Electrons in a paramagnetic compound are

Which of the following is true for $[Fe(CN)_6]^{3-}$ and $[FeF_6]^{3-}$?

The number of geometrical isomers of a planar complex $M_{abcd}$ is

Which of the following is a pair of ionization isomers?

Among the species given below,the total number of diamagnetic species is. . . . . $H$ atom,$NO_2$ monomer,$O_2^{-}$ (superoxide),dimeric sulphur in vapour phase,$Mn_3O_4$,$(NH_4)_2[FeCl_4]$,$(NH_4)_2[NiCl_4]$,$K_2MnO_4$,$K_2CrO_4$

What is the reason for the deviation between the experimental and theoretical values of magnetic moment?