Correct option is A
Solution
Oxidation state: oxidation state is the total number of electrons that an atom either gains or loses in order to form a chemical bond with another atom.
The oxidation state of Iron in Fe(CO)5
Let Oxidation state Fe be X,
then
As CO has 0 oxidation state,
X + 0(5) = 0
Therefore oxidation state of Fe in
Fe(CO)5 is
0.