The pair of ions having same electronic configuration is __________.
o The electronic configuration of Fe3+ - 1s2 2s2 2p6 3s2 3p63d5
(Z of Fe = 26, that means [Ar] 3d6 4s2 electronic configuration and Fe3+ having 3 electrons less. Ar stands for Argon having 1s2 2s2 2p6 3s2 3p6)
o Mn2+ also having a [Ar] 3d5 configuration makes Fe3+, Mn2+ isoelectronic species; having same electronic configuration. ( Z of Mn = 25 , that means [Ar] 3d5 4s2 electronic configuration and Mn2+ having 2 electrons less. Ar stands for Argon having 1s2 2s2 2p6 3s2 3p6)
Other 3 options:(i)Cr3+(Z= 24 ,[Ar] 3d3),Fe3+ (Z=26[Ar ]3d5)
(iii)Fe3+(Z=26[Ar]3d5,Co3+ (Z= 27 ,[Ar] 3d6) and
(iv) Sc3+ ( Z=21,[ Ar]3d0 ) , Cr3+ (Z=24 ,[Ar] 3d3),cannotbe considered to have same electronic configurations.