Problem Set Geas

PROBLEM SET 2 1. The position of a particle moving along the x-axis is given by x(t) = t2 - t + 8, where x is in units of meters, and t is in seconds. Find the velocity of the particle when t = 5s. a. 9.0m/s b. 10.0m/s c. 11.0m/s d. 12.0m/s 2. If a particle's position is given by the expression x(t) = 3.4t3 - 5.4t m, what is most nearly the acceleration of the particle at t = 5s? a. 1.0m/s2 b. 3.4m/s2 c. 18m/s2 d. 100m/s2 3. A truck increases its speed uniformly from 13kph to 50kph in 25s. What is most nearly the acceleration of the truck? a. 0.22m/s2 b. 0.41m/s2 c. 0.62m/s2 d. 0.92m/s2 4. A man driving a car at 65kph suddenly sees an object in the road 20m ahead. Assuming an instantaneous reaction on the driver's part, what constant deceleration is required to stop the car in this distance? a. 7.1m/s2 b. 7.5m/s2 c. 8.0m/s2 d. 8.1m/s2 5. A ball is thrown vertically upward with an initial speed of 24m/s. Most nearly how long will it take for the ball to return to the thrower? a. 2.3s b. 2.6s c. 4.1s d. 4.9s 6. A projectile is launched upward from level ground at an angle of 60deg from the horizontal. It has an initial velocity of 45m/s. How long will it take before the projectile hits the ground? a. 4.1s b. 5.8s c. 7.9s d. 9.5s 7. A car starting from rest moves with a constant acceleration of 15km/hr 2 for 1 hr, then decelerates at a constant 7.5km/hr2 until it comes to a stop. Most nearly how far has it travelled? a. 15km b. 23km c. 25km d. 35km 8. A train with a top speed of 75kph can’t accelerate or decelerate faster than 1.2m/s2. What is the minimum distance between two train stops in order for the train to be able to reach its top speed? a. 300m b. 350m c. 360m d. 365m 9. Today a businessman borrowed money to be paid in 10 equal payments for 10 quarters. If the interest rate is 10% compounded quarterly and the quarterly payment is 2, 000 pesos, how much did he borrow? a. P20, 4000 b. P19, 700 c. P18, 750 d. P17, 500 10. A machine costing P720, 000 is estimated to have a life of 10 years. If the annual rate of depreciation is 25%, determine the total depreciation using the constant percentage or declining balance method. a. P352, 853.34 b. P679, 454.27 c. P764, 243. 33 d. P785, 437.23 11. A copying machine has a useful life of 3 years and a salvage value of P20, 000 was bought for P135, 000. If the owner decides to sell after using it for 2 years, how much should the selling price be so that he will not lose or gain if the interest is 5%? a. P60, 250 b. P74, 750 c. P80, 000 d. P90, 000 12. An item purchased for P25, 000. Annual operation and maintenance cost are P10, 000. Using 10%, what is the capitalized cost for a life service of 10 years? a. P125, 000 b. P130, 680 c. P140, 690 d. P150, 866 13. A motorcycle costs P50, 000 has an expected life of ten years. The salvage value is estimated to be P2, 000 and annual operation costs are estimated at P1, 000. What is the approximate rate of return on the investment if the annual revenue is P10, 000?

