CHEM 210 Module 2 Exam (Portage Learning
2025/2026) — 30 High-Level Practice Questions
with 100% Correct Answers
1. Which set of quantum numbers (n, l, m , mₛ) is valid for an electron in a ground-state
sulfur atom?
A. 3, 3, −1, +½
B. 2, 1, −2, −½
C. 3, 2, 0, +½
D. 4, 0, 1, −½
Correct Answer: C
Explanation: l must be ≤ n−1; m ranges from −l to +l. Only option C satisfies all rules (n = 3, l
= 2, m = 0, mₛ = ±½).
2. Arrange the following species in order of increasing atomic radius: Mg²⁺, Na⁺, Ne, F⁻.
A. Mg²⁺ < Na⁺ < Ne < F⁻
B. F⁻ < Ne < Na⁺ < Mg²⁺
, C. Na⁺ < Mg²⁺ < F⁻ < Ne
D. Ne < F⁻ < Na⁺ < Mg²⁺
Correct Answer: A
Explanation: All are isoelectronic (10 e⁻). Radius increases as nuclear charge decreases: Mg²⁺ (12
p⁺) smallest → F⁻ (9 p⁺) largest.
3. What is the maximum number of electrons that can occupy the n = 4 energy level?
A. 16
B. 24
C. 32
D. 48
Correct Answer: C
Explanation: 2n² = 2(4)² = 32 electrons.
4. Which element has the highest first ionization energy?
A. Li
B. Be
2025/2026) — 30 High-Level Practice Questions
with 100% Correct Answers
1. Which set of quantum numbers (n, l, m , mₛ) is valid for an electron in a ground-state
sulfur atom?
A. 3, 3, −1, +½
B. 2, 1, −2, −½
C. 3, 2, 0, +½
D. 4, 0, 1, −½
Correct Answer: C
Explanation: l must be ≤ n−1; m ranges from −l to +l. Only option C satisfies all rules (n = 3, l
= 2, m = 0, mₛ = ±½).
2. Arrange the following species in order of increasing atomic radius: Mg²⁺, Na⁺, Ne, F⁻.
A. Mg²⁺ < Na⁺ < Ne < F⁻
B. F⁻ < Ne < Na⁺ < Mg²⁺
, C. Na⁺ < Mg²⁺ < F⁻ < Ne
D. Ne < F⁻ < Na⁺ < Mg²⁺
Correct Answer: A
Explanation: All are isoelectronic (10 e⁻). Radius increases as nuclear charge decreases: Mg²⁺ (12
p⁺) smallest → F⁻ (9 p⁺) largest.
3. What is the maximum number of electrons that can occupy the n = 4 energy level?
A. 16
B. 24
C. 32
D. 48
Correct Answer: C
Explanation: 2n² = 2(4)² = 32 electrons.
4. Which element has the highest first ionization energy?
A. Li
B. Be
