UNE GENERAL CHEMISTRY II MIDTERM
ACTUAL EXAM300 Unique Multiple Choice
Questions with Detailed Rationales LATEST
UPDATE
SECTION A: INTERMOLECULAR FORCES & PHASE CHANGES (Questions
1–45)
Question 1
A hydrogen bond is characterized by:
A) The attraction of temporary dipoles produced by random asymmetries in
electron motion
B) The electrostatic attraction between permanent dipoles in any polar molecule
C) The highly concentrated partial charge between an H atom and F, O, or N
atoms
D) The covalent sharing of electrons between two atoms in a molecule
Answer: C
Rationale: A hydrogen bond is a special type of dipoledipole interaction that
occurs when a hydrogen atom is bonded to a highly electronegative atom (F, O, or
N). The partial positive charge on H is strongly attracted to the partial negative
charge on F, O, or N of another molecule.
1
,Question 2
Which of the following will have the strongest dipoledipole attractions?
A) NCl₃
B) CCl₄
C) BCl₃
D) Cl₂
Answer: A
Rationale: NCl₃ is asymmetrical and has a significant dipole moment. CCl₄ and Cl₂
are nonpolar, and BCl₃ is trigonal planar and nonpolar. Nitrogen is more
electronegative than boron, making NCl₃ more polar.
Question 3
A cohesive force is:
A) The result of intermolecular forces that attract identical molecules
B) The result of intermolecular forces that attract different molecules together
C) The result of covalent interactions between atoms in a molecule
D) Always stronger than an adhesive force
Answer: A
2
,Rationale: Cohesive forces are intermolecular attractions between molecules of the
same substance. These forces are responsible for surface tension and the tendency
of liquids to form droplets. Adhesive forces, in contrast, attract different molecules
together.
Question 4
Which intermolecular force is present in all molecules?
A) Hydrogen bonding
B) Dipoledipole interactions
C) London dispersion forces
D) Ionic bonding
Answer: C
Rationale: London dispersion forces (LDFs) are present in all molecules due to
temporary fluctuations in electron distribution. They are the only intermolecular
force in nonpolar molecules and are always present alongside other forces in polar
molecules.
Question 5
Which substance would you expect to have the highest boiling point?
A) CH₄
3
, B) SiH₄
C) GeH₄
D) SnH₄
Answer: D
Rationale: All these compounds are nonpolar and only exhibit London dispersion
forces. The strength of London dispersion forces increases with molecular size and
molar mass. SnH₄ has the largest molar mass, thus the strongest dispersion forces
and highest boiling point.
Question 6
Which of the following liquids would have the highest viscosity?
A) CH₃CH₂OH
B) CH₃CH₂CH₂CH₂CH₂CH₂OH
C) CH₃CH₂CH₂CH₂OH
D) CH₃OH
Answer: B
Rationale: Viscosity increases with molecular size and the strength of
intermolecular forces. All these alcohols can hydrogen bond, but longer
hydrocarbon chains lead to stronger London dispersion forces. Hexanol
(CH₃CH₂CH₂CH₂CH₂CH₂OH) has the longest chain and therefore the highest
viscosity.
4
ACTUAL EXAM300 Unique Multiple Choice
Questions with Detailed Rationales LATEST
UPDATE
SECTION A: INTERMOLECULAR FORCES & PHASE CHANGES (Questions
1–45)
Question 1
A hydrogen bond is characterized by:
A) The attraction of temporary dipoles produced by random asymmetries in
electron motion
B) The electrostatic attraction between permanent dipoles in any polar molecule
C) The highly concentrated partial charge between an H atom and F, O, or N
atoms
D) The covalent sharing of electrons between two atoms in a molecule
Answer: C
Rationale: A hydrogen bond is a special type of dipoledipole interaction that
occurs when a hydrogen atom is bonded to a highly electronegative atom (F, O, or
N). The partial positive charge on H is strongly attracted to the partial negative
charge on F, O, or N of another molecule.
1
,Question 2
Which of the following will have the strongest dipoledipole attractions?
A) NCl₃
B) CCl₄
C) BCl₃
D) Cl₂
Answer: A
Rationale: NCl₃ is asymmetrical and has a significant dipole moment. CCl₄ and Cl₂
are nonpolar, and BCl₃ is trigonal planar and nonpolar. Nitrogen is more
electronegative than boron, making NCl₃ more polar.
Question 3
A cohesive force is:
A) The result of intermolecular forces that attract identical molecules
B) The result of intermolecular forces that attract different molecules together
C) The result of covalent interactions between atoms in a molecule
D) Always stronger than an adhesive force
Answer: A
2
,Rationale: Cohesive forces are intermolecular attractions between molecules of the
same substance. These forces are responsible for surface tension and the tendency
of liquids to form droplets. Adhesive forces, in contrast, attract different molecules
together.
Question 4
Which intermolecular force is present in all molecules?
A) Hydrogen bonding
B) Dipoledipole interactions
C) London dispersion forces
D) Ionic bonding
Answer: C
Rationale: London dispersion forces (LDFs) are present in all molecules due to
temporary fluctuations in electron distribution. They are the only intermolecular
force in nonpolar molecules and are always present alongside other forces in polar
molecules.
Question 5
Which substance would you expect to have the highest boiling point?
A) CH₄
3
, B) SiH₄
C) GeH₄
D) SnH₄
Answer: D
Rationale: All these compounds are nonpolar and only exhibit London dispersion
forces. The strength of London dispersion forces increases with molecular size and
molar mass. SnH₄ has the largest molar mass, thus the strongest dispersion forces
and highest boiling point.
Question 6
Which of the following liquids would have the highest viscosity?
A) CH₃CH₂OH
B) CH₃CH₂CH₂CH₂CH₂CH₂OH
C) CH₃CH₂CH₂CH₂OH
D) CH₃OH
Answer: B
Rationale: Viscosity increases with molecular size and the strength of
intermolecular forces. All these alcohols can hydrogen bond, but longer
hydrocarbon chains lead to stronger London dispersion forces. Hexanol
(CH₃CH₂CH₂CH₂CH₂CH₂OH) has the longest chain and therefore the highest
viscosity.
4