a. P2, 007, 983.00

b. P3, 016, 800.00

c. P4, 037, 863.00

d. P5, 007, 883.00

14. A house and lot can be acquired a down payment of P500, 000 and a yearly payment of P100, 000 at the end of each year for a period of 10 years, starting at the end of 5 years from the date of purchase. If money is worth 14% compounded annually, what is the cash price of the property? a. P801, 900 b. P805, 902 c. P808, 811 d. P810, 100 15. A motorcycle costs P50, 000 has an expected life of ten years. The salvage value is estimated to be P2, 000 and annual operation costs are estimated at P1, 000. What is the approximate rate of return on the investment if the annual revenue is P10, 000? a. P3, 016, 800.00 b. P4, 037, 863.00 c. P5, 007, 883.00 d. P2, 007, 983.00 16. The President of a engineering firm wishes to give each of 50 employees a holiday bonus. How much is needed to invest monthly for a year at 12% nominal interest rate, compounded monthly, so that each employee will receive P1, 000 bonus? a. P3, 200 b. P3, 720 c. P3, 890 d. P3, 940 17. The corporation purchased a machine for 1 million. Freight and installation charges amounted to 3% of the purchase price. If the machine shall be depreciated over a period of 8 years with a salvage value of 12%. Determine the depreciation charged during the 5th year using sum of the years digit method. a. P100, 711.11 b. P101, 107. 20 c. P107, 110.00 d. P120,335.55 18. An item is purchased for P100, 000. Annual cost is P18, 000. Using 8%. What is the capitalized cost of perpetual service? a. P325, 000 b. P356, 000 c. P388, 000 d. P425, 000 19. A sum of P1000 is invested now and left for eight years, at which time the principal is withdrawn. The interest that has accrued is left for another eight years. If the effective annual interest rate is 5%, what will be the withdrawal amount at the end of the 16th year? a. P500 b. P706 c. P774 d. P799 20. A spring with a normal length of 30cm is attached to a block of 2kg mass. If the spring is stretched 15 cm, determine the initial acceleration of the block when released. Assume a spring constant of 200 N/m. a. 10 m/s2 b. 20 m/s2 c. 15 m/s2 d. 40 m/s2 21. At her highest point, a girl on a swing is 7 ft above the ground and at her lowest point; she is 3 ft above the ground. What is her maximum velocity? a. 16 ft/s b. 14 ft/s c. 12 ft/s d. 10 ft/s 22. What will be the height (in cm) of the image if an object 5 cm high is placed 1 m in front of a converging lens of focal length 1.5 m? a. 15 cm b. 30 cm c. 45 cm d. 60 cm 23. A light ray is incident on one side of a glass plate at an angle of 45 0. If the index of refraction of the glass is 1.6, compute the angle at which the ray emerges from the other side of the plate. a. 260 b. 200 c. 220 d. 280 24. A 2-ohm heater takes in 5 ampere while submerged in 1400 g of water contained in a vessel with a water equivalent of 100 g. Find the time required for the temperature to change by 80 0 if the system is 90% efficient. (Specific heat of water is 4.19 J/g-0C) a. 11, 173. 33 sec b. 12, 118.55 sec c. 12, 283.33 sec d. 14, 155.47 sec

25. If the ultimate shear strength of a steel plate is 42,000 lb/in 2, what force is necessary to punch a 0.75 in diameter hole in a 0.625 in thick plate? a. 61,850 lbs b. 66,800 lbs c. 63,000 lbs d. 68,080 lbs 26. Calculate the elongation of a solid steel shaft of SAE 1030 carbon steel 2 7/8 inches in diameter by 5 ft in length supporting a direct tension load of 60,000 lbs. The factor of safety is set at 4, stress concentration factor of k=1 and yield strength of 40,000 psi. For steel E=30X106 psi. a. 0.020 b. 0.015 c. 0.0185 d. 0.0166 27. A body weighing 10,000 N was put on top of a 3,502 N/cm spring. What is the deformation of the spring due to the body on top? a. 2.304 cm b. 2.403 cm c. 2.450 cm d. 2.855 cm 28. An axial comprehensive load of 150kN is supported by a cast-iron column. If the outside diameter of the column is 200 mm and the limiting compressive is 50MPa, what is the inside diameter of the column? a. 145.64 mm b. 175.92 mm c. 192.04 mm d. 337.14 mm 29. A steel rod having a cross-sectional area of 150 mm2 is stretched between two fixed points, and the tensile load is 5000N at 200C. At what temperature will the stress be zero? Use α=11.7 µm/m 0C and E=200 GPa. a. 31.4 0C b. 34.2 0C c. 35.7 0C d. 38.5 0C 30. Determine the length of the shortest 2-mm diameter bronze wire which can be twisted trough two complete turns without exceeding a shearing stress of 70 MPa. Use G=35 GPa. a. 1280 mm b. 1658 mm c. 3420 mm d. 6280 mm 31. A 6-m long solid steel shaft is subjected to a torque of 14 kN-m. Determine the minimum diameter of the shaft that will (not) twist through more than 30. Use G=83 GN/m2. a. 112 mm b. 114 mm c. 116 mm d. 118 mm 32. A steel tie rod on bridge must be made to withstand a pull of 5000 lbs. Find the diameter of the rod assuming a factor of safety of 5 and ultimate stress of 64,000 lb/in2. a. 0.75 in b. 0.71 in c. 0.84 in d. 0.79 in 33. Determine the load in kN on a 25 mm diameter X 1200 mm long steel shaft if its maximum elongation will not exceed 1 mm. a. 85 b. 125 c. 103 d. 93 34. A body weighing 1000 lbs falls 6 inches and strikes a 2000 lbs (per inch) spring. What is the deformation of the string? a. 3 inches b. 1000 mm c. 6 inches d. 2 inches 35. During a stress-strain test, the unit deformation of 0.000167 m/m at a stress 35 MPa was observed and it was 0.000667 m/m at a stress of 140 MPa. Determine the strain corresponding of 80 MPa. a. 350.76X10-6m/m b. 380.95X10-6m/m c. 453.67X10-6m/m d. 670.45X10-6m/m 36. Determine the diameter of a solid steel shaft 5 m long which is stressed to 60 MPa when twisted through 4 0. Use G=83 GPa. a. 100 mm b. 104 mm c. 122 mm d. 124 mm 37. Steel railroad rails of 10 m long are laid with a clearance of 3X10 -3m at a temperature of 150C. At what temperature will the rails touch? Use α=11.7X10-6 m/m 0C. a. 27.34 0C b. 38.65 0C c. 40.64 0C d. 53.13 0C

