The number of hydroxyl group(s) in Q is ___________.

Among the following the number of reactions that produces benzaldehyde is _________.

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 ______________.