Which one of the following has the highest number of unpaired electrons?
Correct answer: B. Mn2+
- A. Fe2+
- B. Mn2+
- C. Cr5+
- D. Zn2+
Explanation
Option A: In Fe[2],The electrons fill up 3d orbitals after 4s orbitals are filled. But when they are ionized [lose 2 electrons from 4s orbital], their electrons fill only the 3d orbitals in ground state. So Iron (II) ion will have 4 unpaired electrons.Option B: Mn has atomic number = 25, so electronic configuration ofMn+2 will be [Ar]3d54s0. Hence, it has 5 unpaired electrons.Option C: Cr5+ has 1 unpaired electron.Option D: Zn2+ has 0 unpaired d electrons
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About Transition Elements
Transition elements are identified by their partially filled d subshells in atoms or common ions. The topic covers the electronic structure of d-block elements, including the filling order of 4s and 3d orbitals, variable oxidation states and the distinction between transition elements and elements with completely filled d subshells.
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