Physics section test (1)

MCAT Section Tests Dear Future Doctor, The following Section Test and explanations should be used to practice and to assess your mastery of critical thinking in each of the section areas Topics are confluent and are not necessarily in any specific order or fixed proportion This is the level of integration in your preparation that collects what you have learned in the Kaplan classroom and synthesizes your knowledge with your critical thinking Simply completing the tests is inadequate; a solid understanding of your performance through your Score Reports and the explanations is necessary to diagnose your specific weaknesses and address them before Test Day All rights are reserved pursuant to the copyright laws and the contract clause in your enrollment agreement and as printed below Misdemeanor and felony infractions can severely limit your ability to be accepted to a medical program and a conviction can result in the removal of a medical license We offer this material for your practice in your own home as a courtesy and privilege Practice today so that you can perform on test day; this material was designed to give you every advantage on the MCAT and we wish you the best of luck in your preparation Sincerely, Albert Chen Executive Director, Pre-Health Research and Development Kaplan 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, electronic or 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 Physical Sciences Test Time: 40 Minutes Number of Questions: 31 MCAT PHYSICAL SCIENCES DIRECTIONS: Most of the questions in the following Physical Sciences test are organized into groups, with a descriptive passage preceding each group of questions Study the passage, then select the single best answer to each question in the group Some of the questions are not based on a descriptive passage; you must also select the best answer to these questions If you are unsure of the best answer, eliminate the choices that you know are incorrect, then select an answer from the choices that remain Indicate your selection by blackening the corresponding circle on your answer sheet A periodic table is provided below for your use with the questions PERIODIC TABLE OF THE ELEMENTS GO ON TO THE NEXT PAGE as developed by Physical Sciences Passage I (Questions 1–8) Malachite is a green semiprecious stone with the molecular formula CuCO3 • Cu(OH)2 Malachite is widespread in nature, occurring near copper deposits, and can also be synthesized in the laboratory Three experiments were carried out to investigate some of the chemical properties of malachite In each experiment, evolved gases were collected in the following apparatus: a rubber tube was connected at one end to a reaction vessel; the free end of the tube was inserted into collection bottles inverted in a tub of water, allowing gas to displace the water in the bottle The bottles were corked and set aside for later analysis A B C D A 44 g sample of malachite was placed in the reaction vessel, and an aqueous sulfuric acid solution was added to the vessel Shortly, gas evolved from the free end of the tube When the reaction was complete, a strip of pH paper inserted into the aqueous solution in the reaction vessel showed it to be neutral Experiment Three gas-filled collection bottles were taken from each of the above experiments A burning splint was inserted into the mouth of one bottle from each experiment; in each case, the flame was extinguished immediately Water, 25 mL, was then added to the second bottle from each experiment, and the bottle was corked and shaken Strips of pH paper dipped in the water turned pink in both cases Finally, 50 mL of calcium hydroxide solution were added to the third bottle from each experiment, and the bottles were shaken A milky white solution was observed in each 29% 36% 50% 67% The reaction that occurred in Experiment can be classified as a(n): A B C D Experiment oxygen water vapor carbon dioxide hydrogen What is the percent composition of oxygen in malachite? A B C D The following experiments were performed: Experiment A 22 g sample of malachite was placed in the reaction vessel and the bottom of the vessel was heated rapidly After a short time, a black solid appeared in the bottom of the reaction vessel, condensation appeared on the flask, and gas bubbled through the free end of the tube into the collecting bottles The black solid was identified as copper (II) oxide The gas collected in Experiments and was most likely: acid-base reaction double displacement reaction redox reaction decomposition reaction Assume the gas collected in Experiment is pure If the volume of each collection bottle is 100 mL, how many bottles will be needed to collect all the gas produced? (The conditions are STP.) A vessels B vessels C 22 vessels D 23 vessels Which of the following statements is true of Experiment 2? A An excess of sulfuric acid was added to the reaction vessel B An aqueous copper sulfate solution was formed C An aqueous copper hydroxide solution was formed D The pH paper turned blue upon contact with the reaction solution GO ON TO THE NEXT PAGE KAPLAN MCAT If stoichiometric amounts of calcium hydroxide solution were used in Experiment 3, the final solution would be: A B C D If Experiment were performed with aqueous hydrochloric acid rather than sulfuric acid, you would expect the products to be: A B C D neutral acidic basic Cannot be determined Cu(s), Cl2(g), CO2(g), H2O CuCl2(aq), H2O, CO2(g) HCl(aq), H2CO3(aq), H2O CuCl2(aq), Cu(s), H2CO3(aq) When the copper oxide produced in Experiment was weighed, it was found that g had been produced What was the percent yield of copper oxide from this experiment? A 18% B 25% C 50% D 100% Passage II (Questions 9–13) There are situations in which matter may be converted into energy This