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#### Metallurgy one marks two marks three marks five marks

12th Standard EM

Reg.No. :
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Chemistry

Time : 02:00:00 Hrs
Total Marks : 100
Part-A
25 x 1 = 25
1. Bauxite has the composition

(a)

Al2O3

(b)

Al2O3nH2O

(c)

Fe2O3.2H2O

(d)

None of these

2. Roasting of sulphide ore gives the gas (A).(A) is a colourless gas. Aqueous solution of (A) is acidic. The gas (A) is

(a)

CO2

(b)

So3

(c)

SO2

(d)

H2S

3. Which one of the following reaction represents calcinations?

(a)

$2Zn+{ O }_{ 2 }\rightarrow 2ZnO$

(b)

$2ZnS+3O_{ 2 }\rightarrow 2ZnS+3O_{ 2 }\rightarrow 2ZnO_{ 2 }\rightarrow 2ZnO+2SO_{ 2 }$

(c)

$MgCO_{ 3 }\rightarrow MgO+CO_{ 2 }$

(d)

Both (a) and (c)

4. The metal oxide which cannot be reduced to metal by carbon is

(a)

PbO

(b)

AL2O3

(c)

ZnO

(d)

Feo

5. Which of the metal is extracted by Hall-Heroult process?

(a)

Al

(b)

Ni

(c)

Cu

(d)

Zn

6. Which of the following statements, about the advantage of roasting of sulphide ore before reduction is not true?

(a)

$\Delta { G }_{ f }^{ 0 }$ of sulphide is greater than those for CS2 and H2S

(b)

$\Delta { G }_{ r }^{ 0 }$ is negative for roasting of sulphide ore to oxide

(c)

Roasting of the sulphide to its oxide is thermodynamically feasible

(d)

Carbon and hydrogen are suitable reducing agents for metal sulphides

7. Match items in column - I with the items of column – II and assign the correct code.

 Column-I Column-II A. Cyanide process (i) Ultrapure Ge B Froth floatation process (ii) Dressing of ZnS C Electrolytic reduction (iii) Extraction of Al D Zone refining (iv) Extraction of Au (v) Purification of Ni
(a)
 A B C D
(b)
 A B C D (i) (ii) (iii) (iv)
(c)
 A B C D (iii) (iv) (v) (i)
(d)
 A B C D (ii) (iii) (i) (v)
8. Wolframite ore is separated from tinstone by the process of

(a)

Smelting

(b)

Calcination

(c)

Roasting

(d)

Electromagnetic separation

9. Which one of the following is not feasible

(a)

$Zn(s)+C{ u }^{ 2+ }\left( aq \right) \rightarrow Cu\left( s \right) +{ Zn }^{ 2+ }(aq)$

(b)

$Cu(s)+Z{ n }^{ 2+ }(aq)\longrightarrow Zn(s)+{ Cu }^{ 2+ }(aq)$

(c)

$Cu(s)+2Ag^{ + }(aq)\longrightarrow Ag(s)+{ Cu }^{ 2+ }(aq)$

(d)

$Fe(s)+{ Cu }^{ 2+ }(aq)\longrightarrow Cu(s)+{ Fe }^{ 2+ }(aq)$

10. Electrochemical process is used to extract

(a)

Iron

(b)

(c)

Sodium

(d)

silver

11. Flux is a substance which is used to convert

(a)

Mineral into silicate

(b)

Infusible impurities to soluble impurities

(c)

Soluble impurities to infusible impurities

(d)

All of these

12. Which one of the following ores is best concentrated by froth – floatation method?

(a)

Magnetite

(b)

Hematite

(c)

Galena

(d)

Cassiterite

13. In the extraction of aluminium from alumina by electrolysis, cryolite is added to

(a)

Lower the melting point of alumina

(b)

Remove impurities from alumina

(c)

Decrease the electrical conductivity

(d)

Increase the rate of reduction

14. Zinc is obtained from ZnO by

(a)

Carbon reduction

(b)

Reduction using silver

(c)

Electrochemical process

(d)

Acid leaching

15. Cupellation is a process used for the refining of

(a)

Silver

(b)

(c)

Copper

(d)

iron

16. Extraction of gold and silver involves leaching with cyanide ion. silver is later recovered by (NEET-2017)

(a)

Distillation

(b)

Zone refining

(c)

Displacement with zinc

(d)

liquation

17. Considering Ellingham diagram, which of the following metals can be used to reduce alumina? (NEET-2018)

(a)

Fe

(b)

Cu

(c)

Mg

(d)

Zn

18. The following set of reactions are used in refining Zirconium
$(impure)+2I_{ 2 }\overset { 523k }{ \longrightarrow } ZrI_{ 4 }$
${ ZrI }_{ 4 }\overset { 1800K }{ \longrightarrow } Zr(pure)+{ 2I }_{ 2 }$
This method is known as

(a)

Liquation

(b)

van Arkel process

(c)

Zone refining

(d)

