JEE Main20209 Jan 2020Morning ShiftChemistryd and f Block ElementsActual
The electronic configurations of bivalent europium and trivalent cerium are: (atomic number: X e = 54 , C e = 58 , E u = 63)
Options
- AX e 4 f 2 and X e 4 f 7
- BX e 4 f 7 and X e 4 f 1
- CX e 4 f 7 6 s 2 and X e 4 f 2 6 s 2
- DX e 4 f 4 and X e 4 f 9
Correct answer
B. X e 4 f 7 and X e 4 f 1
Step-by-step solution
Electronic configuration of Ce   and   Eu in ground state are following: Ce = Xe   4 f 1   5 d 1   6 s 2 Eu = Xe   4 f 7   6 s 2 Trivalent cerium means cerium loss three electrons and obtain + 3 charge and bivalent Europium means Europium loss two electrons and obtain + 2 charge, so their electronic configurations are following E u 2 + : X e 4 f 7 C e 3 + : X e 4 f 1