AAMC MCAT- FLASHCARDS
QUESTIONS & ANSWERS
(Chemistry)
Consider the reaction rate described by the following equation.
Rate = k[A]^m*[B]^n
The overall reaction is said to be SECOND ORDER when:
A. k is constant, m=0, and n=0
B. k is constant, m=1, and n=1
C. k is constant, m=2, and n=2
D. k=2, and m and n are variable - ANSWERSB. k is constant, m=1, and n=1
*The reaction is second order if the sum of the exponents "m" and "n" equals 2. In rate
laws, k is the rate constant. The sum of the exponents equals 2 when "m" equals 1 and
"n" equals 1. Thus, B is the correct answer
(Chemistry)
A student plans to add HCl to a solution containing Pb(NO3) (aq). To determine how
much Pb2+ will precipitate from solution when the HCl is added, the student needs to
know which of the following?
A. Ka for HCl
B. Ka for HNO3
C. Ksp for PbCl2
D. Keq for the reaction Pb2+ + 2e- <---> Pb - ANSWERSC. Ksp for PbCl2
*To determine how much Pb2+ will precipitate, the student must know the solubility of
PbCl2, which is related to the solubility product constant Ksp of PbCl2. Thus, C is the
best answer.
(Chemistry)
,Which of the following electron configurations of nitrogen is the most stable?
A. 1s^2, 2s^1, 2p^4
B. 1s^2, 2s^2, 2p^3
C. 1s^1, 2s^2, 2p^4
D. 1s^2, 2s^2, 2p^2, 3s^1 - ANSWERSB. 1s^2, 2s^2, 2p^3
*The atomic number of nitrogen is 7. The electrons will begin to fill the lower energy
level first; consequently, the 1s level will fill first with two electrons, followed by the 2s
with two electrons, and then the 2p level with the last three electrons. The resulting
electron configuration is 1s^2, 2s^2, 2p^3. Thus, B is the best answer.
(Chemistry)
When a weak acid (HA) is titrated with sodium hydroxide in the presence of an indicator
(HIn), the pH at which a color change is observed depends on the:
A. final concentration of HA
B. final concentration of HIn
C. initial concentration of HA
D. pka of HIn - ANSWERSD. pka of HIn (indicator)
*The indicator will change color over a specific pH range. The range at which the color
change takes place depends on the point at which HIn is converted to In- , and this
depends of the pKa of the indicator which is answer D.
(Chemistry)
Approximately how many moles of Al^3+ are reduced when 0.1 faraday of a charge
passes through a cell during the production of Al? (Note: Assume there is excess Al^3+
available and that Al^3+ is reduced to Al metal only)
A. 0.033 mol
B. 0.050 mol
C. 0.067 mol
D. 0.10 mol - ANSWERSA faraday is equal to one mole of electric charge. Because
each aluminum ion gains 3 electrons, 0.1 faraday of charge will reduce 0.1/3 moles of
aluminum, or 0.033 moles of aluminum
(Chemistry)
The following reaction occurs spontaneously.
Cd(s) + 2 H+(aq) --> Cd^2+(aq) + H2(g)
Which of the following has the highest electron affinity?
,A. Cd(s)
B. H+(aq)
C. Cd^2+(aq)
D. H2(g) - ANSWERSB. H+(aq)
*The reaction equation shows the reduction of H+ by Cd. Because H+ accepts the
electron readily from Cd, it can be determined that H+ has the highest electron affinity.
(Chemistry)
Phosphorus appears directly below nitrogen in the periodic table. The boiling point of
ammonia, NH3, is higher than the boiling point of phosphine, PH3, under standard
conditions. Which of the following statements best explains the difference in the boiling
points o these two compounds?
A. Ammonia is a weaker base than phosphine.
B. N-H bond is weaker than the P-H bond
C. High molecular weight compounds generally have lower boiling points.
D. Ammonia forms stronger intermolecular hydrogen bonds than phosphine. -
ANSWERSD. Ammonia forms stronger intermolecular hydrogen bonds than phosphine.
*A substance boils when enough heat has been supplied to overcome the
intermolecular forces. The fact that ammonia has a higher boiling point than phosphine
indicates that ammonia requires more heat to overcome the intermolecular than does
phosphine and therefore the intermolecular forces in ammonia are stronger than those
in phosphine.
