(x)     What is to be considered when choosing the best method to extract a particular metal from its ore?

A    The metal 's economic value.

B     Its availability in an area.

C    The metal's ore impurities.

D    How it reacts with other materials. 

E    The metal's shininess.

The property of metal to be drawn into wires is called?

1. Conductivity
2. Malleability
3. Ductility
4. Decorating
5. Expansion.

In the blast furnace carbon monoxide is prepared by passing carbon dioxide over a red­hot coke. Carbon dioxide is

1.  an accelerator
2.  an oxidizing agent
3.  a reducing agent
4.  a catalyst
5.  oxidized.

10. (a) Explain the function of ceke and hot air in the extraction of iron from its ore.

(b) Account for the fact that aluminium is a vital element in our daily life. Give four points.

Explain six measures for minimizing the environmental degradation caused by extraction of metals in Tanzania.

State four steps employed in the extraction of moderate reactive metals.

Give one reason why Alluminium is chosen to make each of the following items:

1. Cooking foil

2. Overhead electric cables

3. Window frames

Identify and state the environmental problem caused by the gas which is released from the blast furnace in the extraction of iron from its oxide.

State the main raw material and the process involved in the manufacture of the following products.

1. Wood charcoal

2. Coke

3. Lampblack.

  (i) Arrange the following metals in order of increasing reactivity; zinc, magnesium, calcium, copper and mercury.

 (ii) Which one of the metals in (b) (i) above reacts with steam to form an oxide which is white when cold and yellow when hot?

  In the blast furnace, iron ore can be reduced using coke at a temperature of about 1300°C.

(i) Write an equation for the exothermic reaction that causes this high temperature.

(ii) State how carbon monoxide is formed.

(iii) Write a word equation for the formation of slag.

 Briefly explain how aluminum is obtained from its oxide.

Describe four common stages for the extraction of metals. Does the extraction of gold follow all four stages? Give reasons.

12.   (a)    Give three ways in which environmental destruction is likely to occur during extraction of metals.

(b)   The following equations represent the steps involved in the conversion stages of iron extraction in Bussener converter. Arrange the equations in chronological order from the first step to the last by writing the respective letter so as to get a complete explanation of the conversion stage.

   V: 2Cu₂0(S) +   Cu₂S(S)→     6Cu (l) + S0₂ (g)

  W:  FeO (l) + SiO₂(g) → FeSiO₃

   X: 2Cus(s) +30₂ (g) →          2Cu20(s) +2S0₂ (g)

   Y: 2FeS (l) +30₂ (g) → 2Feo(1) + 2S0₂ (g)                                          (7 marks)

Explain the meaning of the following:

(i) Malleable

(ii) Ductile

(iii) Brittle (3 marks)