year. |
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| 28. |
Write notes on the following:The Battle of Bhopal |
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Answer» The emperor became restless due to Bajirao’s attack. He called the Nizam to protect Delhi. The Nizam attacked Bajirao with his large army. Bajirao defeated him at Bhopal. The Nizam agreed to secure the sanad of Malwa subhedari to Marathas from the Badshah. |
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| 29. |
Radika is going from her residence to her office in an autorickshaw. Is she doing some work? Give reason. According to scientific definition of work. |
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Answer» Yes, she does work because for work to be done there has to be some displacement. The object has to be shifted from its original position. Now in case, the situation was Radhika went from home to office and back home in that autorickshaw the work done would have been zero because she is returning to her original place and there is no shift.
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| 30. |
What were the great qualities of Bajirao? |
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Answer» Bajirao was a great warrior, a powerful ruler who established the Maratha dominance in North. |
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| 31. |
Where did Bajirao defeat the Nizam? |
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Answer» Bajirao defeated the Nizam at Palkhed near Aurangabad. |
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| 32. |
A bullet of mass 'm' is fired with a velocity 'v' into a block of mass M. What is the final velocity of the system? |
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Answer» vector v = -{vector(mv)}/{M + m} |
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| 33. |
One end of a string of length L is connected to a particle of mass m and the other to a small peg on a smooth horizontal table. If the particle moves in a circle with speed v the net force on the particle (directed towards the centre) is:1. T.2. T –\(\frac{mv^2}{L}\)3. T + \(\frac{mv^2}{L}\)4. 0 T is the tension in the string. [Choose the correct alternative]. |
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Answer» 1. The centripetal force necessary for the particle to move in a circular path is provided by the tension in the string. Hence net force on the particle is nothing but tension T in the string. |
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| 34. |
State whether the following statements are true or false:The direction of acceleration can be opposite to that of velocity. |
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Answer» The direction of acceleration can be opposite to that of velocity.- True |
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| 35. |
One end of a string of length l is connected to a particle of mass m and the other to a small peg on a smooth horizontal table. If the particle moves in a circle with speed v, the net force on the particle (directed towards the centre) is:(i) T, (ii) T - mv2/l, (iii) T + mv2/l, (iv) 0Here T is the tension in the string (choose the correct alternative.) |
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Answer» (i) is correct. The particle moving along the circular path is constantly accelerated and hence it must be under the action of an external force. The net force on the particle is T. |
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| 36. |
What is.the action and reaction in the following cases?(a) A person swimming in the water.(b) A horse pulling the cart |
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Answer» (a) Action: Backward push on the water Reaction: Forward push (by water) on the man. (b) Action: Pull on the cart. Reaction: Backward tension in the rope. |
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| 37. |
State whether the following statements are true or false:Work is a vector quantity. |
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Answer» Work is a vector quantity.- False |
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| 38. |
Give the magnitude and direction of the net force acting on a) a drop of rain falling down with a constant speed, b) a cork of mass 10 g floating on water, c) a kite skilfully held stationary in the sky, d) a car moving with a constant velocity of 30 km/h on a rough road, e) a high-speed electron in space far from all material objects, and free of electric and magnetic fields. |
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Answer» a) Zero net force. The rain drop is falling with a constant speed. Hence, it acceleration is zero. As per Newton’s second law of motion, the net force acting on the rain drop is zero. b) Zero net force The weight of the cork is acting downward. It is balanced by the buoyant force exerted by the water in the upward direction. Hence, no net force is acting on the floating cork. c) Zero net force The kite is stationary in the sky, i.e., it is not moving at all. Hence, as per Newton’s first law of motion, no net force is acting on the kite. d) Zero net force The car is moving on a rough road with a constant velocity. Hence, its acceleration is zero. As per Newton’s second law of motion, no net force is acting on the car. e) Zero net force The high speed electron is free from the influence of all fields. Hence, no net force is acting on the electron. |
