56. Cobalt Co Co has a half-life of 5 years. If there was sample of that isotope with an initial mass of 240 g, how much of the sample remains after 30 years?
(A) 30 g
(B) 15 g
(C) 7.5 g
(D) 3.75 g
(E) 0.89 g

52. The Figure shows a planet moving about the sun in an elliptical orbit. Its speeds at the following four points shown in the Figure are , repsectively. Which of the following statement is correct? (A)(B)(C)(D)(E) none of the above

53. A patient is undergoing radiation therapy. A radioactive isotope decays and emits an a particle with an initial velocity of 2×107 m/s. The a particle is slowed down by the Coulomb force from a nearby nucleus, experiencing a deceleration of 5× m/s². How far will the a particle travel before coming to a stop? (A) 0.1 meters (B) 0.2 meters (C) 0.3 meters (D) 0.4 meters (E) 0.5 meters

54. A patient's prosthetic leg, weighing 5 kg, is sliding across the floor with a coefficient of kinetic friction of 0.2. What is the force of friction acting against the leg? (g = 9.8m/s²) (A) 9.8 N (B) 1N (C) 49 N (D) 1.96 N (E) 245 N

55. How long will it take for an oscillator at a frequncy of 2.5 Hz to make 100 vibrations? (A) 250 s (B) 40 s (C) 25 s (D) 4 s (E) 0.025 s

57. Unpolarized light of the intensity I0 passes through two polaroids. The axis of the first polaroid is vertical. The second polariod is at 30° to the vertical. Find the intensity of the transmitted light. (A) (3/4)I0 (B) (3/8)I0 (C) (1/4)10 (D) (1/8)I0 (E) (1/2)I0

58. The following equation shows the decay process of uranium-238 through the emission of an a-particle: . Which of the following is the element X? (A)(B) (C)(D)(E)

59. Suppose a healthy bone can withstand compressive stress of 181 N/mm² before breaking. If the cross-sectional area of the bone is 3.2 cm², how much weight (in kg) can it support? (gravitational acceleration g = 9.8m/s²) (A) 2790 kg (B) 3240 kg (C) 5910 kg (D) 2072 kg (E) 4790 kg

60. The light intensity incident on a metallic surface produces photoelectrons with a maximum kinetic energy of 2 eV. The light intensity is doubled. Determine the maximum kinetic energy of the photoelectrons (in eV). (A) 4 eV (B) 2 eV (C) √2 eV (D) 1 eV (E) 8 eV

61. Arrange the steps below in the order required to perform a Kjeldahl Nitrogen Analysis. I Distillation of ammonia into standard hydrochloric acid. II Neutralize ammonium to release ammonia.  III Digest the organic sample with boiling sulfuric acid to convert nitrogen to ammonium. IV Titrate unreacted standard hydrochloric acid with sodium hydroxide. (A) III, II, I, IV (B) II, I, IV, III (C) I, IV, III, II (D) IV, III, II, I (E) III, I, IV, II

62. What is the product of the following reaction? (A)(B)(C)(D)(E)