MCAT Question of the day

MCAT Question of the Day provides a new MCAT question once a day, every day. Questions are broken down into three categories: Physics, Biology, and Chemistry. This allows you to browse through questions in an area that you're weak in, and make them your strongest. Let's ace the MCAT. MCAT Question of the Day DAT Question of the Day DAT Practice Tests

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The pH Value Is Right

Which set of 1 Molar solutions has the correct pH values?

A. Water pH = 0; hydrochloric acid pH = 4; acetic acid pH = 7; ammonia solution pH = 10; sodium hydroxide solution pH = 14. B. Acetic acid pH = 0; hydrochloric acid pH = 4; water pH = 7; sodium hydroxide solution pH = 10; ammonia solution pH = 14. C. Sodium hydroxide solution pH = 0; ammonia solution pH = 4; water pH = 7; acetic acid pH = 10; hydrochloric acid pH = 14. D. Hydrochloric acid pH = 0; acetic acid pH = 4; water pH = 7; ammonia solution pH = 10; sodium hydroxide solution pH = 14.

To see the answer to today's question, visit the following link: http://mcatquestionoftheday.com/chemistry/the-ph-value-is-right/

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Optically Active

_____________ refers to the method by which an optically reactive reagent or catalyst is used to transform an optically inactive starting material into an optically active product.

A. Racemization B. Enantioenrichment C. Chiral chromatography D. Asymmetric induction

To see the answer to today's question, visit the following link: http://mcatquestionoftheday.com/chemistry/optically-active/

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Favored Reaction in Thermodynamics

According to the second law of thermodynamics, which of the following reactions would be favored?

A. 2H2O + O2 → 2H2O2 B. ADP + Pi → ATP C. 2H2O2 → 2H2O + O2 D. 2Na + Cl2 → 2NaCl

To see the answer to today's question, visit the following link: http://mcatquestionoftheday.com/biology/favored-reaction-in-thermodynamics/

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Know Your Thermo

Describe the reaction below:

PCl3(g) + Cl2(g) -> PCl5(g) ; Delta(Hf) = -87.9kJ/mol A. spontaneous at all temperatures. B. nonspontaneous at all temperatures. C. ΔGrxn is less than 0 at only low temperatures. D. spontaneous at only high temperatures.

To see the solution, visit the following link: http://mcatquestionoftheday.com/chemistry/know-your-thermo/

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Genetic Drift Effects

Genetic drift is the process responsible for:

A. gaining a new allele within large populations. B. gaining a new allele within sufficiently small populations. C. losing an existing allele due to emigration. D. losing an existing allele due to random sampling.

To see the solution, visit the following link: http://mcatquestionoftheday.com/biology/genetic-drift-effects/

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Rates of Consumption

During the reaction to form ammonia from nitrogen and hydrogen according to the reaction: N2(g) + 3 H2(g) <-> 2 NH3(g), ammonia was being produced at the rate of 1.50 mol.L-1.s-1. What were the respective rates of consumption of nitrogen and hydrogen at this time?

A. N2(g) 1.50 and H2(g) 1.50 mol.L-1.s-1. B. N2(g) 2.25 and H2(g) 0.75 mol.L-1.s-1. C. N2(g) 0.75 and H2(g) 2.25 mol.L-1.s-1. D. N2(g) 3.00 and H2(g) 1.00 mol.L-1.s-1.

To see the answer to today's question, visit the following link: http://mcatquestionoftheday.com/chemistry/rates-of-consumption/

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Law of Independent Assortment

Mendel’s second law, the Law of Independent Assortment, states that each trait assigned to offspring is done so without regard to any other trait assigned. In a dihybrid cross of two dogs, one that is black with a short tail and the other that is white with a long tail, the inheritance of one fur color is not dependent upon the inheritance of tail length. Assuming that black fur is dominant and a long tail is dominant and each parent is homozygous for each trait, how many offspring in the F2 generation will be white with a short tail?