38. Determine the maximum torque that can be applied to a hollow circular steel shaft of 100-mm outside diameter and 70-mm inside diameter without exceeding a shearing stress of 60 MPa. a. 4,648 N-m b. 5,403 N-m c. 3,742 N-m d. 6,263 N-m 39. Building A is 3 times as high as Building B. An apple is dropped from the top of the building A takes t seconds to hit the ground. How long does it take for the apple if it is dropped from Building B? a. tb=

√2 t 3 A

b. tb=

√3 t 3 A

c. tb=

√3 t 2 A

d. tb=

√2 t 2 A

40. A ball is dropped from a balloon at a height of 195m. If the balloon is rising 29.3m/s. Find the velocity of the ball as it strikes the ground? a. 68.44 m/s b. 55.45 m/s c. 46.57 m/s d. 30.64 m/s 41. A man in a hot air balloon drops an apple at height of 100m. If the balloon is rising at 15m/s, find the highest point reach by the apple? a. 100.2m b. 89.74m c. 111.5m d. 95.97m 42. A balloon is ascending at a rate of 16ft/sec at a height of 32ft above the ground when a package is dropped. The time taken, in the absence of air resistance, for the package to reach the ground is: a. 1 sec b. 2.0 sec c. 1.5 sec d. 2.5 sec 43. What is the angle of banking for a highway curve of radius 90m designed to accommodate cars traveling at 160 kph? The coefficient of friction between the tire and the road is 0.60. a. 34.9 degrees b. 43.7 degrees c. 44.9 degrees d. 65.9 degrees 44. Determine the maximum shearing stress in a helical steel spring composed of 20 turns of 20 mm-diameter wire on a mean radius of 80 mm when that spring is supporting a load of 2 kN. Use G = 83 GPa. (September 2014 Board Exam) a. 110.6 MPa b. 112.3 MPa c. 120.6 MPa d. 134.6 MPa 45. A steel marine propeller shaft 14in. in diameter and 18ft long is used to transmit 5000hp at 189 rpm. If G= 12x10 6psi, determine the maximum shearing stress a. 3049.7psi b. 3094.6psi c. 4049.7psi d. 4930.8psi 46. A piston cylinder device initially contains 0.8 m3 of air at 110kPa and 80°C. The air is now compressed to 0.2 m 3 in such a way that the temperature inside the cylinder remains constant. Determine the work done during this process. (September 2014 Board Exam) a. -122kJ b. -123kJ c. -124kJ d. -125kJ 47. A debt of P10000 with 10% interest compounded semi-annually is to be amortized by semi-annual payments over the next 5 years. The first due is 6 months. Determine the semi-annual payments. a. P1925.05 b. P1295.05 c. P1529.05 d. P1259.05 48. A property is bought at P500,000 and is expected to last 50years with a salvage value of P50,000. The depreciation charge during the 20th year of service using Sum-of-the year’s digit method is…. a. P11,546.23 b. P9,000.00 c. P10,941.18 d. P9,456.89 49. If P10,000 is deposited each year for 9 years, how much annuity can a person get annually from the bank every year for 8years starting 1 year after the 9th deposit is made. Cost of money is 14%. a. P34,675.18 b. P23,457.90 c. P28,000.56 d. P34,125.67 50. A manufacturer of native baskets incurs an annual fixed operating cost of P60000. Each native basket costs P200 and sells at P1000. What is the manufacturer’s break even sales volume annually? a. 55 b. 30 c. 75 d. 60

