CHEM134 Midterm Practice Exam Set
Exam Practice Questions And Correct
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1. A 0.250 mol sample of calcium carbonate is completely decomposed
according to the equation CaCO₃(s) → CaO(s) + CO₂(g). What mass of
calcium oxide is produced?
A. 10.0 g
B. 14.0 g
C. 14.0 g
D. 28.0 g
Rationale: One mole of CaCO₃ produces one mole of CaO. The molar mass
of CaO is approximately 56.1 g/mol, so 0.250 mol × 56.1 g/mol ≈ 14.0 g.
2. Which quantum number determines the orientation of an orbital in
space?
A. Principal quantum number (n)
B. Azimuthal quantum number (ℓ)
C. Magnetic quantum number (mℓ)
D. Spin quantum number (ms)
,Rationale: The magnetic quantum number specifies the orientation of an
orbital within a subshell relative to an external magnetic field.
3. Which element has the highest first ionization energy?
A. Sodium
B. Magnesium
C. Aluminum
D. Neon
Rationale: Ionization energy generally increases across a period and
decreases down a group. Neon has a filled valence shell and requires the
most energy to remove an electron.
4. Which compound exhibits predominantly ionic bonding?
A. CH₄
B. CO₂
C. NH₃
D. NaCl
Rationale: Sodium transfers an electron to chlorine, forming oppositely
charged ions held together by electrostatic attraction.
5. Which molecular geometry corresponds to a molecule with four
bonding pairs and no lone pairs on the central atom?
A. Trigonal planar
B. Bent
C. Tetrahedral
D. Trigonal pyramidal
Rationale: According to VSEPR theory, four electron domains with no lone
pairs arrange themselves in a tetrahedral geometry.
6. What is the oxidation number of sulfur in H₂SO₄?
A. +4
B. +6
, C. +2
D. –2
Rationale: Hydrogen is +1 and oxygen is –2. Solving 2(+1) + x + 4(–2) = 0
gives sulfur an oxidation state of +6.
7. Which gas law states that pressure is inversely proportional to volume
at constant temperature?
A. Charles's law
B. Gay-Lussac's law
C. Avogadro's law
D. Boyle's law
Rationale: Boyle's law describes the inverse relationship between pressure
and volume for a fixed amount of gas at constant temperature.
8. At STP, one mole of an ideal gas occupies approximately:
A. 11.2 L
B. 22.4 L
C. 24.5 L
D. 44.8 L
Rationale: Under standard temperature and pressure, one mole of an ideal
gas occupies approximately 22.4 liters.
9. Which intermolecular force is strongest?
A. London dispersion forces
B. Dipole-dipole forces
C. Hydrogen bonding
D. Induced dipole interactions
Rationale: Hydrogen bonding is a particularly strong form of dipole-dipole
attraction involving hydrogen bonded to N, O, or F.
Exam Practice Questions And Correct
Answers (Verified Answers) Plus
Rationale 2026 Q&A| Instant Download
1. A 0.250 mol sample of calcium carbonate is completely decomposed
according to the equation CaCO₃(s) → CaO(s) + CO₂(g). What mass of
calcium oxide is produced?
A. 10.0 g
B. 14.0 g
C. 14.0 g
D. 28.0 g
Rationale: One mole of CaCO₃ produces one mole of CaO. The molar mass
of CaO is approximately 56.1 g/mol, so 0.250 mol × 56.1 g/mol ≈ 14.0 g.
2. Which quantum number determines the orientation of an orbital in
space?
A. Principal quantum number (n)
B. Azimuthal quantum number (ℓ)
C. Magnetic quantum number (mℓ)
D. Spin quantum number (ms)
,Rationale: The magnetic quantum number specifies the orientation of an
orbital within a subshell relative to an external magnetic field.
3. Which element has the highest first ionization energy?
A. Sodium
B. Magnesium
C. Aluminum
D. Neon
Rationale: Ionization energy generally increases across a period and
decreases down a group. Neon has a filled valence shell and requires the
most energy to remove an electron.
4. Which compound exhibits predominantly ionic bonding?
A. CH₄
B. CO₂
C. NH₃
D. NaCl
Rationale: Sodium transfers an electron to chlorine, forming oppositely
charged ions held together by electrostatic attraction.
5. Which molecular geometry corresponds to a molecule with four
bonding pairs and no lone pairs on the central atom?
A. Trigonal planar
B. Bent
C. Tetrahedral
D. Trigonal pyramidal
Rationale: According to VSEPR theory, four electron domains with no lone
pairs arrange themselves in a tetrahedral geometry.
6. What is the oxidation number of sulfur in H₂SO₄?
A. +4
B. +6
, C. +2
D. –2
Rationale: Hydrogen is +1 and oxygen is –2. Solving 2(+1) + x + 4(–2) = 0
gives sulfur an oxidation state of +6.
7. Which gas law states that pressure is inversely proportional to volume
at constant temperature?
A. Charles's law
B. Gay-Lussac's law
C. Avogadro's law
D. Boyle's law
Rationale: Boyle's law describes the inverse relationship between pressure
and volume for a fixed amount of gas at constant temperature.
8. At STP, one mole of an ideal gas occupies approximately:
A. 11.2 L
B. 22.4 L
C. 24.5 L
D. 44.8 L
Rationale: Under standard temperature and pressure, one mole of an ideal
gas occupies approximately 22.4 liters.
9. Which intermolecular force is strongest?
A. London dispersion forces
B. Dipole-dipole forces
C. Hydrogen bonding
D. Induced dipole interactions
Rationale: Hydrogen bonding is a particularly strong form of dipole-dipole
attraction involving hydrogen bonded to N, O, or F.
