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Question 600212
JEE Chemistry · Medium

Atomic Structure: Exception MCQ

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ExceptionMediumQuestion 600212

Question

The electronic configuration of Cu (Z=29) is:
  1. A
    [Ar] 3d⁹ 4s²
  2. B
    [Ar] 3d¹⁰ 4s¹
    Correct
  3. C
    [Ar] 3d⁸ 4s²4p¹
  4. D
    [Ar] 4s² 3d⁹

Correct answer

[Ar] 3d¹⁰ 4s¹

Explanation

Cu adopts [Ar] 3d¹⁰ 4s¹ (not 3d⁹ 4s²) because a completely filled d subshell is extra stable. This is a key exception.

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