In the complex acetylbromidodicarbonylbis(triethylphosphine) iron(II), the number of Fe-C bond(s) is ___________.

Among the complex ions, [Co(NH₂-CH₂-CH₂-NH₂)₂Cl₂]⁺, [CrCl₂(C₂O₄)₂]^3$$-$$, [Fe(H₂O)₄)OH)₂]⁺, [Fe(NH₃)₂(CN)₄]^$$-$$, [Co(NH₂-CH₂-CH₂-NH₂)₂(NH₃)Cl]²⁺ and [Co(NH₃)₄(H₂O)Cl]²⁺, the number of complex ions that shows cis-trans isomerism is ______________.

For the octahedral complexes of Fe³⁺ in SCN^$$-$$ (thiocyana-to-S) and in CN^$$-$$ ligand environments, the difference between the spin-only magnetic moments in Bohr magnetons (when approximated to the nearest integer) is __________.

[Atomic number Fe = 26]