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MCAT Practice

Text of Full length 8 answers

  • 1. MCAT Full-Length TestsDear Future Doctor,The following Full-Length Test and explanations are an opportunity to bring it all togetherin simulation. Do not engage in Full-Length practice until you have adequately preparedyour knowledge and critical thinking skills in Subject, Topical, and Section tests. Simplyg the tests is inadequate; a solid understanding of your performance through your ScoreReports and the explanations is necessary to diagnose your specific weaknesses andaddress them before Test Day.All rights are reserved pursuant to the copyright laws and the contract clause in yourenrollment agreement and as printed below. Misdemeanor and felony infractions canseverely limit your ability to be accepted to a medical program and a conviction canresult in the removal of a medical license. We offer this material for your practice in yourown home as a courtesy and privilege. Practice today so that you can perform on testday; this material was designed to give you every advantage on the MCAT and we wishyou the best of luck in your preparation.Sincerely,Albert ChenExecutive Director, Pre-Health Research and DevelopmentKaplan Test Prep 2003 Kaplan, Inc.All rights reserved. No part of this book may be reproduced in any form, by Photostat, microfilm,xerography or any other means, or incorporated into any information retrieval system, electronicor mechanical without the written permission of Kaplan, Inc. This book may not be duplicated,distributed or resold, pursuant to the terms of your Kaplan Enrollment Agreement.

