Blueprint MCAT
Practice Full
Length Questions
and Answers
Updated 2026
Assuming the salt is sodium chloride, what is the approximate molar concentration of salt in
ocean water if the density of ocean water is 1.028 kg/L?
A) 0.026 M
B) 0.62 M
C) 0.96 M
D) 9.6 M
Question from Passage 1 (1-5) - Answer B) 0.62 M
1 L of ocean water has a mass of 1028 g, of which 3.5% is dissolved salt. The molar mass of
NaCl is approximately 58 g.
(1028 g)(0.035) ≅ (1000 g)(0.036) = 36 g NaCl
(36 g NaCl) / (58 g NaCl/mol) ≅ 60 g NaCl / 100 g NaCl/mol = 0.6 moles
0.6 moles / 1 L = 0.6 M
If a person drank a large quantity of hypersaline ocean water, the person could die because
absorption of salt into the blood will cause it to become:
A. hypotonic compared with the cytosol of the body's cells, causing osmosis of water into
the cells.
,B. hypertonic compared with the cytosol of the body's cells, causing osmosis of water into
the cells.
C. hypotonic compared with the cytosol of the body's cells, causing osmosis of water out of
the cells.
D. hypertonic compared with the cytosol of the body's cells, causing osmosis of water out of
the cells. - Answer D. hypertonic compared with the cytosol of the body's cells, causing
osmosis of water out of the cells.
Explanation: The ingested salt will be absorbed into the blood, producing a relatively
concentrated, or hypertonic, solution. Remember, NaCl does not readily diffuse through the
phospholipid bilayer. However, water can diffuse via osmosis, resulting in a flow of water out
of the cell in an attempt to reestablish isotonic solutions on both sides of the membrane.
Based on Figure 1, adding salt to water causes the boiling point of the water to:
A. increase, requiring a greater average kinetic energy of the liquid to produce a vapor
pressure equal to the external pressure.
B. increase, requiring a greater average kinetic energy of the liquid to produce a vapor
pressure that is greater than the external pressure.
C. decrease, requiring a lower average kinetic energy of the liquid to produce a vapor
pressure equal to the external pressure.
D. decrease, requiring a lower average kinetic energy of the liquid to produce a vapor
pressure that is less than the external pressure.
Look at Figure 1 - Answer A.increase, requiring a greater average kinetic energy of the liquid
to produce a vapor pressure equal to the external pressure.
Explanation: As stated in the passage, adding salt reduces the vapor pressure of the liquid.
Specifically, as the solute concentration is increased, the rate at which water molecules
escape from the liquid surface decreases. Remember that boiling point is defined as the
temperature at which the vapor pressure of a solution is equal to the atmospheric pressure.
A decrease in vapor pressure makes this point more difficult to achieve, so an increase in
kinetic energy is required. Therefore, the boiling temperature is higher
,Water is an unusual substance in that the solid is less dense than the liquid at the freezing
point, resulting in a solid form that floats on top of the liquid. Which of the following best
explains this phenomenon?
A. The bent structure of the water molecule results in a molecular dipole that maximizes the
close molecular packing structure in the solid state.
B. The bent structure of the water molecule and ratio of covalently-bonded hydrogens to
lone pairs of electrons on the oxygen atom maximizes the hydrogen bonding interactions
that occur in the solid phase, producing a hexagonal structure with large empty spaces.
C. The degree of ionization in the solid state is less than in the liquid phase.
D. The London dispersion forces of water significantly decrease in the solid phase as
compared with the liquid phase. - Answer B. The bent structure of the water molecule and
ratio of covalently-bonded hydrogens to lone pairs of electrons on the oxygen atom
maximizes the hydrogen bonding interactions that occur in the solid phase, producing a
hexagonal structure with large empty spaces.
Explanation: For most substances, the liquid becomes more dense as the average kinetic
energy (temperature) decreases, and the solid is more dense than the liquid due to close-
packing solid-state structures. Thus, the solid is at the bottom of the liquid. Water, however,
has a maximum density at 4oC, above its freezing point of 0°C. Below 4oC water molecules
move apart from one another to maximize hydrogen-bonding interactions, so the density
decreases. The result is that ice floats on the liquid.
