Question

Which of the following lanthanoid ions is diamagnetic? (Atomic number of `Ce=58,Sm=62,Eu=63,Yb=70`]
A. `Cu^(2+)`
B. `Sm^(2+)`
C. `Eu^(2+)`
D. `Yb^(2+)`

Answer 1

Correct Answer - D
Lanthanoid ion with no unpaired electron is diamagnetic in nature. `58Ce=[Xe]4f^(2),5d^(0),6s^(2)`
`Ce^(2+)=[Xe]4f^(2)` ("Two unpaire electrons")
`._(62)Sm=[Xe]4f^(6),5d^(0)6s^(2)`
`Sm^(2+)=4f^(6)implies6," unpaired electrons"`
`._(63)Eu=[Xe]4f^(7)5d^(0)6s^(2)`
`Eu^(2+)=4f^(7)implies7,"unpaired electrons"`
`Yb=[Xe]4f^(14)6s^(2),Yb^(2+)=4f^(14)`
No unpaired electron hence diamagnetic.