2. PHYSICAL SCIENCES ANSWER KEY11. D2. D3. A4. B5. D6. A7. A8. A9. C10. C11. C12. B13. B14. A15. D16. A17. B18. A19. D20. D21. D22. B23. B24. D25. D26. D27. B28. A29. C30. B31. D32. D33. A34. C35. B36. D37. C38. C39. D40. D41. A42. B43. C44. C45. D46. C47. C48. D49. A50. A51. D52. D53. C54. A55. D56. C57. A58. B59. D60. D61. C62. C63. A64. D65. D66. B67. A68. B69. A70. D71. C72. B73. C74. B75. B76. B77. C 3. Passage I (Questions 1-6)1. DAt first glance, it might seem that only three hydrogen bonds are possible for each boric acidmolecule, since there are three hydroxyl groups. However, each hydroxyl group has a hydrogenatom with one possible H-bond and an oxygen atom with two lone pairs; two more possible H-bonds.Therefore, each hydroxyl group is capable of forming three hydrogen bonds; there arenine possible hydrogen bonds for each boric acid molecule.2. DAccording to the passage, solubility is determined by the intermolecular reactions both insolvent-solute interactions and solute-solvent interactions. In order to arrive at the correctanswer, consider each Roman numeral separately. Statement I is true; acetylene molecules arenonpolar because of their symmetry, while water molecules are very polar. Since the polarity ofacetylene molecules differs greatly from that of water molecules, acetylene will interfere withthe hydrogen bonding between water molecules, thereby lowering their miscibility. Since state-mentI is true, you can eliminate choice (B). Now consider statement II. The intermolecularinteraction between acetylene and water is weak because of the different polarities of the twomolecules, so this statement is true. Eliminate choice (A), since it does not contain statement II.Finally, consider statement III. Acetylene is not capable of hydrogen bonding because it does notcontain an electronegative element, so the statement is true. Since all three statements are true,choose (D).3. ABefore you consider the explanations provided in the answer choices, ask yourself how theinformation in the passage might be relevant to the question. The passage discusses hydrogenbonding, so the answer to the question will probably have something to do with hydrogen bond-ing.Ammonia is capable of hydrogen bonding because it contains nitrogen, a highly elec-tronegativeelement, bonded to hydrogen. X-ray studies suggesting more hydrogen bonding thanpredicted would indicate higher attractive intermolecular forces and raise the melting point, sochoice (A) makes sense. Choice (B) would decrease the melting point, since the moleculeswould have decreased intermolecular interactions. (C) and (D) are irrelevant to the meltingpoint.4. BThe passage states that the structure of ammonium chloride is a cubic arrangement of 8 Cl-around+. This is a simple description of a body centered cubic crystal as showna single NH4below. Therefore, the answer is B. The MCAT also expects you to be able to distinguish betweensimple cubic and face centered cubic structures, so keep those in mind as well and youll be pre-paredfor any structure that appears on the exam.5. DThe passage states that the heat of vaporization is affected by both the number of hydrogenbonds and inhibition of rotation. The molecules in choices (A), (B), and (C) are all capable of2 4. multiple H-bonds and have three-dimensional geometry. HCN is not capable of H-bondsbecause the hydrogen is not bonded to an electronegative element in HCN. In addition, its lin-eargeometry allows rotation to occur even when the molecules are bonded in series:H C N: H C N: H C N:Therefore, the answer is (D).6. AWhile many H-bonding molecules are soluble in water this is not a requirement for H-bonding.Large organic molecules containing a single hydroxyl group can form hydrogen bonds and yet beinsoluble in water. Therefore, choice (A) is correct. (B) is incorrect because an available lone elec-tronpair is necessary for hydrogen bonding to occur; if the electronegative element doesnt have alone pair of electrons, it wont be able to bond to a hydrogen atom. Choice (C) is incorrect becausethe hydrogen atom must be slightly acidic in order for the H-bonding to occur. This is a consequenceof the fact that a polar bond will lead to a more acidic hydrogen atom than a nonpolar bond. Choice(D) is incorrect because the two molecules must be in close proximity for an intermolecular bondsuch as hydrogen bonding to occur. Again, the answer is (A).Passage II (Questions 7-12)7. AAccording to Equation 1, the speed of a seismic wave in water equals the square root of its bulkmodulus B divided by its density . Therefore, we set up the expression,22.4v1.00 0 g1/3 a0c 8mP1.4103 m/s.This is closest to choice (A). Be sure to watch the units on the table. The density is given asg/cm3 and must be changed to kg/m3 in an expression necessarily involving Pa.8. ASolid 1 will store more potential energy. This question requires integrating information drawnfrom the passage with information regarding compressibility, restoring forces, and potential energyin springs: A large bulk modulus is essentially equivalent to a large spring constant, k, in the mediumthrough which sound is traveling. We know this because the passage tells us that a large B indicatesa large restoring force in response to compression (see paragraph 3). Potential energy is proportionalto k (recall U=1/2 kx2 for springs). Thus, the atoms in solid 1 will be able to hold more potentialenergy; choice (A) is correct.9. CThe wavelength of any wave is given by the expression v=f, where f is the frequency and isthe wavelength. This formula is an MCAT favorite. The speed v of a seismic wave in a rock near theEarths surface = 6000 m/s (paragraph 2). Thus, = v/f = (6000 m/s) / (5000 Hz) = 1.2 m, choice(C).10. CRecall that the speed of the wave depends on , , and B. Reading the question stem carefullyreveals that we want to find which answer choice will independently explain the difference in wavespeed. The surface wave has a smaller speed than the core wave (see paragraph 2): A smaller shear3 5. or bulk modulus or a larger density could explain a decreased wave speed. Likewise, a larger shearor bulk modulus or a smaller density would explain an increased wave speed in the core wave.Choice (C) is the correct answer. Temperature has not been discussed in the passage eliminatechoice (D).11. CAgain, Equation 1 tells us what we need to know. Now consider that vA/vB = 3/1 =So B/A = 9/1, and the ratio of the density of Soil A to Soil B is 1:9;the correct answer is choice (C).12. BSeismic waves are longitudinal waves. If a seismic wave is traveling through a solid, then itsmolecules are moving parallel to the movement of the wave, in this case horizontally. Since the solidis immobile, there is no vertical movement of the molecules, and so their kinetic energy in the ver-ticaldirection is zero choice (B) is correct. Remember that the MCAT is primarily a critical think-ingtest; knowing your concepts will get you a long way.Passage III (Questions 13-18)13. BAs heat is transferred to the bath, the ice begins to melt. Since ice has a smaller density thatwater, its melting will decrease the volume of the bath. Here the height of the bath increases, sovolume increases: therefore, we are not melting ice, but freezing water. Heat must be transferredfrom the bath! The only way to spontaneously transfer heat from the bath is to add a substancewith a lower temperature. Choice (B) is the only choice with a substance at a lower than zerotemperature. Therefore, choice (B) is correct. All the other substances listed would either trans-ferheat to the bath or not at all.14. AThe passage states that heat transfer between two substances is directly proportional to thetemperature difference between those two substances. So, before thermal equilibrium is reached,the bath with a temperature farthest away from 68C will experience the fastest (so after 10 sec-onds,the most) heat transfer. Eliminate choice (D), since ice will not exist at 32C and 1 atm.Dont be tempted by this choice; it is designed to test whether you are confusing the Celsius andFahrenheit scales. Choice (A) is correct, since it sets up the largest temperature gradient betweenthe bath and the substance.15. DStraightforward calculation question. We know that all the heat lost from the unknown sub-stanceis gained by the bath: Qsub = Qbath. In addition, both the substance and water ended up at15.