(Chemistry)
A gas that occupies 10 L at 1 atm and 25 C will occupy what volume at 500 atm and 25
C?
A. Exactly 0.020 L
B. Somewhat more than 0.02 L because of the space occupied by the individual gas
molecules
C. Somewhat more than 0.02 L because of the repulsions between the individual gas
molecules
D. Somewhat more than 0.02 L because of the increased number of collisions with the
sides of the container - ANSWERSB. Somewhat more than 0.02 L because of the
space occupied by the individual gas molecules
*The ideal gas law makes the assumption that molecules have no volume. This
assumption is adequate when the gas is at 1 atm, but when the pressure is increased to
500 atm the volume of the gas molecules in no longer negligible.
, (Chemistry)
If the quantity of gas remains unchanged while its temperature increases, the volume of
the gas will:
A. always increase, because volume is directly proportional to temperature.
B. always decrease, because volume is inversely proportional to temperature.
C. increase if pressure remains constant.
D. decrease if pressure remains constant. - ANSWERSC. increase if pressure remains
constant.
*The ideal gas law states PV = nRT. If "n" (the quantity of gas) is constant and "T"
(temperature) increases, then "PV" (pressure x volume) will increase. If pressure
remains constant, then volume must increase. Thus, answer C is the best answer.
(Chemistry)
Which of the following statements best characterizes a material that is a good insulator
but a poor conductor?
A. The material contains no electrons.
B. The magnitude of the electric field inside the material is always equal to zero.
C. The atoms in the material can easily move from one lattice site to another.
D. Electrons in the material cannot easily move from one atom to another. -
ANSWERSD. Electrons in the material cannot easily move from one atom to another.
*In insulators, the valence electrons are tightly bound to their atoms, and it takes a great
amount of energy to free them from their atomic energy levels. Thus, D is the best
answer.
(Chemistry)
A student measures the mass and volume of four objects.
Object / Mass (g) / Volume (cm^3)
A / 1..5
B / 3..75
C / 4..00
D / 6..50
Which object has the highest density? - ANSWERSC. 4.5g/1.00cc = 4.5g/cc
*Density = mass / volume. The densities of the four objects are:
A. (1.5/0.50) = 3.0 g/cc
B. (3.0/0.75) = 4.0 g/cc
QUESTIONS & ANSWERS
(Chemistry)
Consider the reaction rate described by the following equation.
Rate = k[A]^m*[B]^n
The overall reaction is said to be SECOND ORDER when:
A. k is constant, m=0, and n=0
B. k is constant, m=1, and n=1
C. k is constant, m=2, and n=2
D. k=2, and m and n are variable - ANSWERSB. k is constant, m=1, and n=1
*The reaction is second order if the sum of the exponents "m" and "n" equals 2. In rate
laws, k is the rate constant. The sum of the exponents equals 2 when "m" equals 1 and
"n" equals 1. Thus, B is the correct answer
(Chemistry)
A student plans to add HCl to a solution containing Pb(NO3) (aq). To determine how
much Pb2+ will precipitate from solution when the HCl is added, the student needs to
know which of the following?
A. Ka for HCl
B. Ka for HNO3
C. Ksp for PbCl2
D. Keq for the reaction Pb2+ + 2e- <---> Pb - ANSWERSC. Ksp for PbCl2
*To determine how much Pb2+ will precipitate, the student must know the solubility of
PbCl2, which is related to the solubility product constant Ksp of PbCl2. Thus, C is the
best answer.
(Chemistry)
,Which of the following electron configurations of nitrogen is the most stable?
A. 1s^2, 2s^1, 2p^4
B. 1s^2, 2s^2, 2p^3
C. 1s^1, 2s^2, 2p^4
D. 1s^2, 2s^2, 2p^2, 3s^1 - ANSWERSB. 1s^2, 2s^2, 2p^3
*The atomic number of nitrogen is 7. The electrons will begin to fill the lower energy
level first; consequently, the 1s level will fill first with two electrons, followed by the 2s
with two electrons, and then the 2p level with the last three electrons. The resulting
electron configuration is 1s^2, 2s^2, 2p^3. Thus, B is the best answer.
(Chemistry)
When a weak acid (HA) is titrated with sodium hydroxide in the presence of an indicator
(HIn), the pH at which a color change is observed depends on the:
A. final concentration of HA
B. final concentration of HIn
C. initial concentration of HA
D. pka of HIn - ANSWERSD. pka of HIn (indicator)
*The indicator will change color over a specific pH range. The range at which the color
change takes place depends on the point at which HIn is converted to In- , and this
depends of the pKa of the indicator which is answer D.
