Question
Which one of the following statements related to lanthanons is incorrect?
A.
Europium shows + 2 oxidation state
B.
The basicity decreases as the ionic radius decreases from $$Pr$$ to $$Lu$$
C.
All the lanthanons are much more reactive than aluminium
D.
$$Ce (+4)$$ solution are widely used as oxidising agent in volumetric analysis
Answer :
All the lanthanons are much more reactive than aluminium
Solution :
$$Eu\left( {63} \right) = 4{f^7} \cdot 5{d^0},6{s^2},E{u^{2 + }} = 4{f^7}$$
In lanthanoids series, ionic radius decreases and covalent character increases, thus basicity decreases. Lanthanons are less reactive than aluminium due to high ionisation potential. The reason for this high ionisation potential is lanthanoid contraction. $$C{e^{4 + }}$$ is a good oxidising agent, it is easily converted to $$C{e^{3 + }}$$