D-And F-Block Elements Ques 137
Question: Pure conc. $ HNO_3 $ makes iron passive as the surface is covered with protective layer of
[Orrisa JEE 2002; EAMCET 1993]
Options:
A) $ Fe_2O_3 $
B) FeO
C) $ Fe_3O_4 $
D) $ Fe{{(NO_3)}_3} $
Show Answer
Answer:
Correct Answer: C
Solution:
The passivity of iron is due to the formation of a thin insoluble and invisible iron film on surface which prevents its further reactions. The film is due to the formation of $ Fe_3O_4 $ .
