In which of the following coordination compounds is the central metal ion in the zero oxidation state?

The $IUPAC$ name of $K_4[Fe(CN)_6]$ is

Using $IUPAC$ norms,write the systematic names of the following:
$(i)$ $[Co(NH_3)_6]Cl_3$
$(ii)$ $[Pt(NH_3)_2Cl(NH_2CH_3)]Cl$
$(iii)$ $[Ti(H_2O)_6]^{3+}$
$(iv)$ $[Co(NH_3)_4Cl(NO_2)]Cl$
$(v)$ $[Mn(H_2O)_6]^{2+}$
$(vi)$ $[NiCl_4]^{2-}$
$(vii)$ $[Ni(NH_3)_6]Cl_2$
$(viii)$ $[Co(en)_3]^{3+}$
$(ix)$ $[Ni(CO)_4]$

The $IUPAC$ name of $Na_3[Co(ONO)_6]$ is .....

What is the oxidation number of nickel in $Ni(CO)_4$?

The $IUPAC$ name of the Wilkinson's catalyst $[RhCl(PPh_3)_3]$ is