(Chemistry)
Approximately how many moles of Al^3+ are reduced when 0.1 faraday of a charge
passes through a cell during the production of Al? (Note: Assume there is excess Al^3+
available and that Al^3+ is reduced to Al metal only)
A. 0.033 mol
B. 0.050 mol
C. 0.067 mol
D. 0.10 mol - ANSWERSA faraday is equal to one mole of electric charge. Because
each aluminum ion gains 3 electrons, 0.1 faraday of charge will reduce 0.1/3 moles of
aluminum, or 0.033 moles of aluminum
(Chemistry)
The following reaction occurs spontaneously.
Cd(s) + 2 H+(aq) --> Cd^2+(aq) + H2(g)
Which of the following has the highest electron affinity?
,A. Cd(s)
B. H+(aq)
C. Cd^2+(aq)
D. H2(g) - ANSWERSB. H+(aq)
*The reaction equation shows the reduction of H+ by Cd. Because H+ accepts the
electron readily from Cd, it can be determined that H+ has the highest electron affinity.
(Chemistry)
Phosphorus appears directly below nitrogen in the periodic table. The boiling point of
ammonia, NH3, is higher than the boiling point of phosphine, PH3, under standard
conditions. Which of the following statements best explains the difference in the boiling
points o these two compounds?
A. Ammonia is a weaker base than phosphine.
B. N-H bond is weaker than the P-H bond
C. High molecular weight compounds generally have lower boiling points.
D. Ammonia forms stronger intermolecular hydrogen bonds than phosphine. -
ANSWERSD. Ammonia forms stronger intermolecular hydrogen bonds than phosphine.
*A substance boils when enough heat has been supplied to overcome the
intermolecular forces. The fact that ammonia has a higher boiling point than phosphine
indicates that ammonia requires more heat to overcome the intermolecular than does
phosphine and therefore the intermolecular forces in ammonia are stronger than those
in phosphine.
(Chemistry)
A gas that occupies 10 L at 1 atm and 25 C will occupy what volume at 500 atm and 25
C?
A. Exactly 0.020 L
B. Somewhat more than 0.02 L because of the space occupied by the individual gas
molecules
C. Somewhat more than 0.02 L because of the repulsions between the individual gas
molecules
D. Somewhat more than 0.02 L because of the increased number of collisions with the
sides of the container - ANSWERSB. Somewhat more than 0.02 L because of the
space occupied by the individual gas molecules
*The ideal gas law makes the assumption that molecules have no volume. This
assumption is adequate when the gas is at 1 atm, but when the pressure is increased to
500 atm the volume of the gas molecules in no longer negligible.
, (Chemistry)
If the quantity of gas remains unchanged while its temperature increases, the volume of
the gas will:
A. always increase, because volume is directly proportional to temperature.
B. always decrease, because volume is inversely proportional to temperature.
C. increase if pressure remains constant.
D. decrease if pressure remains constant. - ANSWERSC. increase if pressure remains
constant.
*The ideal gas law states PV = nRT. If "n" (the quantity of gas) is constant and "T"
(temperature) increases, then "PV" (pressure x volume) will increase. If pressure
remains constant, then volume must increase. Thus, answer C is the best answer.
(Chemistry)
Which of the following statements best characterizes a material that is a good insulator
but a poor conductor?
A. The material contains no electrons.
B. The magnitude of the electric field inside the material is always equal to zero.
C. The atoms in the material can easily move from one lattice site to another.
D. Electrons in the material cannot easily move from one atom to another. -
ANSWERSD. Electrons in the material cannot easily move from one atom to another.
*In insulators, the valence electrons are tightly bound to their atoms, and it takes a great
amount of energy to free them from their atomic energy levels. Thus, D is the best
answer.
(Chemistry)
A student measures the mass and volume of four objects.
Object / Mass (g) / Volume (cm^3)
A / 1..5
B / 3..75
C / 4..00
D / 6..50
Which object has the highest density? - ANSWERSC. 4.5g/1.00cc = 4.5g/cc
*Density = mass / volume. The densities of the four objects are:
A. (1.5/0.50) = 3.0 g/cc
B. (3.0/0.75) = 4.0 g/cc
