UNE General Chemistry II Midterm Test Bank:
Weeks 1–7 Complete Practice Questions
with Verified Answers – Graded A+ Study
Guide.
WEEK 1: Intermolecular Forces & Properties of Liquids
Question 1: Which of the following will have the highest vapor pressure?
A) 0.1 M NaCl in water
B) 0.5 M NaCl in water
C) 1.0 M NaCl in water
D) 2.0 M NaCl in water
Correct Answer: A) 0.1 M NaCl in water
Explanation: Vapor pressure is a colligative property that depends on the number of solute
particles in solution. The vapor pressure of a solution is lowered by the presence of solute
particles (Raoult's Law). A 0.1 M solution has the fewest solute particles, so it experiences
the smallest vapor pressure lowering and therefore has the highest vapor pressure .
Question 2: What type of intermolecular force is present between water molecules?
A) London dispersion forces only
B) Dipole-dipole forces only
C) Hydrogen bonding
D) Ionic bonding
Correct Answer: C) Hydrogen bonding
Explanation: Water molecules exhibit hydrogen bonding, which is a particularly strong
, type of dipole-dipole interaction that occurs when hydrogen is bonded to highly
electronegative atoms like oxygen, nitrogen, or fluorine. This explains water's unusually
high boiling point and surface tension .
Question 3: An adhesive force is best described as:
A) The attraction between molecules of the same substance
B) The attraction between molecules of different substances
C) The repulsion between molecules of the same substance
D) The force that holds atoms together in a molecule
Correct Answer: B) The attraction between molecules of different substances
Explanation: Adhesive forces are intermolecular forces that attract different types of
molecules to each other. This is the opposite of cohesive forces, which are attractions
between molecules of the same substance .
Question 4: Metallic solids are composed of:
A) Atoms with nuclei in a "sea" of delocalized electrons
B) Ions held together by electrostatic forces
C) Covalently bonded atoms in a network structure
D) Individual molecules held by London dispersion forces
Correct Answer: A) Atoms with nuclei in a "sea" of delocalized electrons
Explanation: Metallic solids have a unique structure where metal cations are surrounded
by a "sea" of delocalized electrons that can move freely throughout the solid. This electron
sea model explains the characteristic properties of metals, including electrical conductivity,
malleability, and ductility .
Question 5: Which intermolecular force is present in all molecules regardless of
polarity?
, A) Hydrogen bonding
B) Dipole-dipole forces
C) London dispersion forces
D) Ion-dipole forces
Correct Answer: C) London dispersion forces
Explanation: London dispersion forces (also called induced dipole-induced dipole forces)
are the weakest type of intermolecular force but are present in all molecules. They arise
from temporary fluctuations in electron distribution that create instantaneous dipoles .
Question 6: Acetonitrile (CH₃CN) evaporates very quickly at room temperature and feels
cold when evaporating. If ΔHvap for acetonitrile is 34.2 kJ/mol, how much heat is
removed when 1.0 mole of acetonitrile evaporates?
A) 34.2 J
B) 34.2 kJ
C) 342 kJ
D) 3.42 kJ
Correct Answer: B) 34.2 kJ
Explanation: The enthalpy of vaporization (ΔHvap) is the amount of heat required to
vaporize one mole of a liquid at constant temperature. For acetonitrile, ΔHvap = 34.2
kJ/mol, so vaporizing 1.0 mole requires (and removes from the surroundings) 34.2 kJ of
heat. This is why the liquid feels cold upon evaporation—heat is absorbed from the skin .
Question 7: Which of the following correctly ranks the strength of intermolecular forces
from strongest to weakest?
A) Hydrogen bonding > dipole-dipole > London dispersion
B) Dipole-dipole > hydrogen bonding > London dispersion
C) London dispersion > dipole-dipole > hydrogen bonding
D) Hydrogen bonding > London dispersion > dipole-dipole
Correct Answer: A) Hydrogen bonding > dipole-dipole > London dispersion
Explanation: Hydrogen bonding is the strongest type of intermolecular force, followed by
, dipole-dipole interactions, with London dispersion forces being the weakest. The strength
of intermolecular forces determines physical properties such as boiling points, melting
points, and vapor pressure .
Question 8: Which substance would you expect to have the highest boiling point?
A) CH₄ (methane)
B) H₂O (water)
C) H₂S (hydrogen sulfide)
D) HCl (hydrogen chloride)
Correct Answer: B) H₂O (water)
Explanation: Water has the highest boiling point among these options due to hydrogen
bonding, which is much stronger than the dipole-dipole forces in H₂S and HCl, or the
London dispersion forces in CH₄. The strong hydrogen bonds require more energy to break
during vaporization .
Question 9: The surface tension of a liquid is due to:
A) The cohesive forces between molecules at the surface
B) The adhesive forces between molecules at the surface
C) The repulsive forces between molecules at the surface
D) The gravitational forces acting on the surface molecules
Correct Answer: A) The cohesive forces between molecules at the surface
Explanation: Surface tension arises because molecules at the surface of a liquid experience
net inward attractive forces (cohesive forces) since they have fewer neighbors to interact
with compared to molecules in the bulk. This creates a "skin" effect at the surface and
minimizes surface area .
