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Classification Of Elements And Periodicity In Properties

Question
CBSEENCH11008364

Which one of the following ion has electronic configuration [Ar] 3d6?
(At. no:  Mn = 25, Fe = 26, Co = 27, Ni = 28)

  • Ni3+

  • Mn

  • Fe3+

  • Co3+

Solution

D.

Co3+

The electronic configurations of given ions are:
Ni3+ (28) = [Ar] 3d7
Mn3+ (25) = [Ar] 3d4
Fe3+ (26) = [Ar] 3d5
Co3+ (27) = [Ar] 3d6