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Which one of the following statements related to lanthanons is incorrect?
A
All the lanthanons 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.
Explanation
Lanthanoids are not all more reactive than aluminium.
Detailed Solution
Lanthanons are less reactive than aluminium due to high ionisation potential (lanthanide contraction).
$Ce^{4+}$ is a good oxidising agent and is easily converted into $Ce^{3+}$.
Eu (63) = $[Xe]4f^75d^06s^2$; $Eu^{2+} = 4f^7$
In the lanthanoid series from Ce to Lu, ionic radius decreases regularly and covalent character increases, so the basic character of hydroxides decreases.
$Ce^{4+}$ is a good oxidising agent and is easily converted into $Ce^{3+}$.
Eu (63) = $[Xe]4f^75d^06s^2$; $Eu^{2+} = 4f^7$
In the lanthanoid series from Ce to Lu, ionic radius decreases regularly and covalent character increases, so the basic character of hydroxides decreases.