WGU D444 Adult Health 1 Objective
Assessment | OA V1 and V2 – Questions
and Answers | 2026 Update | 100%
Correct.
SECTION 1: ATOMIC STRUCTURE & PERIODICITY
, 1. Which element has the electron configuration 1s² 2s² 2p⁶ 3s² 3p⁵?
A) Fluorine (F)
B) Chlorine (Cl)
C) Sulfur (S)
D) Argon (Ar)
Correct Answer: B
Rationale: The electron configuration sums to 17 electrons (1s²=2, 2s²=2, 2p⁶=8, 3s²=2,
3p⁵=5; total = 2+2+8+2+5=17). The element with atomic number 17 is chlorine (Cl).
Fluorine is atomic number 9, sulfur is 16, and argon is 18 .
2. Which of the following periodic trends is CORRECT?
A) Atomic radius increases from left to right across a period
B) Ionization energy increases from left to right across a period
C) Electronegativity decreases from left to right across a period
D) Atomic radius increases from top to bottom in a group
Correct Answer: B
Rationale: Ionization energy (the energy required to remove an electron) generally
increases from left to right across a period due to increasing nuclear charge and
decreasing atomic radius. Atomic radius decreases left to right and increases down a
group. Electronegativity increases left to right .
, 3. What is the maximum number of electrons that can occupy the third energy
level (n=3)?
A) 2
B) 8
C) 18
D) 32
Correct Answer: C
Rationale: The maximum number of electrons in an energy level is given by 2n². For n=3:
2 × 3² = 2 × 9 = 18 electrons. These electrons are distributed among the 3s, 3p, and 3d
subshells .
4. Which isotope is used in carbon dating?
A) Carbon-12
B) Carbon-13
C) Carbon-14
D) Carbon-15
Correct Answer: C
Rationale: Carbon-14 (¹⁴C) is a radioactive isotope used in radiocarbon dating. It is
produced in the upper atmosphere and incorporated into living organisms. After death, the
¹⁴C decays at a known rate (half-life ~5,730 years), allowing age determination of organic
materials .
5. Which of the following elements has the smallest atomic radius?
Assessment | OA V1 and V2 – Questions
and Answers | 2026 Update | 100%
Correct.
SECTION 1: ATOMIC STRUCTURE & PERIODICITY
, 1. Which element has the electron configuration 1s² 2s² 2p⁶ 3s² 3p⁵?
A) Fluorine (F)
B) Chlorine (Cl)
C) Sulfur (S)
D) Argon (Ar)
Correct Answer: B
Rationale: The electron configuration sums to 17 electrons (1s²=2, 2s²=2, 2p⁶=8, 3s²=2,
3p⁵=5; total = 2+2+8+2+5=17). The element with atomic number 17 is chlorine (Cl).
Fluorine is atomic number 9, sulfur is 16, and argon is 18 .
2. Which of the following periodic trends is CORRECT?
A) Atomic radius increases from left to right across a period
B) Ionization energy increases from left to right across a period
C) Electronegativity decreases from left to right across a period
D) Atomic radius increases from top to bottom in a group
Correct Answer: B
Rationale: Ionization energy (the energy required to remove an electron) generally
increases from left to right across a period due to increasing nuclear charge and
decreasing atomic radius. Atomic radius decreases left to right and increases down a
group. Electronegativity increases left to right .
, 3. What is the maximum number of electrons that can occupy the third energy
level (n=3)?
A) 2
B) 8
C) 18
D) 32
Correct Answer: C
Rationale: The maximum number of electrons in an energy level is given by 2n². For n=3:
2 × 3² = 2 × 9 = 18 electrons. These electrons are distributed among the 3s, 3p, and 3d
subshells .
4. Which isotope is used in carbon dating?
A) Carbon-12
B) Carbon-13
C) Carbon-14
D) Carbon-15
Correct Answer: C
Rationale: Carbon-14 (¹⁴C) is a radioactive isotope used in radiocarbon dating. It is
produced in the upper atmosphere and incorporated into living organisms. After death, the
¹⁴C decays at a known rate (half-life ~5,730 years), allowing age determination of organic
materials .
5. Which of the following elements has the smallest atomic radius?