Question 10: Which of the following would have the highest viscosity?
Weeks 1–7 Complete Practice Questions
with Verified Answers – Graded A+ Study
Guide.
WEEK 1: Intermolecular Forces & Properties of Liquids
Question 1: Which of the following will have the highest vapor pressure?
A) 0.1 M NaCl in water
B) 0.5 M NaCl in water
C) 1.0 M NaCl in water
D) 2.0 M NaCl in water
Correct Answer: A) 0.1 M NaCl in water
Explanation: Vapor pressure is a colligative property that depends on the number of solute
particles in solution. The vapor pressure of a solution is lowered by the presence of solute
particles (Raoult's Law). A 0.1 M solution has the fewest solute particles, so it experiences
the smallest vapor pressure lowering and therefore has the highest vapor pressure .
Question 2: What type of intermolecular force is present between water molecules?
A) London dispersion forces only
B) Dipole-dipole forces only
C) Hydrogen bonding
D) Ionic bonding
Correct Answer: C) Hydrogen bonding
Explanation: Water molecules exhibit hydrogen bonding, which is a particularly strong
, type of dipole-dipole interaction that occurs when hydrogen is bonded to highly
electronegative atoms like oxygen, nitrogen, or fluorine. This explains water's unusually
high boiling point and surface tension .
Question 3: An adhesive force is best described as:
A) The attraction between molecules of the same substance
B) The attraction between molecules of different substances
C) The repulsion between molecules of the same substance
D) The force that holds atoms together in a molecule
Correct Answer: B) The attraction between molecules of different substances
Explanation: Adhesive forces are intermolecular forces that attract different types of
molecules to each other. This is the opposite of cohesive forces, which are attractions
between molecules of the same substance .
Question 4: Metallic solids are composed of:
A) Atoms with nuclei in a "sea" of delocalized electrons
B) Ions held together by electrostatic forces
C) Covalently bonded atoms in a network structure
D) Individual molecules held by London dispersion forces
Correct Answer: A) Atoms with nuclei in a "sea" of delocalized electrons
Explanation: Metallic solids have a unique structure where metal cations are surrounded
by a "sea" of delocalized electrons that can move freely throughout the solid. This electron
sea model explains the characteristic properties of metals, including electrical conductivity,
malleability, and ductility .
Question 5: Which intermolecular force is present in all molecules regardless of
polarity?
, A) Hydrogen bonding
B) Dipole-dipole forces
C) London dispersion forces
D) Ion-dipole forces
Correct Answer: C) London dispersion forces
Explanation: London dispersion forces (also called induced dipole-induced dipole forces)
are the weakest type of intermolecular force but are present in all molecules. They arise
from temporary fluctuations in electron distribution that create instantaneous dipoles .
Question 6: Acetonitrile (CH₃CN) evaporates very quickly at room temperature and feels
cold when evaporating. If ΔHvap for acetonitrile is 34.2 kJ/mol, how much heat is
removed when 1.0 mole of acetonitrile evaporates?
A) 34.2 J
B) 34.2 kJ
C) 342 kJ
D) 3.42 kJ
Correct Answer: B) 34.2 kJ
Explanation: The enthalpy of vaporization (ΔHvap) is the amount of heat required to
vaporize one mole of a liquid at constant temperature. For acetonitrile, ΔHvap = 34.2
kJ/mol, so vaporizing 1.0 mole requires (and removes from the surroundings) 34.2 kJ of
heat. This is why the liquid feels cold upon evaporation—heat is absorbed from the skin .
Question 7: Which of the following correctly ranks the strength of intermolecular forces
from strongest to weakest?
A) Hydrogen bonding > dipole-dipole > London dispersion
B) Dipole-dipole > hydrogen bonding > London dispersion
C) London dispersion > dipole-dipole > hydrogen bonding
D) Hydrogen bonding > London dispersion > dipole-dipole
Correct Answer: A) Hydrogen bonding > dipole-dipole > London dispersion
Explanation: Hydrogen bonding is the strongest type of intermolecular force, followed by
, dipole-dipole interactions, with London dispersion forces being the weakest. The strength
of intermolecular forces determines physical properties such as boiling points, melting
points, and vapor pressure .
Question 8: Which substance would you expect to have the highest boiling point?
A) CH₄ (methane)
B) H₂O (water)
C) H₂S (hydrogen sulfide)
D) HCl (hydrogen chloride)
Correct Answer: B) H₂O (water)
Explanation: Water has the highest boiling point among these options due to hydrogen
bonding, which is much stronger than the dipole-dipole forces in H₂S and HCl, or the
London dispersion forces in CH₄. The strong hydrogen bonds require more energy to break
during vaporization .
Question 9: The surface tension of a liquid is due to:
A) The cohesive forces between molecules at the surface
B) The adhesive forces between molecules at the surface
C) The repulsive forces between molecules at the surface
D) The gravitational forces acting on the surface molecules
Correct Answer: A) The cohesive forces between molecules at the surface
Explanation: Surface tension arises because molecules at the surface of a liquid experience
net inward attractive forces (cohesive forces) since they have fewer neighbors to interact
with compared to molecules in the bulk. This creates a "skin" effect at the surface and
minimizes surface area .
Question 10: Which of the following would have the highest viscosity?
