15 Extraction of metals Quiz | Chemistry Quiz #mcq.cetjob - Multiple choice questions and Objectives
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General principals of Extraction of metals Quiz | Chemistry Quiz

All the materials found in the earth are composed of elements. There are about 112 elements known which constitute the entire matter on the earth. Therefore, the elements are regarded as the building blocks of the universe. These are distributed in all the three main parts of the earth; atmosphere and lithosphere. Among these, the lithosphere constitutes the main source of most of the elements. The elements have been broadly divided into metals and non-metals on the basis of their physical and chemical properties. 

Occurrence of Metals

The element which have low chemical reactivity generally occur native or free or metallic state. e.g.  noble gas etc. The element which are chemically reactive generally occurs in the combined state. e.g. halogens, chalcogens, etc. The natural materials in which the metals occur in the earth are called minerals. The mineral from which the metal is conveniently and economically extracted is called an ore. All the ores are minerals but all minerals cannot be ores. Ores may be divided into four groups,
(1) Metallic core (siderophile) of the earth's crust contains (Mn, Fe, Co, Ni, Cu, Ru, Rb, Pd, Ag, Re, Os, Ir, Pt, Au). The entire composition of metals in earth crust may be given as,
Al (8.3%); Ca(3.6%); Na (2.8%); K (2.6%); Mg (2.1%); Ti (0.4%); Mn (0.1%); Fe (5.1%) other metals (0.1%).
(i) Native ores: These ores contain metals in a free state, e.g., silver, gold, platinum, mercury, copper, etc. These are found usually associated with rock or alluvial materials like clay, sand, etc. sometimes lumps of pure metals are also found. These are termed nuggets. Iron is found in free state as meteorites which also have 20 to 30% nickel.

Occurrence Quiz

1. A mineral is called an ore if 
(a) Metal present in mineral is precious 
(b) Metal can be extracted from it
(c) Metal can be extracted profitably from it
(d) Metal cannot be extracted from it

2. The highest quantity present in the atmosphere is of
(a) Oxygen (b) Hydrogen
(c) Nitrogen (d) Ozone 

3. Which of the following statement is correct
(a) Bauxite is an ore of aluminium
(b) Magnetite is an ore of manganese
(c) Haematite is  an ore of mercury
(d) Pyrites is an ore of phosphorus

4. Carnellite is a mineral of 

(a) Ca (b) Na 
(c) Mg (d) Zn 

5. The salt  which is least likely to be found in minerals is
(a) Chloride (b) Sulphate
(c) Sulphide (d) Nitrate

6. Which of the following ore is used for industrial extraction of aluminium in India
(a) Corundum (b) Keolin
(c) Cryolite (d) Bauxite
7. Bauxite is an oxide ore of

(a) Barium (b) Boron
(c) Bismuth (d) Aluminium

8. Cryolite is 
(a) Magnesium silicate
(b) Sodium borofluoride
(c) Sodium aluminium fluoride
(d) Magnesium silicate

9. Main ore of aluminium is

(a) Bauxite (b) Corundum
(c) Cryolite (d) Magnetite

10. Copper can be extracted from

(a) Kupfernickel (b) Dolomite
(c) Galena (d) Malachite

11. Argentite is a mineral of

(a) Copper (b) Silver
(c) Platinum (d) Gold

12. Which one of the following is an ore of silver
(a) Argentite (b) Stibnite
(c) Haematite (d) Bauxite

13. Important ore of zinc is
(a) Calamine (b) Cryolite
(c) Gibsite (d) Malachite
14. All ores are minerals, while all minerals are not ores because

(a) The metal can’t be extracted economically from all the minerals
(b) Minerals are complex compounds 
(c) The minerals are obtained from mines
(d) All of these are correct

15. Corundum is an ore of 
(a) Copper (b) Boron
(c) Aluminium (d) Sodium

16. Which one of the following is correct
(a) A mineral cannot be an ore
(b) An ore cannot be a mineral
(c) All minerals are ores
(d) All ores are minerals 

17. Which ore contains both iron and copper?
 (a) Cuprite (b) Chalcocite
(c) Chalcopyrite (d) Malachite


Concentration Quiz

18. Cassiterite is concentrated by
(a) Levigation
(b) Electromagnetic separation
(c) Floatation
(d) Liquifaction
SOL: (b) Cassiterite SnO2 or tinstone – an ore of tin being non-magnetic can be separated from magnetic impurities like Fe and Mn from this method.