occurs, for example, in the formation of a nucleus, the mass of which is found to be slightly less than the sum of the masses of the individual protons and neutrons Another instance in which this occurs is in the process of nuclear fusion, which describes the reaction when two smaller nuclei are brought together under certain conditions and join together to form a larger nucleus, resulting in the release of large amounts of energy In the sun’s core, for example, hydrogen atoms combine to form one helium atom By this process the sun produces x 1026 J of energy every second Energy can be released not only by fusing smaller nuclei but by splitting larger ones This process is known as nuclear fission For example, when uranium is bombarded with neutrons, it is split into two smaller nuclei and energy is released This particular nuclear reaction also releases more neutrons, which can cause further fission reactions with other uranium nuclei and thus lead to a self-sustaining chain reaction In nuclear reactors, this process is controlled by inserting control rods, made of elements such as cadmium, that absorb some of the neutrons without undergoing a fission reaction themselves A typical uranium fission reaction is shown below 235 92 U + 10 n→ 139 54 Xe + Y + 30 n What is the product Y formed by this reaction? A 94 36 Kr B 92 38 Sr C 94 38 Sr D 139 54 Xe GO ON TO THE NEXT PAGE as developed by Physical Sciences 10 The total energy that it takes to separate a nucleus into its individual protons and neutrons is called the binding energy This energy: A is sufficient to sustain a chain reaction B is equal to the total mass of the nucleus times the speed of light squared C is equal to the mass defect of the nucleus times the speed of light squared D is equal to the kinetic energy of a β – particle ejected during beta decay 13 Fission reactions can be initiated by bombarding nuclei with neutrons Would bombarding with protons work just as well? A Yes, because protons and neutrons are both present in the nucleus B Yes, because protons and neutrons have approximately the same mass C No, because protons not have as high a binding energy as neutrons and thus not as energetic D No, because neutrons, unlike protons, not experience electrostatic repulsion from the nucleus 11 The neutrons that are released during a fission reaction are first passed through a magnetic field, and then through an electric field They are: A deflected by the magnetic field only B deflected by the electric field only C deflected by both the magnetic field and the electric field D not deflected at all 12 90 38 Srdecays by emitting an alpha particle to form a 86 stable isotope of krypton, 36 Kr If after 19 hours 75% of the sample has decayed, what is the half life of the reaction? A 4.8 hours B 9.5 hours C 14 hours D 29 hours GO ON TO THE NEXT PAGE KAPLAN MCAT Passage III (Questions 14–18) Enzymes are biological molecules that increase chemical reaction rates An enzyme does not change the equilibrium constant, but merely catalyzes the reaction, reducing the energy required to bring the substrate to the transition state Simple enzymes have a single catalytic site, and their rate of catalysis is directly proportional to the amount of substrate available, up to the point where there is so much substrate that all the catalytic sites have been filled This pattern produces a hyperbolic plot of reaction velocity vs substrate concentration, with Vmax as an asymptote To simplify calculations, this hyperbolic graph can be transformed into a straight-line graph, using the Michaelis-Menten equation: 1/V = (KM/Vmax)(1/[S]) + 1/Vmax Equation where V is the velocity of the reaction, [S] is the substrate concentration, and KM, called the Michaelis constant for the reaction, is the substrate concentration that gives a reaction rate of Vmax/2 y = 1/V slope = K M/V max (0, 1/V max ) Figure x = 1/[S] Figure The catalytic activity of an enzyme can be inhibited in two ways In competitive inhibition, the catalytic site is filled by a molecule other than the substrate Competitive inhibition can be overcome by increasing the concentration of the substrate Noncompetitive inhibition is caused by binding to a regulatory site other than the catalytic site This can cause a change in the shape of the entire molecule, interfering with its catalytic activity The following table records rates of catalysis at different concentrations of substrate for a reaction carried out with and without a noncompetitive inhibitor Table Substrate conc inhibitor) 1.0 x 10–5 M 1.5 x 10–5 M 3.0 x 10–5 M V(without inhibitor) 10 µM / 12 µM / 15 µM / V(with 5.0 µM / 6.0 µM / 7.5 µM / 14 The presence of an enzyme alters the: A B C D energy level of the reactants energy level of the products energy of activation change in free energy of the reaction GO ON TO THE NEXT PAGE as developed by Physical Sciences 15 In competitive inhibition: KM increases KM decreases Vmax increases Vmax decreases 16 In the reaction illustrated in Table 1, the effect of the inhibitor is to: b °C B c 18 KM for a given reaction would vary with the: I II III IV A B C D pH temperature concentration of enzyme concentration of substrate I and II only I, II, and III only I, II and IV only I, II, III, and IV time D A → B → C → D A Both bind at the catalytic site B They bind at different regulatory sites C B binds at the catalytic site, and D at a regulatory site D B binds at a regulatory site, and D at the catalytic site °C time temperature 17 In the biochemical pathway shown below, both B and D are found to inhibit enzyme a Increasing the concentration of A overcomes inhibition by B but not by D At what locations B and D bind to a? a C temperature A increase KM decrease KM increase Vmax decrease Vmax temperature A B C D 19 An insulated cylindrical