(A) Oxidation number of Ni in `Ni(C0)_(4)` is taken zero. (R ) The oxidation numb

(A) Oxidation number of Ni in `Ni(C0)_(4)` is taken zero. (R ) The oxidation numb

(A) Oxidation number of Ni in `Ni(C0)_(4)` is taken zero. (R ) The oxidation number of CO has been taken to be zero.