19. Froth floatation process for the concentration of ores is an illustration of the  practical application of
(a) Adsorption (b) Absorption 
(c) Coagulation (d) Sedimentation 

20. Iron ore is concentrated by 
(a) Froth floatation (b) Electrolysis
(c) Roasting (d) Magnetic treatment

21. One of the following metals forms a volatile compound and this property is taken advantage for its extraction. This metal is
(a) Iron (b) Nickel
(c) Cobalt (d) Tungsten

22. Bauxite ore is concentrated by
(a) Froth flotation
(b) Electromagnetic separation
(c) Chemical separation
(d) Hydraulic separation 
SOL: (c) Chemical separation or Leaching.
In this powdered ore is treated with a suitable reagent which can dissolve the ore but not the impurities.

23. Ores like magnetite or tungstates in tin ores are concentrated by
(a) Froth floatation
(b) Magnetic separation
(c) Gravity separation
(d) Electrostatic separation
24. An ore like zinc blende is concentrated by 
(a) Froth floatation
(b) Magnetic separation
(c) Leaching
(d) Washing with water
SOL: (a) Froth floatation because it is sulphide ore ZnS

Roasting & Calcination Quiz

25. Roasting is generally done in case of the following

(a) Oxide ores (b) Silicate ores
(c) Sulphide ores (d) Carbonate ores

26. Heating of pyrites in air for oxidation of sulphur is called 

(a) Roasting (b) Calcination
(c) Smelting (d) Slagging
SOL: (c) In this process sulphides ores are converted into oxide ores 

27. A substance which reacts with gangue to form fusible material is called

(a) Flux (b) Catalyst
(c) Ore (d) Slag
SOL: (a)
28. The substance which is mixed with the ore for removal of impurities is termed as

(a) Slag (b) Gangue
(c) Flux (d) Catalyst
SOL: (c) Flux is added during smelting it combines with infusible gangue present in the ore to form a fusible mass known as slag. 

29. Which one of the furnaces among the following can produce the highest temperature 
(a) Muffle furnace
  (b) Blast furnace 
(c) Reverberatory furnace
  (d) Electric furnace 

30. In metallurgy, flux is a substance used to convert
(a) Infusible impurities to fusible material 
(b) Soluble impurities to insoluble impurities 
(c) Fusible impurities to infusible impurities 
(d) Mineral into silicate

31. In the manufacture of iron lime stone added to the blast furnace, the calcium ion ends in the form of
(a) Slag (b) Gangue
(c) Calcium metal (d) CaCO3 
SOL: (a) 

32. Flux added in the extraction of iron is
(a) Silica (b) Felspar
(c) Limestone (d) Flint
SOL: (c)Impurities of   is present in the iron ore so basic flux   is added. 

33. The smelting of iron in the blast furnace involves all the following process except
(a) Oxidation (b) Reduction
(c) Decomposition (d) Sublimation

34. When a metal is to be extracted from its ore, if the gangue associated with the ore is silica, then
(a) An acidic flux is needed
(b) A basic flux is needed
(c) Both acidic and basic flux are needed
(d) Neither of them is needed

35. Which statement is correct
(a) Gangues are carefully chosen to combine with the slag present in the ore to produce easily fusible flux to carry away the impurities
(b) Slags are carefully chosen to combine with the flux present in the ore to produce easily fusible gangue to carry away the impurities
(c) Gangues are carefully chosen to combine with the flux present in the ore to produce easily fusible slag to carry away the impurities
(d) Fluxes are carefully chosen to combine with the gangue present in the ore to produce easily fusible slag to carry away the impurities

36. Which of the following fluxes is used to remove acidic impurities in metallurgical process
(a) Silica (b) Lime stone
(c) Sodium chloride (d) Sodium carbonate
SOL: (b)Lime stone which is a flux used to remove acidic impurities in metallurgical process.

37. Roasting of copper pyrites ores is for the following purposes
(a) To burn off sulphur, arsenic, antimony etc. as oxides and convert all the iron and copper to their oxides
(b) To burn off arsenic, antimony etc. as oxides and burn off sulphur so that enough of it remains to combine with all the copper
(c) To burn off sulphur partially to leave enough to combine with arsenic, antimony etc. and to convert all the iron and copper to oxides
(d) To melt arsenic and antimony sulphides etc. and remove them by liquation and to burn off sulphur partially to leave enough to combine with copper and iron 

38. In the modern blast furnaces, the charge consists of a mixture of
(a) Calcined iron oxides + lime + anthracite coal
(b) Calcined iron oxides + limestone + coke 
(c) Hydrated iron oxides + dolomite + coke
(d) Iron pyrites + lime +bituminous coal
SOL: (b)

39. Flux is used to remove
(a) Silica
(b) Metal oxide
(c) All impurities from ores
(d) Silica and undesirable metal oxide
SOL: (d) Flux is used to remove silica and undesirable metal oxide.