51. Rex borrowed a certain amount on October 1990 from Jason. Two years later, Rex borrowed again from Jason an amount of P500. Rex paid P200 on October 1993 and discharged his balance by paying P700 on October 1995. What was the amount borrowed by Rex on October 1990 if the interest rate is 8% compounded annually. a. P260.51 b. P216.51 c. P206.51 d. P261.51 52. In the following unit cell, what direction is indicted by the arrow?

a. (0 1 2)

b. (2 1 0)

c. (0 1 1/2)

d. (0 1/2 1)

c. (1 1 1)

d. (2 2 2)

c. (1/3 1/2 1)

d. (2 3 6)

53. What are the Miller indices of the given plane?

a. (4 4 4)

b. (1/4 1/4 1/4)

54. What are the Miller indices of the given plane?

a. (3 2 1)

b. (2/6 3/6 6/6)

55. A plane intercepts the coordinate axis at x = 1, y = 3 and z = 2. What are the Miller indices of the plane? a. (1 3 2) b. (6 2 3) c. (1 2 3) d. (3 2 6)

56. The atomic weight of copper is 63.5g/mol. Calculate the theoretical density of copper given that the unit cell is facecentered cubic (FCC) and the lattice parameter is 3.61 Angstrom. a. 4.5g/cm3 b. 8.8g/cm3 c. 7.9g/cm3 d. 9.0g/cm3 57. Determine the planar density of copper atoms in a (1 0 0) plane given that the unit cell is face-centered cubic(FCC) and the lattice parameter is 3.61 Angstrom. a. 7.68x1018 atoms/m2 b. 1.53x1019 atoms/m2 c. 2.30x1019 atoms/m2 d. 3.84x1019 atoms/m2 58. A sample of face-centered cubic nickel (Ni) was placed in an X-ray beam of wavelength 0.154nm. If the lattice parameter for Ni is 0.352nm, what is the 1st-order angle of diffraction most nearly? a. 5.7deg b. 13deg c. 7deg d. 19deg 59. How much heat is needed to melt ice with mass of 0.72 kg initially at -10C to transform to liquid at 10C? (C =2220 kJ/ kg-C) a. 260 b. 270 c. 280 d. 290 60. 4. A 40g of ethanol sample is mixed with 60g of methanol sample. A mole of ethanol and methanol has a mass of 32g and 46g respectively. What is the mole fraction of the solvent? a. 0.51 M b. 0.6 M c. 0.96 M d. 0.7 M 61. What is the molar mass of 5.21g of gas which occupies 3.92L at 105kPa and 25 0C? a. 15.25 g/mol b. 17.54 g/mol c. 23.35 g/mol d. 31.36 g/mol 62. Calculate the mass of Titanium atom. Titanium element has atomic mass of 47.9 amu. a. 5.57X10-21g b. 7.95X10-23g c. 8.67X10-20g d. 8.86X10-23g 63. A 40g of ethanol sample is mixed with 60g of methanol sample. A mole of ethanol and methanol has a mass of 32g and 46g respectively. What is the mole fraction of the solvent? a. 0.51 M b. 0.6 M c.0.96 M d. 0.7 M 64. Three forces 20N, 30N, and 40N are in equilibrium. Find the angle between the 30N and 40N forces a. 25.970 b. 28.960 c. 30015’25” c. 400 65. An automobile accelerates at a constant rate of 15mi/hr to 45mi/hr in 15 seconds while travelling in a straight line. What is the average acceleration? a. 2ft/sec2 b. 2.12ft/sec2 c. 2.39ft/sec2 d. 2.93ft/sec2 66. A baseball is thrown from a horizontal plane following a parabolic path with an initial velocity of 100m/s at an angle of 300 above the horizontal. How far from the throwing point will the ball attain its original level? a. 875m b. 880m c. 883m d. 890m 67. A 50,00N car travelling with a speed of 150km/hr rounds a curve whose radius is 150m. Find the centrifugal force. a. 38kN b. 59kN c. 65kN d. 70kN 68. A sealed tank contains oxygen at 27˚ C at a pressure of 2 atm. If the temperature increases to 100 ˚C what will be the pressure inside the tank? a. 4.92 atm b. 4.29 atm c. 2.49 atm d. 9.24 atm 69. A volume of 400 cc of air is measured at a pressure of 740 mm Hg abs and a temperature of 18 ˚C. What will be the volume at 760 mm Hg and 0 ˚C? a. 376 cc b. 326 cc c. 356 cc d. 366 cc

