Which of the following lanthanoid ions is diamagnetic? (At. No. Ce=58, Sm=62, Eu=63, Yb=70)

Options

A. `Eu^(2+)`
B. `Yb^(2+)`
C. `Ce^(2+)`
D. `Sm^(2+)`

Answer

B

Explanation

`Eu(Z=63)implies4f^76s^2,Eu^(2+)=4f^7`
it has 7 unpaired electrons so it is paramagnetic.
b. `Yb(Z=70)implies4f^(14)6s^2,Yb^(2+)=4f^(14)`
It has no unpaired electrons so it is diamagnetic.
d. `Sm(Z=62)implies4f^66s^2,Sm^(2+)=4f^6`
it has 6 unpaired electrons so it is paramagnetic.