HKCE PAST PAPERS 86-94/SECTION 2/PAGE 1
SECTION 2
COMMON METALS
1986 21. Which of the following will occur when a piece of magnesium ribbon is added to very dilute nitric acid? A H+(aq) + OH-(aq) → H2O(l) B 2H+(aq) + 2e- → H2(g) C NO3-(aq) + 4H+(aq) + 3e- → NO(g) + 2H2O(l) D NO3-(aq) + 2H+(aq) + e- → NO2(g) + H2O(l)
42. Which of the following metal oxides can be reduced by the method illustrated in the above diagram? (1) Fe2O3 (2) MgO (3) PbO A (2) only B (3) only C (1) & (2) only D (1) & (3) only 49. Which of the following metals will NOT displace copper ions from aqueous copper(II) sulphate? A silver B iron
C D
zinc aluminium
1987 9.
The action of dilute nitric acid on zinc is represented by the following equation: x HNO3(aq) + y Zn(s) → y Zn(NO3)2(aq) + z H2O(l) + 2 NO(g) The values of x, y and z in the balanced equation are A 3, 4 and 1. B 3, 8 and 2. C 4, 3 and 2. D 8, 3 and 4.
12. Tin plating can be used to prevent iron cans from rusting because A tin is higher than iron in the electrochemical series. B the tin protects the iron from exposure to air. C tin corrodes more readily than iron. D the tin and the iron readily form an alloy which does not corrode. 1988 12. A metal X displaces copper from copper(II) sulphate solution but does not displace zinc from zinc sulphate solution. Which of the following represents an increasing order for the reducing power of the three metals? A Cu < X < Zn B X < Cu < Zn C Zn < X < Cu D Zn < Cu < X 13. In which of the following cases would the rusting of the iron nail be most rapid?
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36. Which of the following metal oxides, when heated on a charcoal block, can be reduced to the corresponding metals? (1) CuO (2) PbO (3) ZnO A (1) & (2) only B (1) & (3) only C (2) & (3) only D (1), (2) & (3) 37. Which of the following processes could be used to slow down corrosion of an iron nail? (1) painting the nail (2) coating a layer of zinc on the nail (3) wrapping a strip of copper around the nail (4) putting the nail under distilled water A (1) & (2) only B (1) & (3) only C (2) & (4) only D (1), (3) & (4) only 1990 7. 38. Which of the following metal oxides can be reduced by carbon? (1) magnesium oxide (2) iron(III) oxide (3) copper(II) oxide A (1) & (2) only B (1) & (3) only C (2) & (3) only D (1), (2) & (3) 1989
The reaction between lead(II) nitrate solution and sodium hydrogencarbonate solution can be represented by the equation below: Pb2+(aq) + 2 HCO3-(aq) → PbCO3(x) + H2O(y) + CO2(z) Which of the following combinations for x, y and z is correct? x y z A aq aq aq B aq l g C s aq g D s l g
15. The reddish-brown rust that forms on the surface of iron can be removed by using A paraffin oil.
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B C D
dilute sulphuric acid. concentrated ammonia solution. dilute sodium hydroxide solution.
(3) lead A (1) & (2) only B (1) & (3) only C (2) & (3) only D (1), (2) & (3)
1991 8.
X, Y and Z are metals. Y can displace X from a solution of the nitrate of X. Oxides of X and Y can be reduced by hydrogen but not the oxides of Z. Which of the following arrangements represents the correct descending order of reactivity of the metals? A Z>Y>X B X>Y>Z C Z>X>Y D X>Z>Y
1992
31. In the above experiment, a gas is evolved and burns at the jet. Metal X is probably A zinc. B aluminium. C magnesium. D copper. 34. Which of the following metals can be obtained by reducing their oxides with carbon? (1) iron (2) calcium
1993 7.
CO2(g) + CaCO3(x) + H2O(y) → Ca(HCO3)2(z) In the above chemical equation, which of the following combinations is correct? x y z A aq l aq B s aq s C s l s D s l aq
14. The carbonates of three metals W, X and Y are separately heated strongly and the results obtained are tabulated below: Metal Action of heat on metal carbonate W CO2(g) and O2(g) evolved X No reaction Y CO2(g) evolved Which of the following arrangements represents the correct decreasing order of reactivity of the metals? A W>X>Y B W>Y>X C X>Y>W D Y>W>X Direction: Questions 20 and 21 refer to the following experiment: Three different pairs of metal wires are placed separately in petri dishes (as shown in the diagram below) containing a mixture of gelatin, potassium hexacyanoferrate(III) solution and phenolphthalein solution.
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B C D
(1) & (3) only (2) & (3) only (1), (2) & (3)
1994 5.
20. Which of the following statements are correct? (1) The iron wire in Dish I does not corrodes readily. (2) The iron wire in Dish II corrodes readily. (3) The iron wires in Dish III do not corrode. A (1) & (2) only B (1) & (3) only C (2) & (3) only D (1), (2) & (3) 21. In Dish II, which of the following colours will develop around the iron wire and the copper wire? iron wire copper wire A pink blue B blue pink C pink no colour D blue no colour 26. On heating, blue copper(II) sulphate crystals gradually change to a white powder. Which of the following statements are correct? (1) Heat would be liberated if water is added to the white powder. (2) On further heating, the white powder would turn reddish-brown. (3) A chemical change occurs during the heating of the blue crystals. A (1) & (2) only
The reaction between sodium hydrogen-carbonate solution and zinc sulphate solution can be represented by the following equation: 2 NaHCO3(aq) + ZnSO4(aq) → Na2SO4(x) + ZnCO3(y) + H2O(z) + CO2(g) Which of the following combinations is correct? x y z A aq aq aq B aq aq l C aq s l D s aq l