Among the following lanthanoid ions, the paramagnetic ion is

Options

A. `Yb^(2+)`
B. `Eu^(2+)`
C. `Lu^(3+)`
D. `Ce^(4+)`

Answer

B

Explanation

The valence shell electronic configuration of the given ions are
`Yb=[Xe]4f^(14)6s^(2)impliesYb^(2+)=[Xe]4f^(14)implies` No unpaired `e^(-)`
`Eu=[Xe]4f^(7)6s^(2)impliesEu^(2+)=[Xe]4f^(7)implies7` unpaired `e^(-)`
`Lu=[Xe]4f^(14)5d^(1)6s^(2)impliesLu^(3+)=[Xe]4f^(14)implies` No unpaired `e^(-)`
`Ce=[Xe]4f^(1)5d^(1)6s^(2)impliesCe^(4+)=[Xe]implies` No unpaired `e^(-)`
Hence, `Eu^(2+)` is paramagnetic as it contains 7 unpaired electrons.