Question

Which of the following processes does not involve oxidation of iron?

• A. Decolourization of blue $CuSO_{4}$ solution by iron
• B. Formation of $Fe\left(\right.CO\left(\left.\right)_{5}$ from Fe
• C. Liberation of $H_{2}$ from steam by iron at high temperature
• D. Rusting of iron sheets

Answer 1

Answer: (B)

$Fe^{0}+5CO \rightarrow \left[\right.Fe^{0}\left(\right.CO\left(\left.\right)_{5}\left]\right.$
As no change in the oxidation state of iron occurs so it is not an oxidation reaction.
In rest other iron gets oxidised, for example
$\overset{0}{F e}+CuSO_{4} \rightarrow \overset{2 +}{F e}SO_{4}+Cu$