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

Step-by-step solution

(i) Rusting of iron F e → F e 3 + ( o x i d a t i o n ) (ii) C u 2 + + F e → F e 2 + + C u o x i d a t i o n F e + H 2 S O 4 → F e S O 4 + H 2 ↑ g ( o x i d a t i o n ) (iii) In the formation of Iron carbonyl from Fe, the oxidation number does not change at all. F e 0 + 5 C O → F e 0 ( C O ) 5 (iv) Fe + H 2 O → Fe 2 O 3 + H 2