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Pure conc. HNO(3) makes iron passive as ...

Pure conc. `HNO_(3)` makes iron passive as the surface is covered with protective layer of

A

`Fe_2O_3`

B

`FeO`

C

`Fe_3O_4`

D

`Fe(NO_3)_3`

Text Solution

Verified by Experts

The correct Answer is:
C
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`.
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ERRORLESS-THE d-AND f- BLOCK ELEMENTS -NCERT BASED QUESTIONS (Compounds of Transitional Elements)
  1. Iron is dropped in dil. HNO(3) , it gives

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  2. Steel becomes soft and pliable by

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  3. Pure conc. HNO(3) makes iron passive as the surface is covered with pr...

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  4. Red hot iron absorbs SO(2) giving the product

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  5. If steel is heated to a temperature well below red hot and is then coo...

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  6. Railway wagon axles are made by heating rods of iron embedded in charc...

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  7. Steel contains

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  8. The most convenient method to protect the bottom of the ship made of i...

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  9. When SCN^(-) is added to an aqueous solution containing Fe(NO(3))(3), ...

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  10. The protection of steel by chrome plating is due to

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  11. KI and CuSO4 solution when mixed give .

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  12. Copper displaces Which of the metal from their salt solutions?

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  13. From a solution of CuSO4 the metal used to recover copper is

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  14. If excess of NH(4)OH is added to CuSO(4) solution, it forms blue colou...

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  15. When CuSO4 solution is added to K4[Fe(CN)6], the formula of the produ...

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  16. When metallic copper comes in contact with mositure, a green powdery/p...

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  17. Colourless solutions of the following four salts are placed separately...

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  18. The metal which can be used to obtain metallic Cu from aqueou...

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  19. Identify the statement which is not correct regarding CuSO4?

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  20. On adding excess of NH(3) solution to CuSO(4) solution, the dark blue ...

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