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| 39. |
Give the magnitude and direction of the net force acting on the drop of rain falling down with a constant speed. |
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Answer» As the drop of rain is falling down with a constant speed, in accordance with first law of motion, the net force on the drop of rain is zero. |
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| 40. |
Give the magnitude and direction of the net force acting on (a) A drop of rain falling down with constant speed. (b) A kite skillfully held stationary in the sky. |
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Answer» (1) According to first law of motion F = 0 as a = 0 (particle moves with constant speed) (2) Since kite is stationary net force on the kite is also zero. |
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| 41. |
State whether the following statements are true or false:Displacement is always greater than distance. |
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Answer» Displacement is always greater than distance.- False |
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| 42. |
A constant retarding force of 50 N is applied to a body of mass 20 kg moving initially with a speed of 15 ms-1. How long does the body take to stop? |
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Answer» Here, M = 20 kg, F = 50 (retarding force) As F = mg ⇒ a = F/m = -50/20 = -2.5 ms-2 Also, v = u + at, Here u = 15 ms-1, v = 0 ⇒ 0 = 15 + (-2.5) x t ⇒ t = 6s |
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| 43. |
A constant force acting on a body of mass 3.0 kg changes its speed from 2.0 ms-1 to 3.5 ms-1 in 25 s. The direction of the motion of the body remains unchanged. What is the magnitude and direction of the force? |
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Answer» Here, u = 2 ms-1, v = 3.5 ms-1, t = 25 s From v = u + at ⇒ 3.5 = 2 + a x 25 ⇒ a = {3.5 - 2}/{25} = 0.06 ms-2 Mass of the body = m = 3 kg Force acting on the body F = ma = 3 x 0.06 = 0.18 N Since the applied force increases the speed of the body, it acts in the direction of the motion. |
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| 44. |
State whether the following statements are true or false:The distance and displacement are equal only if, motion is along a straight path. |
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Answer» The distance and displacement are equal only if, motion is along a straight path.- True |
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| 45. |
Name the following:(1) The scientist who summarized motion in a set of equations of motion.(2) Motion of an object along a circular path with uniform speed.(3) What is the backward motion of the gun called?(4) The motion in which the object covers equal distance in equal intervals of time.(5) S. I. unit of acceleration.(6) CGS unit of momentum |
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Answer» (1) Isaac Newton (2) Uniform circular motion (3) Recoil (4) Uniform motion (5) m/s2 (6) g cm/s |
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| 46. |
State whether the following statements are true or false:(1) If an object experiences acceleration, a force is acting on it.(2) A train pulling out from a station is in uniform motion.(3) If a bus in motion is suddenly stopped, the passengers fall backwards.(4) If a single force is acting on an object, it will always accelerate.(5) In circular motion, direction of motion is tangential.(6) The inertia of a body is measured in terms of its mass. |
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Answer» (1) True (2) False (3) False (4) True (5) True (6) True |
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| 47. |
A metre scale is moving with uniform velocity. This implies (a) the force acting on the scale is zero, but a torque about the centre of mass can act on the scale. (b) the force acting on the scale is zero and the torque acting about centre of mass of the scale is also zero.(c) the total force acting on it need not be zero but the torque on it is zero.(d) neither the force nor the torque need to be zero. |
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Answer» (b) the force acting on the scale is zero and the torque acting about centre of mass of the scale is also zero. |
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| 48. |
What is error? |
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Answer» The difference in the true value and the measured value of a quantity is called error of measurement. |
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| 49. |
What is precision? |
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Answer» Precision is a measure of how consistently a device records nearly identical values i.e., reproducible results. |
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| 50. |
A mass 2m moving with some speed is directly approaching another mass m moving with double speed. After some time, they collide with coefficient of restitution 0.5. Ratio of their respective speeds after collision is (A) 2/3 (B) 3/2 (C) 2 (D) 1/2 |
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Answer» Correct answer is (B) 3/2 |
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