In which of the following complexes oxidation state of metal is zero

In which of the following the oxidation number of metal ion is zero?

In which of the following compounds, the oxidation state of transition metal is zero ?

In which of the following compounds, the oxidation state of transition metal is zero ?

Which of the following complex has same oxidation state of the central metall atom in the cationic and anionic part ?

Which of the following complex has same oxidation state of the central metall atom in the cationic and anionic part ?

It which of the following compounds the oxidation state of the nickel atom is zero