CHEM 210 Module 2 Exam (Portage Learning 2025/2026) — 30 High-Level Questions with 100% Correct Answers

CHEM 210 Module 2 Exam (Portage Learning
2025/2026) — 30 High-Level Questions with
100% Correct Answers

1.​ Which quantum-number set (n, l, m , mₛ) is allowed for an electron in a
ground-state arsenic atom?

A. 3, 3, –1, +½

B. 4, 2, –2, –½

C. 4, 1, +1, +½

D. 2, 2, 0, –½

Correct Answer: C

Explanation: l must be < n; m ranges from –l to +l. Only set C (4p electron) satisfies all
rules.

2.​ The first ionization energy of aluminum is lower than that of magnesium
because:

A. Al has a larger nuclear charge

B. Al’s outer electron occupies a higher-energy subshell

C. Mg has paired 3s electrons

D. Al contains more neutrons

Correct Answer: B

, Explanation: The 3p electron in Al is farther from the nucleus and less tightly held than
Mg’s 3s electron.

3.​ How many nodes (total) are present in a 4d orbital?

A. 3

B. 4

C. 5

D. 2

Correct Answer: A

Explanation: Total nodes = n – 1 = 3.

4.​ Arrange the following species in order of increasing atomic radius: P³⁻, S²⁻, Cl⁻,
Ar.

A. Ar < Cl⁻ < S²⁻ < P³⁻

B. P³⁻ < S²⁻ < Cl⁻ < Ar

C. Ar < P³⁻ < S²⁻ < Cl⁻

D. Cl⁻ < S²⁻ < P³⁻ < Ar

Correct Answer: A

Explanation: All are isoelectronic (18 e⁻); radius increases as nuclear charge decreases
(Ar has highest Z, P³⁻ lowest).

5.​ Which element has the electron configuration [Kr] 5s² 4d⁵?

A. Tc