A. 0 B. 1/16 C. 3/16 D. 9/16

To see the answer to today's question, visit the following link: http://mcatquestionoftheday.com/chemistry/law-of-independent-assortment/

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Bond Angles

Which of the following is closest to the bond angle of an sp2-hybridized carbon atom?

A. 180o B. 140o C. 120o D. 110o

To see the answer to today's question, visit the following link: http://mcatquestionoftheday.com/chemistry/bond-angles/

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Simple Harmonic Motion

An object undergoing simple harmonic motion is observed to have a time interval of 4 seconds between the two extremes of its displacement from equilibrium. What is the frequency of this motion?

A. 0.125 cycles/second B. 0.25 cycles/second C. 1.25 cycles/second D. 4 cycles/second

To see the answer to today's question, visit the following link: http://mcatquestionoftheday.com/physics/simple-harmonic-motion/

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Rate of Chemical Reaction

The rate at which a chemical reaction occurs is dependent on many factors. Which of the following will increase the rate of reaction?

A. Decreasing the temperature. B. Adding a catalyst. C. Decreasing the concentration of a reactant in solution. D. Decreasing the partial pressure of a reactant gas.

To see the answer to today's question, visit the following link: http://mcatquestionoftheday.com/chemistry/rate-of-chemical-reaction/

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Correct Definition of Competitive Inhibition

What is the most correct definition of competitive inhibition?

A. Another enzyme completes the same reaction and uses the available reactant. B. An inhibitor binds directly to the active site and prevents the reactant from binding. C. A metal cofactor prevents the binding of the reactant by binding at the active site. D. An inhibitor binds to the enzyme at a binding site, and prevents the enzyme from catalyzing the reaction.

To see the solution, visit the following link: http://mcatquestionoftheday.com/biology/correct-definition-of-competitive-inhibition/

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Infrared Identification

Which molecules contain an IR stretching frequency of 1680-1740 cm-1?

I. alcohols II. carboxylic acids III. nitriles IV. amides A. I and II. B. II and III. C. II and IV. D. III and IV.

To see the solution, visit the following link: http://mcatquestionoftheday.com/chemistry/infrared-identification/

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Substitute Salt

People who have high blood pressure often go on low sodium diets, in which they substitute salt (NaCl) for another compound. Which of the following would be an appropriate supplementary salt?

A. MgCl2 B. KCl C. BeCl2 D. SrCl2

To see the solution, visit the following link: http://mcatquestionoftheday.com/chemistry/substitute-salt/

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HNMR Identification

In proton NMR spectroscopy, which compounds or functional groups show a characteristic peak in the range 9-10 ppm?

A. halogenated alkanes. B. aldehydes. C. alcohols. D. aromatic compounds.

To see the solution, visit the following link: http://mcatquestionoftheday.com/chemistry/hnmr-identification/

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400 Meter Dash

An athlete runs around a 400 meter track in 60 seconds, starting and finishing at the same place. What is her speed and velocity in m/s?

A. Speed = 6.67 m/s and Velocity = zero B. Speed = zero and Velocity = 6.67 m/s C. Speed = 6.67 m/s and Velocity = 6.67 m/s 360o D. Speed = 6.67 m/s and Velocity = 6.67 m/s

To see the answer to today's question, visit the following link: http://mcatquestionoftheday.com/physics/400-meter-dash/

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Fungus Genus

What are two characteristic features of the fungus genus?

A. Monophyletic and heterotrophic. B. Polyphyletic and heterotrophic. C. Paraphyletic and heterotrophic. D. Monophyletic and autotrophic.

To see the answer to today's question, visit the following link: http://mcatquestionoftheday.com/biology/fungus-genus/

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String Cheese Theory

A hollow rubber ball, whose volume is 3 x 10-3m3 and has a mass of 1.0 kg) is held by a 1-meter-long string attached to the bottom of a large container of water. What is the tension in the string?

A. 20 N. B. 35 N. C. 40 N. D. 45 N.

To see the answer to today's question, visit the following link: http://mcatquestionoftheday.com/physics/string-cheese-theory/