# In context of the lanthanoids, which of the following statement is not correct ? Option 1) There is a gradual decrease in the radii of the members with increasing atomic number in the series. Option 2) All the members exhibit +3 oxidation state Option 3) Because  of similar properties the separation of lanthanoids is not easy. Option 4) Availability of $4f$ electrons results in the formation of compounds in +4 state for all the members of the series.

D Divya Saini

As we learnt in

Electronic configuration -

The lanthanoid follow the  4f1-14  5d0-1  6s2  configuration (common configuration)with some exception due to full filled half filled electronic configuration.

- wherein

$eg\rightarrow 4f^{1}5d^{1}6s^{2}$

$4f$ electrons of lanthanoids did not participate in bond formation.

Option 1)

There is a gradual decrease in the radii of the members with increasing atomic number in the series.

This option is incorrect.

Option 2)

All the members exhibit +3 oxidation state

This option is incorrect.

Option 3)

Because  of similar properties the separation of lanthanoids is not easy.

This option is incorrect.

Option 4)

Availability of $4f$ electrons results in the formation of compounds in +4 state for all the members of the series.

This option is correct.

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