An atom's electron configuration defies the Aufbau principle for stability. Which metal exhibits this?
Q1. An atom's electron configuration defies the Aufbau principle for stability. Which metal exhibits this?
Answer: Copper
Explanation: Copper's [Ar]3d¹⁰4s¹ (option A) is more stable than the predicted [Ar]3d⁹4s². Iron (option B) follows Aufbau.