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The Medical College Admission Test (MCAT) is the applicant screening exam used by medical colleges in the United States. It is given a couple dozen times a year at Prometric testing centers, and the vast majority of people who take it are in their junior or senior year of college. The exam is designed to measure the knowledge and skills that are critical for success in medical college and a subsequent medical career - knowledge of scientific principles and concepts, critical thinking, and problem solving. There are three sections on the current version of the test - Physical Sciences, Verbal Reasoning, and Biological Sciences. For the 2013 and 2014 version, there is also an optional trial section which will cover several topics: biology, psychology, and sociology, or biology, physics, chemistry, and biochemistry. The Writing Sample section has been removed from the exam.
For decades, the exam was taken with pencil and paper. In 2007 that changed, and the exam is now taken by computer only. However, it is not an adaptive test, which means that the difficulty level of questions is not adjusted based on the responses to previous questions. The Physical Sciences section has 52 questions with a time limit of 70 minutes. The Verbal Reasoning section has 40 questions with a 60 minute time limit. The Biological Sciences section consists of 52 questions with a 70 minute time limit. All questions are multiple choice, and test takers may choose to take a 10 minute break between the second and third sections of the exam.
The Verbal Reasoning portion does not require any specialized knowledge. Science topics covered on the other two sections include eukaryotic cells and tissues, molecular structure and chemical spectra, oxygen containing compounds, amines, phase equlibria, rate processes in chemical reactions, thermochemistry, microbiology, genetics, electrostastics, translational motion, organic chemistry concepts, and many, many more.
Scores from the three sections are combined and turned into a scaled score, ranging from 3 to 45. Anyone not happy with their performance on the MCAT may void the results at any time during the test, and for up to five minutes after the test has ended. A person may only take the exam three times in one year. The MCAT is one of the most difficult tests in existence, and anyone hoping to go to medical school would be well advised to take advantage of some of the excellent prep guides on the market.
MCAT Practice Questions
1. Methane gas is burned in pure oxygen at 200 °C and 1 atm of pressure to produce CO2 and H2O according to the equation
CH4 + 2O2 → CO2 + 2H2O
If 10 L of methane gas were burned, and the final temperature and pressure remained the same, how many liters of gaseous products are produced by the reaction?
- 10 L
- 20 L
- 30 L
- 40 L
2. 10 g of salt XY (MW = 100 g/mol) is added to 1 liter of water with stirring. The salt dissociates into ions X+ and Y-. After equilibrium is established, the undissolved portion of the salt was removed by filtration, weighed, and found to be 9.5 g. What is the Ksp for this salt?
- 5 x 10-2
- 5 x 10-3
- 1 x10-2
- 2.5 x 10-5
3. For the conversion of water into steam, which of the following is true?
- ΔT=0, ΔS>0
- ΔT>0, ΔS = 0
- ΔT =0, ΔS <0
- ΔT >0, ΔS >0
4. The speed of a travelling wave in a stretched string is given by, where √T/μ is the tension in the string and μ is the mass per unit length. A 2 meter long stretched string with a mass of 0.010 kilograms is made to resonate with standing waves at 50 Hz. What tension in the string is needed to produce the fourth harmonic? (Note: the fourth harmonic fits 2 full waves into the length of the string).
- 12.5 newtons
- 25 newtons
- 50 newtons
- 10,000 newtons
5. FELICITY : SADNESS :: IGNOMINY :
6. ABATE : INCREASE :: ABHOR
7. A _____ personality is a necessity for a comedian.
8. In oxidative phosphorylation, high-energy electrons are passed from NAD and FADH2 down the electron transport chain to a final electron acceptor. Which of the following is that electron acceptor?
9. Reaction between alkyl halides and primary amines
- produce 2° amines
- produce 2° and 3° amines
- produce 2° and 3° amines and quaternary ammonium salts
- do not occur
10. The addition of an anionic species to the β position of an α,β-unsaturated ketone is called a
- Michaelson-Morley experiment
- Michaelson reaction
- Michael addition
- Mitchell addition
Answers & Explanations
1. C: The equation shows that for every liter of methane reacted, one liter of CO2 and 2 liters of water vapor will be produced. So a total of three liters of gaseous products will be formed for every liter of methane burned. Because the temperature of the reaction products is 200° C, the water produced will be in vapor (gas) form and not in liquid form. Since 10L of methane were burned, 30 L of gaseous products were formed.
2. D: 0.5 g of the salt dissolved, which is 0.005 mol of the salt. Since the volume is 1 L, the molarity of the salt is 0.005 M. This means that both species X and Y are present at 0.005 M concentration. The Ksp = [X][Y], or [0.005][0.005] which equals 2.5 x 10-5.
3. A: When liquid water changes to steam, the temperature is constant, as in all phase changes. The entropy increases due to the increase in disorder from a liquid to a gas.
4. A: For standing waves, the string must be fixed at both ends. The wavelength at the fundamental frequency is 4 meters and the wavelength when the string resonates at the fourth harmonic is 1 meter. Using the wave equation v = λf, the frequency at the fourth harmonic is v/1 m = 50 Hz. Hence the necessary speed is 50 m/s. Furthermore, the mass per unit length is 0.01 kg / 2 meters = 0.005 kg/m. Thus the tension is the string is v2μ = 502 x 0.005 = 12.5 newtons.
5. D: This is an analogy based on antonyms. Felicity, or happiness, is the opposite of sadness, just as ignominy, or disgrace, is the opposite of honor.
6. B: This analogy is based on antonyms. Just as abate means the opposite of increase, so does abhor mean the opposite of love.
7. B: Ask yourself what kind of personality a comedian should have. Would it be menial (meaning "low," "fit for servants")? Obviously not. Would it be jocular (meaning "full of fun, joking, humorous")? Obviously so. The other two choices do not fit a comedian's personality. Reticent means "shy and withdrawn." Bombastic means "pompous" and "using language that sounds grand but means nothing."
8. D: Oxygen is the final electron acceptor, which is why oxygen is required for cellular respiration. Oxygen combines with two electrons and two protons to form water, one of the waste products of cellular respiration. The other waste product is carbon dioxide.
9. C: The amine N atom coordinates one alkyl halide molecule to form a dialkylammonium halide species, which then loses HX to form a secondary amine. The secondary amine undergoes the same coordination-elimination sequence to form a tertiary amine from the intermediate trialkylammonium halide species. The tertiary amine coordinates the alkyl halide to form a tetraalkylammonium halide, but cannot eliminate HX. All three secondary and tertiary amines and quaternary ammonium salts are produced in the reaction.
10.C: The α,β-unsaturated ketone system is polarized by the carbonyl group through its extended π bond system. The carbonyl C atom and the β C atom are both subject to attack by a nucleophile. The Michael addition takes advantage of this to add a carbon nucleophile at the β position. This forms a new C-C bond and is irreversible because of that. The actual product of the reaction upon completion is an enol, but this immediately rearranges to the ketone form. The "Michelson-Morley experiment" was an exercise to measure the speed of light. "Michaelson reaction" and "Mitchell addition" are made-up terms and have no meaning.
Last Updated: 04/12/2014