What is the chemical formula of gypsum?
A. CaSO3
B. CaSO4
C. Ca2SO3
D. Ca2SO4 - Answer B. CaSO4
Explanation: The passage states that gypsum is calcium sulfate, an ionic compound. Calcium
cation always has a +2 charge, while sulfate anion carries a -2 charge. These ions can thus be
combined in a 1:1 ratio to balance charge, leading to an overall formula of CaSO4.
, Which of the following are products of the decay of I-131?
A. Ionizing radiation, Xe-131, and an electron
B. Ionizing radiation, Te-131, and an electron
C. Non-ionizing radiation, Xe-131, and a positron
D. Non-ionizing radiation, Te-131, and a positron
Passage 2 (6-9) - Answer A. Ionizing radiation, Xe-131, and an electron
Explanation: Paragraph 3 mentions that the nuclei emit gamma rays, a form of
electromagnetic radiation that consists of high-energy photons. Gamma rays are a form of
ionizing radiation. The passage also states that I-131 undergoes β-minus decay. In β-minus
decay, a neutron is converted to a proton as an electron is emitted. Therefore, iodine must
be converted to an element with one additional proton, which can only be Xe.
β-minus decay is depicted below. Note that we can think of this process in two ways: either
as the emission of an electron, or as the conversion of a neutron into a proton, an electron,
and a neutrino (shown in the circle on the bottom right).
Why did the researchers choose to study pediatric, rather than adult, thyroid cancer cases?
A. Thyroid cancer is not otherwise present in children.
B. Thyroid cancer is not otherwise present in adults.
C. Children receive a higher relative dose of I-131 at the same contamination level.
D. Children receive a lower relative dose of I-131 at the same contamination level. - Answer
C. Children receive a higher relative dose of I-131 at the same contamination level.
Explanation: One reason for the use of pediatric cancer cases is that these cases are more
likely to be caused by I-131 than those in adults. Because children weigh less than adults,
the same quantity of external I-131 would result in a higher concentration of the isotope in
the body, making DNA damage and cancer more likely.
Practice Full
Length Questions
and Answers
Updated 2026
Assuming the salt is sodium chloride, what is the approximate molar concentration of salt in
ocean water if the density of ocean water is 1.028 kg/L?
A) 0.026 M
B) 0.62 M
C) 0.96 M
D) 9.6 M
Question from Passage 1 (1-5) - Answer B) 0.62 M
1 L of ocean water has a mass of 1028 g, of which 3.5% is dissolved salt. The molar mass of
NaCl is approximately 58 g.
(1028 g)(0.035) ≅ (1000 g)(0.036) = 36 g NaCl
(36 g NaCl) / (58 g NaCl/mol) ≅ 60 g NaCl / 100 g NaCl/mol = 0.6 moles
0.6 moles / 1 L = 0.6 M
If a person drank a large quantity of hypersaline ocean water, the person could die because
absorption of salt into the blood will cause it to become:
A. hypotonic compared with the cytosol of the body's cells, causing osmosis of water into
the cells.
,B. hypertonic compared with the cytosol of the body's cells, causing osmosis of water into
the cells.
C. hypotonic compared with the cytosol of the body's cells, causing osmosis of water out of
the cells.
D. hypertonic compared with the cytosol of the body's cells, causing osmosis of water out of
the cells. - Answer D. hypertonic compared with the cytosol of the body's cells, causing
osmosis of water out of the cells.
Explanation: The ingested salt will be absorbed into the blood, producing a relatively
concentrated, or hypertonic, solution. Remember, NaCl does not readily diffuse through the
phospholipid bilayer. However, water can diffuse via osmosis, resulting in a flow of water out
of the cell in an attempt to reestablish isotonic solutions on both sides of the membrane.
Based on Figure 1, adding salt to water causes the boiling point of the water to:
A. increase, requiring a greater average kinetic energy of the liquid to produce a vapor
pressure equal to the external pressure.
B. increase, requiring a greater average kinetic energy of the liquid to produce a vapor
pressure that is greater than the external pressure.
C. decrease, requiring a lower average kinetic energy of the liquid to produce a vapor
pressure equal to the external pressure.
