11. The following statements relate to the extraction of metals:

I. Unreactive metals are often found as uncombined elements
II. Iron is more difficult to extract than copper
III. Sodium is extracted from its ore by heating with carbon

Which of these statements are true?

  • A.   I and II only
  • B.   I and III only
  • C.   II and III only
  • D.   I, II and III

Q12-13:
One of the reactions in the extraction of zinc is:

ZnO  + C → Zn + CO

  
12. Carbon is used to extract zinc from zinc oxide because ..
  • A.   carbon is less reactive than zinc
  • B.   carbon is more reactive than zinc
  • C.   carbon is a non-metal
  • D.   carbon is cheap
13. Which statement is correct about this reaction?
  • A.   carbon is reduced to carbon monoxide
  • B.   carbon monoxide is reduced to carbon
  • C.   zinc is oxidized to zinc oxide
  • D.   zinc oxide is reduced to zinc
14. Iron can be extracted in a blast furnace. The metal oxides are reduced by carbon monoxide, CO.

 

blast furnace
J Navas | CC 3.0

The chemical equation for the reduction of iron(III)oxide, Fe2O3 is..

  • A. Fe2O3 + CO → Fe2 + CO2
  • B. Fe2O3 + 3CO → Fe2 + 3CO2
  • C. Fe2O3 + CO → Fe + CO2
  • D. Fe2O3 + 3CO → 2Fe + 3CO2
15. Hematite, coke, limestone and hot air are the raw material used in the Blast Furnace.

Which statement is NOT correct about the reactions in the Blast Furnace?

  • A.   A high temperature is produced when the coke burns in hot air
  • B.   Limestone decomposes producing carbon monoxide
  • C.   Iron oxide in the hematite is reduced to iron by carbon monoxide
  • D.   Impurities in the hematite are converted to slag

Q16-19:
Aluminium is manufactured by the electrolysis of a molten mixture of aluminium oxide and cryolite using carbon as the positive electrode.

  

16. Which substances are formed at each electrode?

  anode cathode
A aluminium oxygen
B aluminium hydrogen
C oxygen aluminium
D hydrogen aluminium
17. Why does aluminium need to be extracted from its ore using electrolysis rather than heating with carbon?
  • A.   Electrolysis is a cheaper process than heating with carbon
  • B.   Aluminium is more abundant than iron in the Earth’s crust
  • C.   Aluminium is an expensive metal
  • D.   Aluminium is more reactive than carbon
18. Why is a mixture used as the electrolyte rather than pure aluminium oxide?
  • A.   Cryolite stops the electrodes from corroding away at high temperatures
  • B.   Aluminium ore is a mixture of aluminium oxide and cryolite
  • C.   Molten aluminium oxide alone does not conduct electricity
  • D.   The mixture has a lower melting point than pure aluminium oxide
19. Why must the positive electrode be continually replaced?
  • A.   The electrode melts at the temperature used in the process
  • B.   The aluminium formed reacts with the electrode forming an alloy
  • C.   The oxygen formed reacts with the electrode forming carbon dioxide
  • D.   The electrode reacts with the cryolite in the molten mixture
20. Which of the following is a disadvantage of recycling metals? scrap metal heap
  • A.   less energy is required compared to producing metals from metal ores
  • B.   fewer quarries and mines are needed
  • C.   used items require collection, transporting and sorting
  • D.   supplies of metal ores are preserved