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CSS Physical and Inorganic Chemistry P-I QUESTION #1414
Question 1
Which of the following does NOT have the ground-state configuration \(1s^2 2s^2 2p^6\)?
  • Ne
  • Na\(^+\)
  • Cl\(^-\)✔️
  • None of these
Correct Answer Explanation
Ne has 10 electrons: \(1s^2 2s^2 2p^6\) ✓. Na\(^+\) has lost one electron from Na (11e\(^-\)), giving 10e\(^-\): \(1s^2 2s^2 2p^6\) ✓. Cl\(^-\) has gained one electron from Cl (17e\(^-\)), giving 18e\(^-\): \(1s^2 2s^2 2p^6 3s^2 3p^6\) — this is the Ar configuration, NOT \(1s^2 2s^2 2p^6\). So Cl\(^-\) does NOT have this configuration.