1
CHEM 210 - FINAL EXAM 2026/2027 | 100 VERIFIED
Q&A | DETAILED RATIONALES | NGN-ALIGNED |
PASS GUARANTEED – A+ GRADED
SECTION I: ATOMIC STRUCTURE AND PERIODICITY - Questions 1-10
Q1: Quantum numbers
The student is reviewing quantum numbers. Which set of quantum numbers is NOT allowed?
A. n=2, l=1, ml=0, ms=+1/2
B. n=3, l=2, ml=-2, ms=-1/2
C. n=2, l=2, ml=1, ms=+1/2
D. n=4, l=0, ml=0, ms=-1/2
Correct Answer: C
Rationale: The azimuthal quantum number l must be less than n. For n=2, l can only be 0 or 1.
l=2 is not allowed. [100% CORRECT]
Q2: Electron configuration of ions
The student is reviewing electron configurations. What is the electron configuration of Fe²⁺
(Z=26)?
A. [Ar] 3d⁶
B. [Ar] 3d⁴ 4s²
C. [Ar] 3d⁵ 4s¹
D. [Ar] 3d⁶ 4s²
Correct Answer: A
Rationale: Fe is [Ar] 3d⁶ 4s². When forming Fe²⁺, electrons are removed from the 4s orbital first,
giving [Ar] 3d⁶. [100% CORRECT]
Q3: Periodic trend: electron affinity
The student is reviewing periodic trends. Which element has the most negative electron
affinity?
A. F
B. Cl
C. Br
D. I
,2
Correct Answer: B
Rationale: Chlorine has a more negative electron affinity than fluorine because fluorine's small
size causes greater electron-electron repulsion in the compact 2p orbital. [100% CORRECT]
Q4: Effective nuclear charge
The student is reviewing periodic trends. How does effective nuclear charge (Zeff) change across
a period?
A. Increases
B. Decreases
C. Remains constant
D. Randomly fluctuates
Correct Answer: A
Rationale: Across a period, protons are added to the nucleus while electrons enter the same
shell, so shielding changes little. Zeff increases, pulling electrons closer. [100% CORRECT]
Q5: Atomic radius of ions
The student is reviewing ionic radii. Which ion is larger than its neutral atom?
A. Na⁺
B. Mg²⁺
C. Cl⁻
D. Al³⁺
Correct Answer: C
Rationale: Anions are larger than their neutral atoms because added electrons increase
repulsion. Cl⁻ is larger than Cl. Cations are smaller. [100% CORRECT]
Q6: Magnetic properties
The student is reviewing magnetism. Which ion is paramagnetic?
A. Zn²⁺
B. Cu²⁺
C. Ca²⁺
D. Sc³⁺
Correct Answer: B
Rationale: Cu²⁺ has the configuration [Ar] 3d⁹, with one unpaired electron, making it
paramagnetic. Zn²⁺ (3d¹⁰), Ca²⁺, and Sc³⁺ are diamagnetic. [100% CORRECT]
Q7: Ionization energy anomalies
The student is reviewing ionization energy. Why is the first ionization energy of oxygen lower
, 3
than that of nitrogen?
A. Oxygen has a larger atomic radius
B. Oxygen has electron pairing repulsion in the 2p orbital
C. Nitrogen has a higher nuclear charge
D. Oxygen has a filled 2p subshell
Correct Answer: B
Rationale: Nitrogen has a half-filled 2p³ configuration (stable). Oxygen has 2p⁴, so one orbital is
doubly occupied, causing electron-electron repulsion that makes it easier to remove an
electron. [100% CORRECT]
Q8: Quantum mechanical model
The student is reviewing orbitals. What does the square of the wavefunction (ψ²) represent?
A. Probability density of finding an electron
B. Energy of the electron
C. Spin of the electron
D. Angular momentum
Correct Answer: A
Rationale: ψ² gives the probability density of finding an electron at a given point in space. [100%
CORRECT]
Q9: Photoelectric effect
The student is reviewing the photoelectric effect. What does the kinetic energy of an ejected
electron depend on?
A. Intensity of light
B. Frequency of light
C. Number of photons
D. Distance from source
Correct Answer: B
Rationale: KE = hν − φ, so kinetic energy depends on the frequency of light and the work
function. Intensity affects the number of electrons, not their energy. [100% CORRECT]
Q10: de Broglie wavelength
The student is reviewing wave-particle duality. What is the de Broglie wavelength of an electron
with mass 9.11×10⁻³¹ kg moving at 1.0×10⁶ m/s?