D. decrease, requiring a lower average kinetic energy of the liquid to produce a vapor
pressure that is less than the external pressure.
Look at Figure 1 - Answer A.increase, requiring a greater average kinetic energy of the liquid
to produce a vapor pressure equal to the external pressure.
Explanation: As stated in the passage, adding salt reduces the vapor pressure of the liquid.
Specifically, as the solute concentration is increased, the rate at which water molecules
escape from the liquid surface decreases. Remember that boiling point is defined as the
temperature at which the vapor pressure of a solution is equal to the atmospheric pressure.
A decrease in vapor pressure makes this point more difficult to achieve, so an increase in
kinetic energy is required. Therefore, the boiling temperature is higher
,Water is an unusual substance in that the solid is less dense than the liquid at the freezing
point, resulting in a solid form that floats on top of the liquid. Which of the following best
explains this phenomenon?
A. The bent structure of the water molecule results in a molecular dipole that maximizes the
close molecular packing structure in the solid state.
B. The bent structure of the water molecule and ratio of covalently-bonded hydrogens to
lone pairs of electrons on the oxygen atom maximizes the hydrogen bonding interactions
that occur in the solid phase, producing a hexagonal structure with large empty spaces.
C. The degree of ionization in the solid state is less than in the liquid phase.
D. The London dispersion forces of water significantly decrease in the solid phase as
compared with the liquid phase. - Answer B. The bent structure of the water molecule and
ratio of covalently-bonded hydrogens to lone pairs of electrons on the oxygen atom
maximizes the hydrogen bonding interactions that occur in the solid phase, producing a
hexagonal structure with large empty spaces.
Explanation: For most substances, the liquid becomes more dense as the average kinetic
energy (temperature) decreases, and the solid is more dense than the liquid due to close-
packing solid-state structures. Thus, the solid is at the bottom of the liquid. Water, however,
has a maximum density at 4oC, above its freezing point of 0°C. Below 4oC water molecules
move apart from one another to maximize hydrogen-bonding interactions, so the density
decreases. The result is that ice floats on the liquid.
What is the chemical formula of gypsum?
A. CaSO3
B. CaSO4
C. Ca2SO3
D. Ca2SO4 - Answer B. CaSO4
Explanation: The passage states that gypsum is calcium sulfate, an ionic compound. Calcium
cation always has a +2 charge, while sulfate anion carries a -2 charge. These ions can thus be
combined in a 1:1 ratio to balance charge, leading to an overall formula of CaSO4.
, Which of the following are products of the decay of I-131?
A. Ionizing radiation, Xe-131, and an electron
B. Ionizing radiation, Te-131, and an electron
C. Non-ionizing radiation, Xe-131, and a positron
D. Non-ionizing radiation, Te-131, and a positron
Passage 2 (6-9) - Answer A. Ionizing radiation, Xe-131, and an electron
Explanation: Paragraph 3 mentions that the nuclei emit gamma rays, a form of
electromagnetic radiation that consists of high-energy photons. Gamma rays are a form of
ionizing radiation. The passage also states that I-131 undergoes β-minus decay. In β-minus
decay, a neutron is converted to a proton as an electron is emitted. Therefore, iodine must
be converted to an element with one additional proton, which can only be Xe.
β-minus decay is depicted below. Note that we can think of this process in two ways: either
as the emission of an electron, or as the conversion of a neutron into a proton, an electron,
and a neutrino (shown in the circle on the bottom right).
Why did the researchers choose to study pediatric, rather than adult, thyroid cancer cases?
A. Thyroid cancer is not otherwise present in children.
B. Thyroid cancer is not otherwise present in adults.
C. Children receive a higher relative dose of I-131 at the same contamination level.
D. Children receive a lower relative dose of I-131 at the same contamination level. - Answer
C. Children receive a higher relative dose of I-131 at the same contamination level.
Explanation: One reason for the use of pediatric cancer cases is that these cases are more
likely to be caused by I-131 than those in adults. Because children weigh less than adults,
the same quantity of external I-131 would result in a higher concentration of the isotope in
the body, making DNA damage and cancer more likely.
