NEST2026Chemistryd and f Block Elements
Consider the following table of three lanthanoid ions X, Y, and Z and their properties. Lanthanoid Ions Properties X Diamagnetism Y Reducing agent in solution Z Empty 4f orbitals Atomic numbers of Ce, Eu, and Lu are 58 , 63 , and 71 , respectively. Given these atomic numbers, the lanthanoid ions X, Y, and Z, respectively, are:
Options
- AEu ²⁺ , Lu ³⁺ , and Ce ⁴⁺
- BLu ³⁺ , Ce ⁴⁺ , and Eu ²⁺
- CEu ²⁺ , Ce ⁴⁺ , and Lu ³⁺
- DLu ³⁺ , Eu ²⁺ , and Ce ⁴⁺
Correct answer
D. Lu ³⁺ , Eu ²⁺ , and Ce ⁴⁺
Step-by-step solution
The electronic configuration of Lu ( Z=71 ) is [ Xe ] 4f¹⁴ 5d¹ 6s² . Lu ³⁺ has the configuration [ Xe ] 4f¹⁴ . Since all electrons are paired, it is diamagnetic. Thus, X is Lu ³⁺ . The electronic configuration of Eu ( Z=63 ) is [ Xe ] 4f⁷ 6s² . Eu ²⁺ has the configuration [ Xe ] 4f⁷ . It acts as a strong reducing agent in aqueous solution because it readily oxidizes to the more stable +3 oxidation state ( Eu ³⁺ ). Thus, Y is Eu ²⁺ . The electronic configuration of Ce ( Z=58 ) is [ Xe ] 4f¹ 5d¹ 6s² . Ce ⁴⁺ has the c