UNE - CHEM 1011 - MIDTERM STUDY
GUIDE ACTUAL 2026 QUESTIONS AND
VERIFIED ANSWERS
1. Which of the following represents a pair of isotopes?
A) ¹⁴N and ¹⁴O
B) ¹²C and ¹⁴C
C) O₂ and O₃
D) Na⁺ and Na
,,,,answer,,,: B
Rationale: Isotopes are atoms of the same element with the same number
of protons but different numbers of neutrons. Carbon-12 and Carbon-14
both have 6 protons but differ in neutrons.
2. What is the empirical formula of a compound that is 40.0%
carbon, 6.7% hydrogen, and 53.3% oxygen by mass?
A) CHO
B) CH₂O
C) C₂H₄O₂
D) C₃H₆O₃
,,,,answer,,,: B
3. A hydrogen bond is characterized by:
A) the attraction of temporary dipoles produced by the random
asymmetries in electron motion
B) the electrostatic attraction between the 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
4. Which of the following will have the strongest dipole-dipole
attractions?
A) NCl₃
B) CCl₄
C) BCl₃
D) Cl₂
,,,,answer,,,: A
5. A cohesive force:
A) is the result of the intermolecular forces that attract identical
molecules
B) is the result of the intermolecular forces that attract different
molecules together
C) is the result of covalent interactions between atoms in a molecule
D) is always stronger than an adhesive force
,,,,answer,,,: A
6. ΔHvap is:
A) the energy change when a substance changes from the liquid
phase to the gas phase
B) the energy change when a substance changes from the solid phase to
the liquid phase
C) the energy change when a substance changes from the liquid phase to
the solid phase
D) the energy change when a substance changes from the solid phase
directly to the gas phase
,,,,answer,,,: A
, 7. A liquid in a tube will form a convex meniscus when:
A) the adhesive forces are stronger than the cohesive forces
B) the cohesive forces are stronger than the adhesive forces
C) the adhesive forces are equal to the cohesive forces
D) it's impossible to predict
,,,,answer,,,: B
8. In a phase diagram, the critical pressure represents:
A) the temperature and pressure when gas, liquid, and solid phases
coexist
B) the maximum temperature that a liquid can exist
C) the maximum pressure that a gas can exist
D) the minimum pressure that a solid can exist, regardless of
temperature
,,,,answer,,,: C
9. Molecular solids:
A) are composed of positive and negative ions held together by
electrostatic attractions
B) are composed of atoms, with nuclei in a "sea" of delocalized
electrons
C) are composed of atoms held together by a repeating network of
covalent bonds
D) are composed of neutral molecules held together by
intermolecular forces
,,,,answer,,,: D
10. The correct expression to calculate the heat required to convert
100 g of ice starting at -12 °C to liquid water at a final temperature
of 85 °C is:
A) (m × c × ΔT)ice + (n × ΔHfus) + (m × c × ΔT)water
B) (n × ΔHfus) + (m × c × ΔT)water
GUIDE ACTUAL 2026 QUESTIONS AND
VERIFIED ANSWERS
1. Which of the following represents a pair of isotopes?
A) ¹⁴N and ¹⁴O
B) ¹²C and ¹⁴C
C) O₂ and O₃
D) Na⁺ and Na
,,,,answer,,,: B
Rationale: Isotopes are atoms of the same element with the same number
of protons but different numbers of neutrons. Carbon-12 and Carbon-14
both have 6 protons but differ in neutrons.
2. What is the empirical formula of a compound that is 40.0%
carbon, 6.7% hydrogen, and 53.3% oxygen by mass?
A) CHO
B) CH₂O
C) C₂H₄O₂
D) C₃H₆O₃
,,,,answer,,,: B
3. A hydrogen bond is characterized by:
A) the attraction of temporary dipoles produced by the random
asymmetries in electron motion
B) the electrostatic attraction between the 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
4. Which of the following will have the strongest dipole-dipole
attractions?
A) NCl₃
B) CCl₄
C) BCl₃
D) Cl₂
,,,,answer,,,: A
5. A cohesive force:
A) is the result of the intermolecular forces that attract identical
molecules
B) is the result of the intermolecular forces that attract different
molecules together
C) is the result of covalent interactions between atoms in a molecule
D) is always stronger than an adhesive force
,,,,answer,,,: A
6. ΔHvap is:
A) the energy change when a substance changes from the liquid
phase to the gas phase
B) the energy change when a substance changes from the solid phase to
the liquid phase
C) the energy change when a substance changes from the liquid phase to
the solid phase
D) the energy change when a substance changes from the solid phase
directly to the gas phase
,,,,answer,,,: A
, 7. A liquid in a tube will form a convex meniscus when:
A) the adhesive forces are stronger than the cohesive forces
B) the cohesive forces are stronger than the adhesive forces
C) the adhesive forces are equal to the cohesive forces
D) it's impossible to predict
,,,,answer,,,: B
8. In a phase diagram, the critical pressure represents:
A) the temperature and pressure when gas, liquid, and solid phases
coexist
B) the maximum temperature that a liquid can exist
C) the maximum pressure that a gas can exist
D) the minimum pressure that a solid can exist, regardless of
temperature
,,,,answer,,,: C
9. Molecular solids:
A) are composed of positive and negative ions held together by
electrostatic attractions
B) are composed of atoms, with nuclei in a "sea" of delocalized
electrons
C) are composed of atoms held together by a repeating network of
covalent bonds
D) are composed of neutral molecules held together by
intermolecular forces
,,,,answer,,,: D
10. The correct expression to calculate the heat required to convert
100 g of ice starting at -12 °C to liquid water at a final temperature
of 85 °C is:
A) (m × c × ΔT)ice + (n × ΔHfus) + (m × c × ΔT)water
B) (n × ΔHfus) + (m × c × ΔT)water
