What is the oxidation number of $Pt$ in $[Pt(C_2H_4)Cl_4]^-$?

Which of the following is the correct $IUPAC$ name for a complex compound?

Write the formulas for the following coordination compounds:
$(a)$ Tetraammineaquachloridocobalt $(III)$ chloride
$(b)$ Potassium tetrahydroxidozincate $(II)$
$(c)$ Potassium trioxalatoaluminate $(III)$
$(d)$ Dichloridobis(ethane$-1,2-$diamine)cobalt $(III)$
$(e)$ Tetracarbonylnickel $(0)$

The $IUPAC$ name of $[Co(NH_3)_3(NO_2)_3]$ is

The oxidation number and coordination number of cobalt in $K[Co(CO)_4]$ are

The $IUPAC$ name of $[Cr(NH_3)_6]^{3+}$ is