70. A 50 g mass hangs at the end of the spring. When 20 grams are added to the end f the spring it stretches 7 cm more. Find the spring constant. a. 2.8 b. 2.9 c. 4.3 d. 2.5 71. A hollow cylinder 1 m in diameter and 2 m high weighs 2825 N. How many kN of lead weighing 110 kN/m3 must be fastened to the outside bottom of the cylinder to make it float with 1.5 m submerged in water? a. 8.5 kN b. 6. 5 kN c. 10.5 kN d. 9.5 kN 72. A block of wood floats in water with 5 cm projecting above the water surface. When placed in glycerine of specific gravity of 1.35, the block projects 7.5 cm above the liquid. Determine its specific gravity. a. 0.514 b. 0.704 c. 0.836 d. 0.658 73. A vertical rope is attached to an object that has a mass of 40.0 kg and is at rest. The tension in the rope needed to give the object an upward speed of 3.50 m/sec in 0.700 sec is: a. 592 N b. 392 N c. 200 N d. 720 N 74. John drives for 30 min at 100 km/hr and then stop for 15 min. He then drive for 45 min at 80 km/hr. John’s average speed for the entire trip is: a. 73 km/hr b. 83 km/hr c. 88 km/hr d. 97 km/hr 75. A particle has an initial velocity of 4.8 m/sec towards south and a final velocity of 7.1 m/sec towards east. The particle was subjected to a constant acceleration for 0.25 sec. The magnitude and direction of the acceleration must have been: a. 8.6 m/sec2 at 340 N of E c. 34 m/sec2 at 340 S of E b. 34 m/sec2 at 340 N of E d. 8.6 m/sec2 at 340 S of E 76. A projectile is fired vertically upward with a speed of 62 m/sec. In the absence of air resistance, the maximum height the projectile attains is: a. 2500 m b. 98 m c.200 m d.1900 m 77. A balloon is ascending at a rate of 16 ft/sec at a height of 32 ft above the ground when a package is dropped. The time taken, in the absence of air resistance, for the package to reach the ground is: a. 1.0 sec b. 1.5 sec c. 2.0 sec d. 2.5 sec 78. A block of mass “m” is at rest on an inclined place that makes an angle of 30 0 with the horizontal. Which of the following statements about the force of static friction is true? a. fS > mg b. fS > mg cos 300 c. fS = mg cos 300 d. fS = mg sin 300 79. You want to elope by sliding down a nylon rope made by tying stockings together. The rope will withstand a maximum tension of 300N without breaking. Your mass is 61.2 kg. The magnitude of the smallest acceleration “a” with which you can slide down the rope is: a. 9.81 m/sec2 b. 4.91 m/sec2 c. zero d. 2.40 m/sec2 80. A rope with 1kg block attached to its end has a length of 5m. Find the time period to make it swing. a. 1.43 sec b. 0.22 sec c. 9.63 sec d. 0.63 sec 81. Two bodies, each having a mass of 450 milligrams are separated in space a distance of 10 kilometers apart. The force exerted on each other due to gravitation is _____ Newtons. a. 1.35 x 10-7 b. 1.35 x 10-19 c. 1.35 x 10-9 d. 1.35 x 10-18 82. At Guimaras Island where orchards abound, an extra large mango falls from a branch five (5) meters above the ground. Assuming a “g” of 9.81 m/sec2, the speed of the falling mango is ___ meters/second as it strikes the ground.

