Answer:
Iron have unpaired 3d electrons.
Step-by-step explanation:
It can be explained by observing electronic configuration of the given elements.
- Zn- 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s².
- Fe- 1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁶ 4s².
- Ca- 1s² 2s² 2p⁶ 3s² 3p⁶ 4s².
- Ge- 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p².
Where, Zn is zinc,
Fe is iron,
Ca is calcium and
Ge is germanium.
- 3d orbital have 5 sub shells which means it can carry 10 electrons.
- On observing electronic configuration of Zn, 3d orbital have 10 electrons and hence it is completely filled and no unpaired electrons in 3d orbital.
- On observing electronic configuration of Fe, 3d orbital have 6 electrons and hence have unpaired electrons (as five electrons will fill five sub shell of d orbital and the 6th electron will enter in first sub shell and get paired and the other 4 sub shell will have only one electron and hence will be unpaired).
- On observing electronic configuration of Ca it does not have 3d orbital and hence it is out of the case.
- On observing electronic configuration of Ge 3d orbital is completely filled with 10 electrons and hence is completely paired.
Result: Fe have unpaired 3d electrons.