Which of the following reactions represents the self- reduction process? (a) (b) (c)

No foreign catalyst or reducing agent is added for these reductions. All are undergoing self-reduction. Thermodynamic Principles of Metallurgy 37. Hydrogen gas will not reduce (a) heated cupric oxide (b) heated ferric oxide (c) heated stannic oxide (d) heated aluminium oxide The metals and elements that are below the hydrogen in the metal reactivity series can be reduced by the hydrogen. So, from the given options, heated aluminium cannot be oxidized by the hydrogen because the aluminium is above hydrogen in the metal reactivity series or aluminium is more reactive than hydrogen. 38.