a. 9.905

b. 14.905

c. 12.905

d. 8.905

83. In a funny movie, a man in a hot air balloon, 150 meters from the ground drops a bottle of coke that made the life of African tribesmen in great trouble. If the balloon is rising at 15 meters per second, the highest point reached by the bottle is ___ meters. a. 141.50 b. 151.50 c. 161.50 d. 171.50 84. What is the force in Newtons, required to move a car with 1000 kg? Mass with an acceleration of 12.0 meters/sec. a. 12 000 N b. 30 000 N c. 8 000 N d. 6 000 N 85. Two lead balls whose masses are 5 kg and 0.5 kg are placed with their center 50 cm apart. With what force do they attract each other? a. 6.67 x 10-10 N b. 6.67 x 10-11 N c. 6.67 x 10-8 N d. 6.67 x 10-9 N 86. What retarding force is required to stop a 0.45 caliber bullet of mass 20 grams and speed of 300 m/sec as it penetrates a wooden block to a depth of 2 inches? a. 17,716 N b. 15,500 N c. 19,645 N d. 12,500 N 87. A flywheel of radius 14 inches is rotating at the rate of 1000 rpm. How fast does a point on the rim travel in ft/sec? a. 122 c. 100 c. 1456 d.39 88. Pedro started running at a speed of 10 kph. Five minutes later, Mario started running in the same direction and catches up with Pedro in 20 minutes. What is the speed of Mario? a. 12.5 kph b. 17 kph c. 14.5 kph d. 13.5 kph 89. A 900 N weight hangs on a vertical plane. A man pushes this weight horizontally until the rope makes an angle of 400 with the vertical. What is the tension in the rope? a. 1286 N b. 918 N c. 1175 N d. 825 N 90. A highway curve with radius 800 ft is to be banked so that a car travelling 55 mph will not skid sideways even in the absence of friction. At what angle should the curve be banked? a. 0.159° b. 6.41° c. 75° d. 14.2° 91. An elevator weighing 4000 Ib attains an upward velocity of 4 m/sec in 3 sec with uniform acceleration. Find the apparent weight of a 40 kg man standing inside the elevator during its ascent. a. 339 N b. 446 N c. 245 N d. 795 N 92. A boat moving at 12 kph is crossing a river 500 m wide in which a current is flowing at 4 kph. In what direction should the boat head if it is to reach a point on the other side of the river directly opposite its starting point? a. 19.47 downstream b. 19.47 upstream c. 18.43 downstream d. 18.43 upstream 93. Find the location of the centroid of the composite area consisting of a 10 in square surmounted by semi circle. The centroid of a semicircle is located 4r/3π above the base (diameter) of a semi circle of radius r. a. 6 in from bottom b. 6.2 in from bottom c. 6.4 in from bottom d. 7 in from bottom 94. Two mirrors, each 1.6 m long, are facing each other. The distance between the mirrors is 20 cm. A light incident on one end of one of the mirrors is at an angle of incidence of 30 0. How many times is the ray reflected before it reaches the other end? a. 12 b. 14 c. 16 d. 24 95. What is the resulting pressure when one pound of air at 15 psia and 200 F is heated at constant volume to 800 F? a. 15 psia b. 28.6 psia c. 36.4 psia d. 52.1 psia

96. A chef heated a bowl of soup of 30°C 10 45°C, what is the change in temperature in Fahrenheit scale? a. 15°F b. 27°F c. B. 30°F d. 42°F 97. What is the new length of a bar made of pure gold at 75°C if it has a length of 0.3 meters at 10°C? a. 0.30273 m b. 0.3273 m c. 0.30385 m d. 0.3385 m 98. What is the increase in temperature necessary for a hydrogen gas, initially at 0°C, to increase its volume by 5% at constant pressure? a. 4.5°C b. 7.8°C c. 12.5°C d. 13.7°C 99. A steel tank is filled with 15 gallons of gasoline when the temperature is 22°C. The tank and the gasoline inside are then heated by the Sun’s rays to a temperature of 40°C. How much of the gasoline will spill from the tank? ( αsteel= 12 x 10-6 ; βgasoline= 0.95 x 10-3 ) a. 0.1389 gallons b. 0.1938 gallons c. 0.2479 gallons d. 0.2565 gallons 100. A new temperature scale is being developed in a certain laboratory. On this new scale, the freezing point of water and the boiling point of water are 150°X and 300°X, respectively. What is the temperature in the Fahrenheit scale that is equivalent to 470°X? a. 200°C b. 206.7°C c. 213.3°C d. 219.8°C