Mond’s process

19. Which of the following is used for concentrating ore in metallurgy?

(a)

Leaching

(b)

Roasting

(c)

Froth floatation

(d)

Both (a) and (c)

20. The incorrect statement among the following is

(a)

Nickel is refined by Mond’s process

(b)

Titanium is refined by Van Arkel’s process

(c)

Zinc blende is concentrated by froth floatation

(d)

In the metallurgy of gold, the metal is leached with dilute sodium chloride solution

21. In the electrolytic refining of copper, which one of the following is used as anode?

(a)

Pure copper

(b)

Impure copper

(c)

Carbon rod

(d)

Platinum electrode

22. Which of the following plot gives Ellingham diagram

(a)

$\Delta SVsT$

(b)

$\Delta { G }^{ 0 }VsT$

(c)

$\Delta { G }^{ 0 }Vs\cfrac { 1 }{ T }$

(d)

$\Delta { G }^{ 0 }Vs{ T }^{ 2 }$

23. In the Ellingham diagram, for the formation of carbon monoxide

(a)

$\left( \cfrac { \Delta { S }^{ 0 } }{ \Delta T } \right)$

(b)

$\left( \cfrac { \Delta { G }^{ 0 } }{ \Delta T } \right)$ is positive

(c)

$\left( \cfrac { \Delta { G }^{ 0 } }{ \Delta T } \right)$ is negative

(d)

initially $\left( \cfrac { \Delta T }{ \Delta { G }^{ 0 } } \right)$ is positive, after 700oC,$\left( \cfrac { \Delta { G }^{ 0 } }{ \Delta T } \right)$ is negative

24. Which of the following reduction is not thermodynamically feasible?

(a)

${ Cr }_{ 2 }{ O }_{ 3 }+2Al\longrightarrow { Al }_{ 2 }{ O }_{ 3 }+2Cr$

(b)

${ Al }_{ 2 }{ O }_{ 3 }+2Cr\longrightarrow { Cr }_{ 2 }{ O }_{ 3 }+2Sl$

(c)

$3Ti{ O }_{ 2 }+4Al\longrightarrow 2A{ l }_{ 2 }{ O }_{ 3 }+3Ti$

(d)

none of these

25. Which of the following is not true with respect to Ellingham diagram?

(a)

Free energy changes follow a straight line. Deviation occurs when there is a phase change.

(b)

The graph for the formation of CO2 is a straight line almost parallel to free energy axis.

(c)

Negative slope of CO shows that it becomes more stable with increase in temperature

(d)

Positive slope of metal oxides shows that their stabilities decrease with increase in temperature

26. Part-B
13 x 2 = 26
27. What is the difference between minerals and ores?

28. What are the various steps involved in extraction of pure metals from their ores?

29. What is the role of Limestone in the extraction of Iron from its oxide Fe2O3?

30. Which type of ores can be concentrated by froth floatation method? Give two examples for such ores.

31. Out of coke and CO, which is better reducing agent for the reduction of ZnO? Why?

32. Describe a method for refining nickel

33. What is leaching?

34. What is distillation?

35. What is the role of silica in the extraction of copped? (or)
Describe the role of SiO2 in the extraction of Cu from Copper matte.

36. The reaction
${ Cr }_{ 2 }{ O }_{ 3 }+2{ Al }_{ (s) }\longrightarrow { Al }_{ 2 }O_{ 3 }+2Cr$
$\Delta { G }^{ 0 }=-421KJ$ is thermodynamically feasible why does it not take place at room temperature?

37. What is the role of graphite rods in the electro metallurgy of aluminium?

38. Write the chemical reactions involved in the extraction of gold by cyanide process. Also give the role of zinc in the extraction.

39. Name and discuss the principle involved in obtaining silicon of high purity.

40. Part-C
8 x 3 = 24
41. Explain zone refining process with an example using the Ellingham diagram given below

42. (A) Predict the conditions under which
(i) Aluminium might be expected to reduce magnesia.
(ii) Magnesium could reduce alumina.
(B) Carbon monoxide is more effective reducing agent than carbon below 983K but, above this temperature, the reverse is true –Explain.
(c) it is possible to reduce Fe2O3 by coke at a temperature around 1200K

43. Give the uses of zinc.

44. Explain the electrometallurgy of aluminium

45. Explain the following terms with suitable examples.
(i) Gangue
(ii) slag

46. Give the basic requirement for vapour phase refining.

47. What is vapour phase method?

48. Distinguish Roasting and Calcination

49. Part-D
5 x 5 = 25
50. Describe the role of the following in the process mentioned.
(i) Silica in the extraction of copper.
(ii) Cryolite in the extraction of aluminium.
(iii) Iodine in the refining of Zirconium.
(iv) Sodium cyanide in froth floatation.

51. Explain the principle of electrolytic refining with an example.

52. The selection of reducing agent depends on the thermodynamic factor: Explain with an example.

53. Give the limitations of Ellingham diagram

54. Write a short note on electrochemical principles of metallurgy.