Which of the following has the maximum number of unpaired d electrons?
Correct answer: D. Fe2+
- A. Mg2+
- B. Ti3+
- C. V3+
- D. Fe2+
Explanation
The correct answer is Fe2+. The electron configuration for Fe2+ is [Ar] 3d6, with the 3d subshell holding six electrons: four of these are unpaired due to Hund's rule, which states that electrons fill degenerate orbitals singly first. Mg2+ lacks d electrons entirely, Ti3+ has only one unpaired d electron ([Ar] 3d1), and V3+ has two unpaired d electrons ([Ar] 3d2).
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About Electronic Structure of d-Block Elements
The electronic structure of d-block elements covers the filling of the (n-1)d and ns orbitals, general electronic configurations, and the exceptions shown by chromium and copper. It explains how partially filled d orbitals produce variable oxidation states, coloured ions, magnetic behaviour and complex formation, while distinguishing transition elements from elements with completely filled d subshells.
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