40. Roasting is done in
(a) Blast furnace
(b) Open hearth furnace
(c) Electric furnace
(d) None of these
SOL: (a) Roasting is the process of heating the ore strongly in the presence of excess of air. It is generally carried in a reverberatory or blast furnace.

41. Refractory metals are used in construction of furnaces because
(a) They can withstand high temperature 
(b) They are chemically inert
(c) Their melting point is high
(d) None of these

Reduction to free Metal Quiz

42. Function of the flux added during smelting is
(a) To make ore porous
(b) To remove gangue
(c) To make reduction easier
(d) To precipitate slag

43. Alumino–thermic process is used for the extraction of metals, whose oxides are
(a) Fusible
(b) Not easily reduced by carbon
(c) Not easily reduced by hydrogen
(d) Strongly basic
SOL: (b)

44. In blast furnace iron oxide is reduced by
(a) Silica (b) CO 
(c) Carbon (d) Lime stone

45. Furnaces are lined with calcium oxide because
(a) It gives off oxygen on heating
(b) It gives strong light on heating
(c) It is refractory and basic
(d) It is not affected by acids

46. Alumina
(a) Is a good conductor of electricity
(b) Is a bad conductor of electricity
(c) Melts at 200C
(d) Is an electrovalent compound

47. Aluminium is prepared in large quantities by

(a) Heating cryolite in a limited quantity of air
(b) Reducing aluminium oxide with coke
(c) Reducing aluminium oxide with sodium
(d) Electrolysing aluminium oxide dissolved in fused electrolyte

48. After partial roasting, the sulphide of copper is reduced by

(a) Reduction by carbon
(b) Electrolysis 
(c) Self–reduction 
(d) Cyanide process 
SOL: (c) Self reduction :– Reduction of oxide ore of a metal by its own sulphide 
49. High purity copper metal is obtained by
(a) Carbon reduction
(b) Hydrogen reduction
(c) Electrolytic reduction
(d) Thermite reduction

Refining of crude metal Quiz

50. Cupellation process is used in the metallugry of
(a) Copper (b) Silver
(c) Aluminium (d) Iron 
SOL: (b) Cupellation method is used when the impure metals contain impurity of another metal which forms volatile oxide.

51. Metals are  
(a) Electropositive 
(b) Electronegative 
(c) Acceptor of electrons 
(d) None of these 
SOL: (a) Metals are electropositive elements because they have tendency to loose e- and forms + ve ions 

52. Electric refining is used for refining of
(a) Lead (b) Copper
(c) Iron (d) Sodium

53. Van Arkel method of purification of metals involves converting the metal to a
(a) Volatile stable compound
(b) Volatile unstable compound
(c) Non volatile stable compound
(d) None of the above
54. Zone refining is a method to obtain
(a) Very high temperature (b) Ultra pure Al
(c) Ultra pure metals (d) Ultra pure oxides
SOL: (c) Zone refining is employed for preparing extremely pure metals. 
It is based on the principle that when a molten solution of the impure metal is allowed to cool the pure metal crystallises out while the impurities remain in the melt. Ex :  Semiconductors like Si, Ge and Ga are purified by this method.

55. If the impurity in a metal has a greater affinity for oxygen and is more easily oxidised than the metal, then the purification of metal may be carried out by
(a) Poling
(b) Zone refining
(c) Electrolytic refining
(d) Cupellation

56. The process of ore dressing is carried out to 
(a) Remove the siliceous materials 
(b) Add flux to the mineral
(c) Convert the ore to oxide
(d) Remove the poisonous impurities
SOL: (a) Removal of silicious matter from ores is known as dressing or concentration of ore.
57. Wolframite ore is separated from tinstone ore by the process of
(a) Roasting
(b) Electromagnetic
(c) Smelting
(d) Calcination
SOL: (b) Wolframite ore FeWO4 is present in tin stone as impurities and it has same mass per unit volume as that of tin stone. So it is separated by electromagnetic separator because wolframite is magnetic in nature hence it gets attracted by magnet while tin stone doesn't.

58. Which process of reduction of mineral to the metal is suited for the extraction of copper from its ores with low copper content
(a) Metal displacement
(b) Auto reduction
(c) Chemical reduction
(d) Electrolytic reduction
SOL: (b)Auto reduction is used for the extraction of copper from its ore with low copper content.