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Question
Q149) Which of the following has maximum number of unpaired electrons




SOLUTION

For Cu, Z=29 Thus Cu2+ number of electrons=29-2=27
Electron configuration [Ar]3d9 thus one unpaired
For Cr, Z=24 , Thus Cr3+ , number of electrons=24-3=21
Electron configuration [Ar]3d3 thus Three unpaired electrons
For Ni, Z=28 , Thus Ni2+ , number of electrons=28-3=26
Electron configuration [Ar]3d8 thus two unpaired electrons
For Fe, Z=26, Thus Fe3+ , number of electrons=26-3=23
Electron configuration [Ar]3d5 thus Five unpaired electrons
Answer: (d)