Question

25. Which oxide film is non-protective ?
(a) stable porous
(c) volatile
(b) stable non-porous
(d) both (a) and (c)​

Answer 1

The oxide film which is non-protective is stable porous and volatile. Hence, the correct option is d) Both (a) and (c).

• A porous film will have cracks or pores in the structure due to which the oxide will become non-protective. Through the pores, oxygen will react with the metal in the presence of moisture which will lead to rusting.
• A volatile film will be non-protective as it will have the chance to easily react and catch fire.