A. 7.27×10⁻¹⁰ m
B. 7.27×10⁻¹¹ m
C. 7.27×10⁻⁹ m
D. 7.27×10⁻¹² m
CHEM 210 - FINAL EXAM 2026/2027 | 100 VERIFIED
Q&A | DETAILED RATIONALES | NGN-ALIGNED |
PASS GUARANTEED – A+ GRADED
SECTION I: ATOMIC STRUCTURE AND PERIODICITY - Questions 1-10
Q1: Quantum numbers
The student is reviewing quantum numbers. Which set of quantum numbers is NOT allowed?
A. n=2, l=1, ml=0, ms=+1/2
B. n=3, l=2, ml=-2, ms=-1/2
C. n=2, l=2, ml=1, ms=+1/2
D. n=4, l=0, ml=0, ms=-1/2
Correct Answer: C
Rationale: The azimuthal quantum number l must be less than n. For n=2, l can only be 0 or 1.
l=2 is not allowed. [100% CORRECT]
Q2: Electron configuration of ions
The student is reviewing electron configurations. What is the electron configuration of Fe²⁺
(Z=26)?
A. [Ar] 3d⁶
B. [Ar] 3d⁴ 4s²
C. [Ar] 3d⁵ 4s¹
D. [Ar] 3d⁶ 4s²
Correct Answer: A
Rationale: Fe is [Ar] 3d⁶ 4s². When forming Fe²⁺, electrons are removed from the 4s orbital first,
giving [Ar] 3d⁶. [100% CORRECT]
Q3: Periodic trend: electron affinity
The student is reviewing periodic trends. Which element has the most negative electron
affinity?
A. F
B. Cl
C. Br
D. I
,2
Correct Answer: B
Rationale: Chlorine has a more negative electron affinity than fluorine because fluorine's small
size causes greater electron-electron repulsion in the compact 2p orbital. [100% CORRECT]
Q4: Effective nuclear charge
The student is reviewing periodic trends. How does effective nuclear charge (Zeff) change across
a period?
A. Increases
B. Decreases
C. Remains constant
D. Randomly fluctuates
Correct Answer: A
Rationale: Across a period, protons are added to the nucleus while electrons enter the same
shell, so shielding changes little. Zeff increases, pulling electrons closer. [100% CORRECT]
Q5: Atomic radius of ions
The student is reviewing ionic radii. Which ion is larger than its neutral atom?
A. Na⁺
B. Mg²⁺
C. Cl⁻
D. Al³⁺
Correct Answer: C
Rationale: Anions are larger than their neutral atoms because added electrons increase
repulsion. Cl⁻ is larger than Cl. Cations are smaller. [100% CORRECT]
Q6: Magnetic properties
The student is reviewing magnetism. Which ion is paramagnetic?
A. Zn²⁺
B. Cu²⁺
C. Ca²⁺
D. Sc³⁺
Correct Answer: B
Rationale: Cu²⁺ has the configuration [Ar] 3d⁹, with one unpaired electron, making it
paramagnetic. Zn²⁺ (3d¹⁰), Ca²⁺, and Sc³⁺ are diamagnetic. [100% CORRECT]
Q7: Ionization energy anomalies
The student is reviewing ionization energy. Why is the first ionization energy of oxygen lower
, 3
than that of nitrogen?
A. Oxygen has a larger atomic radius
B. Oxygen has electron pairing repulsion in the 2p orbital
C. Nitrogen has a higher nuclear charge
D. Oxygen has a filled 2p subshell
Correct Answer: B
Rationale: Nitrogen has a half-filled 2p³ configuration (stable). Oxygen has 2p⁴, so one orbital is
doubly occupied, causing electron-electron repulsion that makes it easier to remove an
electron. [100% CORRECT]
Q8: Quantum mechanical model
The student is reviewing orbitals. What does the square of the wavefunction (ψ²) represent?
A. Probability density of finding an electron
B. Energy of the electron
C. Spin of the electron
D. Angular momentum
Correct Answer: A
Rationale: ψ² gives the probability density of finding an electron at a given point in space. [100%
CORRECT]
Q9: Photoelectric effect
The student is reviewing the photoelectric effect. What does the kinetic energy of an ejected
electron depend on?
A. Intensity of light
B. Frequency of light
C. Number of photons
D. Distance from source
Correct Answer: B
Rationale: KE = hν − φ, so kinetic energy depends on the frequency of light and the work
function. Intensity affects the number of electrons, not their energy. [100% CORRECT]
Q10: de Broglie wavelength
The student is reviewing wave-particle duality. What is the de Broglie wavelength of an electron
with mass 9.11×10⁻³¹ kg moving at 1.0×10⁶ m/s?
A. 7.27×10⁻¹⁰ m
B. 7.27×10⁻¹¹ m
C. 7.27×10⁻⁹ m
D. 7.27×10⁻¹² m