container whose volume is 2500 cm3 is filled with water at a temperature of 30°C If the water is heated by a 2000 W immersion heater, which of the following could be a graph representing the temperature of the water as a function of time for the first 100 s, assuming a constant specific heat? temperature A B C D Questions 19 through 23 are NOT based on a descriptive passage °C time °C time 20 Which of the following elements, each in their ground state, has a partially filled d subshell? A B C D B Si Mg Cr 21 Two identical conducting spheres on insulating supports carry charges of magnitude +Q and +2Q respectively When they are separated by a distance of d the electrostatic repulsive force is F The spheres are made to touch and then restored to their original separation d If there is no loss of charge, what is the new force of repulsion? A F/2 B 3F/4 C 8F/9 D 9F/8 GO ON TO THE NEXT PAGE KAPLAN MCAT 22 Which of the following does not have an electronic configuration of 1s2 2s2 2p6 3s2 3p6? A B C D Ar Cl– K+ Ga3+ 23 A source emits light of wavelength 600 nm for 0.01 µs How many complete waves are sent out? (Note: Speed of light = x 108 m/s) A B C D 5.0 1.8 5.0 5.0 x 106 x 108 x 109 x 1019 Passage IV (Questions 24–31) A sports car with a total mass of 1000 kg can accelerate from rest to 28 m/s in seconds The coefficient of static friction µs, which is a measure of the maximum resistance between the tires and the road when there is no sliding, equals 0.6 The coefficient of kinetic friction µk, which is a measure of the resistance between the tires and the road when the tires slide (skid), equals 0.2 The optimum braking technique is to apply the maximum possible force that is consistent with the car tires not skidding This performance car has a sophisticated anti-lock braking system, such that if the car starts to skid, the braking mechanism is overridden, and the tires are allowed to continue turning so that they can stop skidding and regain their grip on the road At this point the brakes are automatically reapplied, as long as the driver is still depressing the brake pedal This process repeats approximately twenty times a second The braking system itself works on the principle of the hydraulic lever When the driver presses the brake pedal, a piston exerts a force on the brake fluid The pressure that results from this force is transmitted throughout the liquid and presses against the brake shoe piston This in turn presses against the brake shoe, which applies a force on the wheel and stops the car (Note: Assume that the acceleration due to gravity (g) equals 9.8 m/s2.) 24 If the car starts from rest and maintains a constant acceleration for 8.0 s, what is the ratio of the distance traveled in the first four seconds to the distance traveled in the last four seconds? A B C D 1:2 1:3 1:4 1:1 25 The engine of the car is turbo-charged, thereby doubling the net force on the car The time that it takes for the car to accelerate from the rest to a speed of 28 m/s will: A B C D be 1/4 as long be 1/2 as long remain unchanged be twice as long GO ON TO THE NEXT PAGE as developed by Physical Sciences 26 The coefficient of static friction µs is a measure of the car’s ability to keep from sliding sideways during a turn on an unbanked surface The maximum sideways force that the car can sustain without sliding will: A B C D increase if the velocity of the car increases decrease if the velocity of the car increases increase if the mass of the car increases decrease if the mass of the car increases 27 The area of the “contact patch” (the surface of tire in contact with the road) for each of the tires is A If the car is stationary on a level surface, and if each tire provides the same support, what is the pressure being exerted on the surface? (m = mass of the car.) mg A B mg mg C 4A 4mg D A A 28 The car is parked on a slope that makes an angle θ with the horizontal If the handbrake is then released, and the car is allowed to roll down the slope, which of the following graphs represents the acceleration of the car versus the displacement? 29 The car is traveling at a velocity of 24 m/s along a level road What is the shortest time it will take for the car to come to rest? (Assume that the car does not skid, and neglect air resistance.) A 3.1 s B 4.1 s C 4.8 s D 12.2 s 30 How does the surface area of the brake shoe piston compare to the surface area of the brake pedal piston? A The brake shoe piston is larger so the force exerted on the wheels is greater B The brake shoe piston is larger to increase the coefficient of friction between the brake shoe and the wheels C The brake pedal piston is larger to maximize the pressure D The brake pedal piston is larger to increase the contact between the brake pedal and the brake shoe 31 The car is parked on a hill when the handbrake cable snaps, causing the car to roll down the hill into a lake If the car displaces 0.5 m3 of water, what is the apparent weight of the car? (Note: The density of water is 1000 kg/m3.) A 0N B 4,900 N C 9,800 N D 29,400 N END OF TEST KAPLAN MCAT ANSWER KEY: C B D D B A B B C 10 C 10 11 D 12 B 13 D 14 C 15 A 16 D 17 C 18 B 19 C 20 D 21 D 22 D 23 A 24 B 25 B 26 C 27 C 28 A 29 B 30 A 31 B ...Physical Sciences Test Time: 40 Minutes Number of Questions: 31 MCAT PHYSICAL SCIENCES DIRECTIONS: Most of the questions in the following Physical Sciences test are organized into groups,... displacement? 29 The car is traveling at a velocity of 24 m/s along a level road What is the shortest time it will take for the car to come to rest? (Assume that the car does not skid, and neglect... the car? (Note: The density of water is 1000 kg/m3.) A 0N B 4,900 N C 9,800 N D 29,400 N END OF TEST KAPLAN MCAT ANSWER KEY: C B D D B A B B C 10 C 10 11 D 12 B 13 D 14 C 15 A 16 D 17 C 18 B 19