AQA A-Level Chemistry Paper 3, 2021: Question 10
1 mark · Easy difficulty · Multiple Choice
Electron Configuration and Noble Gases This multiple-choice question tests understanding of electron configurations and how ions can achieve noble gas configurations. Students must identify which ion has a complete outer shell equivalent to that of a noble gas.
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Question text
10 Which has the electron configuration of a noble gas?
[1 mark]
A H+
B O–
C Se2–
D Zn2+
Mark scheme
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10 C 1 Se2–
How to answer it
Answer Explained: Electron Configuration of a Noble Gas
✅ Correct Answer: C) Se2−
Selenium has 34 electrons. Gaining 2 electrons makes 36 electrons, the same as krypton (Kr), a noble gas.
Selenium has 34 electrons. Gaining 2 electrons makes 36 electrons, the same as krypton (Kr), a noble gas.
[Ar] 3d10 4s2 4p6 ❌ A) H+
H+ has no electrons, so it has no electron configuration at all.
H+ has no electrons, so it has no electron configuration at all.
❌ B) O−
Oxygen with a single negative charge (9 electrons) does not reach neon’s 10-electron configuration.
Oxygen with a single negative charge (9 electrons) does not reach neon’s 10-electron configuration.
❌ D) Zn2+
Zinc has 30 electrons. Zn2+ has 28, which is not a noble gas configuration.
Zinc has 30 electrons. Zn2+ has 28, which is not a noble gas configuration.
Topics
Physical Chemistry · 3.1.1 Atomic Structure
Question and mark scheme from the AQA A-Level Chemistry examination, Paper 3, 2021. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.