MEDIUMMCQ SINGLEJEE Mains ChemistryInorganic Chemistryd and f Block elementsPrevious Year Questions
The electronic configurations of Eu (Atomic No. 63), Gd (Atomic No. 64) and Tb (Atomic No. 65) are (NEET-I 2016)
A.The basicity decreases as the ionic radius decreases
B.All the lanthanons are much more reactive than✓ Correct
C.Ce (+4) solutions are widely used as oxidizing agent
D.Europium shows +2 oxidation state.
Explanation
On moving left to right of the lanthanoids series, from Pr to Lu, due to the lanthanoid contraction, the ionic radius decreases in a regular manner and the covalent character increases. This is the reason why the basic character of hydroxides decreases from Pr to Lu. Ce4+can be considered as a very good oxidizing agent, and it can easily accept one electron to reach the stable oxidation state of lanthanoids which is +3. Thus, it can be used in the volumetric analysis as an oxidizing agent. The electronic configuration of Europium can be given as: 7 0 2 2+ 7 0 0 Eu 63 :4f 5d 6s Eu (Xe):4f 5
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