D-And F-Block Elements Ques 142
Question: Iron is rendered passive by the action of
[IIT 1982; MP PET 1985; MP PMT 1987; DPMT 1984; KCET 1993]
Options:
A) Conc. $ H_2SO_4 $
B) Conc. $ H_3PO_4 $
C) Conc. $ HCl $
D) Conc. $ HNO_3 $
Show Answer
Answer:
Correct Answer: D
Solution:
Iron is rendered passive by conc. $ HNO_3 $ and other oxidising agents like $ K_2Cr_2O_7,,KMnO_4 $ , Chloric acid, chromic acid, silver nitrate etc. A specimen of passive iron can be rendered active by scratching the film mechanically or chemically.
