1. 1
   A mining company extracts iron from iron oxide ore by heating it with carbon in a blast furnace, since iron is less reactive than carbon.

   (a)

   Which term describes this type of reaction?

   [1 mark]

   • AReduction
   • BNeutralisation
   • CElectrolysis
   • DCombustion

   (b)

   The company also processes a small amount of gold ore from the same site. Unlike iron, gold is found in the ground as the metal itself rather than as a compound. What does this indicate about gold's reactivity?

   [1 mark]

   • AGold is more reactive than carbon
   • BGold is very unreactive
   • CGold reacts readily with oxygen
   • DGold must be extracted using carbon

   (c)

   Explain why carbon can be used to extract iron from iron oxide, but cannot be used to extract a very reactive metal such as sodium from its oxide.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A small copper mine has become uneconomical to work using traditional mining because the remaining ore is too low-grade. The company decides to try bioleaching as an alternative method of extracting copper.

   (a)

   What does bioleaching involve?

   [1 mark]

   • APassing an electric current through the molten ore
   • BPlants absorbing metal compounds and being burned to leave an ash
   • CMelting the ore at very high temperatures using carbon
   • DBacteria producing a leachate solution containing metal compounds

   (b)

   Once bioleaching produces a solution containing copper compounds, which method could be used to obtain copper metal from this solution using scrap iron?

   [1 mark]

   • AElectrolysis of the solid iron
   • BDisplacement, because iron is less reactive than copper
   • CDisplacement, because iron is more reactive than copper
   • DCombustion of the iron in air

   (c)

   Evaluate one advantage and one disadvantage of using bioleaching to extract copper from low-grade ore, compared with traditional mining.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A coastal engineering firm is inspecting an iron pier that has been exposed to sea water and air for many years. Sections of the pier show significant rusting, while other sections, protected with blocks of zinc bolted onto the iron, show almost no rusting.

   (a)

   Explain why iron rusts when exposed to both air and water.

   [3 marks]

   (b)

   Explain, in terms of reactivity, why bolting blocks of zinc onto the iron pier prevents the iron from rusting, and describe one other method that could have been used to protect the iron instead.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A jewellery designer wants to make a ring described as "18 carat gold" and is deciding what mixture of metals to use, since pure gold is too soft for everyday wear. A cutlery manufacturer is separately deciding between using high carbon steel and low carbon steel for a new range of kitchen knives.

   (a)

   Discuss why alloys, rather than pure metals, are used in both of these products, explaining the general principle behind why alloying changes the properties of a metal.

   [6 marks]

   (b)

   The cutlery manufacturer is also considering whether to use stainless steel for a premium range of knives, instead of ordinary high or low carbon steel. Discuss what advantage stainless steel offers, and how its composition gives it this advantage.

   [6 marks]

   Total for question 4: 12 marks

End of questions