Question

Which one of the followng statements related to lanthanides is incorrect ?

• A. All the lanthanoids are much more reactive than aluminium
• B. Ce(+4) solutions are widely used as oxidizing agent in volumetric analysis
  
• C. Europium shows +2 oxidation state
• D. The basicity decreases as the ionic radius decreases from Pr to Lu.

Answer 1

The correct option is A All the lanthanoids are much more reactive than aluminium

(1) It cannot be said for all lanthanides, since on going from left to right, because of the poor shielding effect, the reactivity changes. While the elements of the series on the left side are quite reactive, the ones on the right hand side are not that reactive.

(2) $C{e}^{+4}$ is good oxidising agent and easily converts into $C{e}^{+3}$

(3) $Eu\left(63\right)=4f^{7}5d^{0}6s^2,E{u}^{+2}=4f^7$

(4) In lanthanoids series from 'Ce' to 'Lu', ionic radius regularly decreases and covalent character increases, basic
character of hydroxide decreases