Which of the following lanthanoid ions is diamagnetic?
$$\left( {{\text{At}}{\text{.}}\,{\text{no}}{\text{.}}\,Ce = 58,Sm = 62,} \right.$$ $$\left. {Eu = 63,Yb = 70} \right)$$
A.
$$C{e^{2 + }}$$
B.
$$S{m^{2 + }}$$
C.
$$E{u^{2 + }}$$
D.
$$Y{b^{2 + }}$$
Answer :
$$Y{b^{2 + }}$$
Solution :
Lanthanoid ion with no unpaired electron is diamagnetic in nature.
$$C{e_{58}} = \left[ {Xe} \right]4{f^2}5{d^0}6{s^2}$$
$$C{e^{2 + }} = \left[ {Xe} \right]4{f^2}$$ (two unpaired electrons)
$$S{m_{62}} = \left[ {Xe} \right]4{f^6}5{d^0}6{s^2}$$
$$S{m^{2 + }} = \left[ {Xe} \right]4{f^6}$$ (six unpaired electrons)
$$E{u_{63}} = \left[ {Xe} \right]4{f^7}5{d^0}6{s^2}$$
$$E{u^{2 + }} = \left[ {Xe} \right]4{f^7}$$ (seven unpaired electrons)
$$Y{b_{70}} = \left[ {Xe} \right]4{f^{14}}5{d^0}6{s^2}$$
$$Y{b^{2 + }} = \left[ {Xe} \right]4{f^{14}}$$ (no unpaired electrons)
Because of the absence of unpaired electrons, $$Y{b^{2 + }}$$ is diamagnetic.
Releted MCQ Question on Inorganic Chemistry >> D and F Block Elements
Releted Question 1
When same amount of zinc is treated separately with excess of sulphuric acid and excess of sodium hydroxide, the ratio of volume of hydrogen evolved is