The calculated spin-only magnetic moments (BM) of the anionic and cationic species of [Fe(H_2O)_6]₂ and [Fe(CN)₆], respectively, are:

Correct option is A. 4.9 and 0
Solution:- (C) 0 and 4.9
Complex is [Fe(H₂O)₆]₂ [Fe(CN)₆]
Complex ion Configuration No. of unpaired electrons Magnetic moment
[Fe(H₂O)₆]²⁺ t₂g⁴ e₂g² 4 4.9 BM
[Fe(CN)₆]⁴⁻ t₂g⁶ e₂g⁰ 0 0