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
arsenic atom?
A. 3, 3, −2, +½
B. 4, 1, 0, −½
C. 4, 2, +3, +½
D. 3, 2, −1, −½
Correct Answer: B
Short explanation: l must be < n; |m | ≤ l. Only 4, 1, 0, −½ satisfies all rules for a 4p electron in
As.
2. The first ionization energy of aluminum is 578 kJ mol⁻¹. How much energy (kJ) is
required to ionize 5.40 g of Al atoms?
A. 115
B. 173
C. 289
D. 347
Correct Answer: A
Calculation: n = 5.40 g / 26.98 g mol⁻¹ = 0.200 mol; E = 0.200 mol × 578 kJ mol⁻¹ = 115.6 kJ ≈
115 kJ.
, 3. Arrange the following ions in order of increasing ionic radius: Mg²⁺, Na⁺, F⁻, O²⁻.
A. Mg²⁺ < Na⁺ < F⁻ < O²⁻
B. O²⁻ < F⁻ < Na⁺ < Mg²⁺
C. Na⁺ < Mg²⁺ < F⁻ < O²⁻
D. Mg²⁺ < O²⁻ < F⁻ < Na⁺
Correct Answer: A
Trend: isoelectronic with Ne; smaller Zeff → larger radius. Mg²⁺ (12 p) holds electrons tightest;
O²⁻ (8 p) is largest.
4. How many nodes (total) are present in a 4f orbital?
A. 3
B. 4
C. 5
D. 6
Correct Answer: B
Total nodes = n − 1 = 4 − 1 = 3 radial + 1 angular = 4.
5. Which element has the largest atomic radius in its period?
A. K
B. Ca
C. Br
D. Kr
Correct Answer: A
Down-group and left-side trend: K (period 4, group 1) is farthest left.
6. The electron configuration of Cr³⁺ is
A. [Ar] 3d³
B. [Ar] 3d² 4s¹
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
arsenic atom?
A. 3, 3, −2, +½
B. 4, 1, 0, −½
C. 4, 2, +3, +½
D. 3, 2, −1, −½
Correct Answer: B
Short explanation: l must be < n; |m | ≤ l. Only 4, 1, 0, −½ satisfies all rules for a 4p electron in
As.
2. The first ionization energy of aluminum is 578 kJ mol⁻¹. How much energy (kJ) is
required to ionize 5.40 g of Al atoms?
A. 115
B. 173
C. 289
D. 347
Correct Answer: A
Calculation: n = 5.40 g / 26.98 g mol⁻¹ = 0.200 mol; E = 0.200 mol × 578 kJ mol⁻¹ = 115.6 kJ ≈
115 kJ.
, 3. Arrange the following ions in order of increasing ionic radius: Mg²⁺, Na⁺, F⁻, O²⁻.
A. Mg²⁺ < Na⁺ < F⁻ < O²⁻
B. O²⁻ < F⁻ < Na⁺ < Mg²⁺
C. Na⁺ < Mg²⁺ < F⁻ < O²⁻
D. Mg²⁺ < O²⁻ < F⁻ < Na⁺
Correct Answer: A
Trend: isoelectronic with Ne; smaller Zeff → larger radius. Mg²⁺ (12 p) holds electrons tightest;
O²⁻ (8 p) is largest.
4. How many nodes (total) are present in a 4f orbital?
A. 3
B. 4
C. 5
D. 6
Correct Answer: B
Total nodes = n − 1 = 4 − 1 = 3 radial + 1 angular = 4.
5. Which element has the largest atomic radius in its period?
A. K
B. Ca
C. Br
D. Kr
Correct Answer: A
Down-group and left-side trend: K (period 4, group 1) is farthest left.
6. The electron configuration of Cr³⁺ is
A. [Ar] 3d³
B. [Ar] 3d² 4s¹
