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					2007-CE
CHEM                               ST. JOSEPH’S COLLEGE

                  HONG KONG CERTIFICATE OF EDUCATION EXAMINATION 2007
2

                              CHEMISTRY             PAPER 2



    15th December 2006                                    Subject Code 160

    Total Mark: 40 (0.8 marks each)



    1.    When told to open this book, you should check that all the questions
          are there. Look for the words ‘END OF PAPER II’ after the last
          question.

    2.    All questions carry equal marks.

    3.    ANSWER ALL QUESTIONS. You should mark all your answers on the
          Multiple Choice Answer Sheet.

    4.    You should mark only ONE answer for each question. If your mark
          more than one answer, you will receive NO MARKS for that question.

    5.    No marks will be deducted for wrong answers.




    2007-CE-CHEM 2-1                   –1–
2007-CE-CHEM 2-2   –2–
There are 50 questions in this paper.

Choose the best answer for each question.

Candidates may refer to the Periodic Table printed on page 2 when
answering the questions.


1.   The atom of an element E contains 38 neutrons. The electronic
     arrangement of this atom is 2,8,18,3. Which of the following
     combinations about this atom is correct ?

                   Atomic number         Mass number

           A.          31                    38
           B.          31                    69
           C.          38                    38
           D.          38                    69


2.   Which of the following statements concerning the halogens are correct ?

     (1)    All halogens are gaseous elements.
     (2)    Reactivity of the halogens decreases down the group.
     (3)    The halogens react with sodium sulphite solution to give a
            colourless solution while sulphur does not.

            A.      (1) and (2) only
            B.      (1) and (3) only
            C.      (2) and (3) only
            D.      (1), (2) and (3)


3.   Which of the following pairs does NOT have equal number of electrons ?

            A.      Ne , N3–
            B.      Li+ , Be2+
            C.      P3–, Ar
            D.      Mg2+ , S2–




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2007-CE-CHEM 2-3                       –3–
4.   What will be observed after the circuit has been closed for 10 minutes ?




            A.     A purple patch slowly moves towards A.
            B.     A purple patch slowly moves towards B.
            C.     There are two purple patches – one slowly move towards
                   A and the other towards B.
            D.     A circular purple patch spreads out from the crystal in all
                   directions.


5.   Which of the following statements about ionic compounds is
     INCORRECT ?

            A.     An ionic compound is a compound made up of ions.
            B.     An ionic compound must have equal number of cations
                   and anions.
            C.     All ionic compounds have giant ionic structures.
            D.     Molten ionic compounds conduct electricity.


6.   Which of the following electron diagrams is INCORRECT ?

              A.

              B.

              C.


              D.




2007-CE-CHEM 2-4                         –4–
7.   Simple molecular substances usually have low melting points and boiling
     points. This is because

            A.     covalent bonds are weak forces of attraction.
            B.     the molecules are not regularly packed.
            C.     only weak intermolecular forces exist between molecules.
            D.     the substances are usually non-metals.


8.   The melting points of some chlorides are given below :

           NaCl       808 oC            MgCl2    714 oC
           SiCl4      –70 oC            SCl2     –80 oC

     What can be deduced from the above data ?

     (1)    NaCl can conduct electricity at 800 oC.
     (2)    MgCl2 is a liquid at 720 oC.
     (3)    SiCl4 is a covalent compound with a simple molecular structure.
     (4)    SCl2 is a covalent compound with a giant covalent structure.

            A.     (1) and (3) only
            B.     (1) and (4) only
            C.     (2) and (3) only
            D.     (2), (3) and (4) only


9.   Which of the following statements is/are true ?

     (1)    All substances with a giant structure are solids at room
            conditions.
     (2)    All covalent compounds are non-conductors of electricity when
            pure.
     (3)    All ionic substances are soluble in water.

            A.     (2) only
            B.     (1) and (2) only
            C.     (1) and (3) only
            D.     (1), (2) and (3)




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2007-CE-CHEM 2-5                      –5–
10. In an experiment using the set-up as shown below, a gas is evolved and
    burns at the jet. Metal X is probably




            A.       zinc
            B.       aluminium
            C.       silver
            D.       lead


11. An element X reacts violently with water to form a hydroxide of formula
    XOH which is soluble in water. X will probably

    (1)   be a metal
    (2)   form a gaseous oxide
    (3)   form colourless compounds.

          A.       (1) and (2) only
          B.       (1) and (3) only
          C.       (2) and (3) only
          D.       (1), (2) and (3)




2007-CE-CHEM 2-6                        –6–
12. For a single piece of iron, some parts may rust more readily than the rest.
    Refer to the bent iron nail shown below. Which part would rust LEAST
    readily?




13. Metals X and Y react with dilute hydrochloric acid to liberate hydrogen,
    but metal Z has no reaction with the dilute acid. The carbonate of metal
    Y decomposes on heating but the carbonate of metal X does not. Which
    of the following arrangements represents the order of increasing
    reactivity of the three metals ?

            A.     Y<Z<X
            B.     Z<Y<X
            C.     Z<X<Y
            D.     X<Y<Z


14. The following mixtures are heated strongly. In which one is a reaction
    most likely to occur ?

            A.     Magnesium and copper(II) oxide
            B.     Iron and aluminium oxide
            C.     Zinc and magnesium oxide
            D.     Lead and zinc oxide




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2007-CE-CHEM 2-7                   –7–
Questions 15 – 16 refer to the following figure :




15. Which of the following metals, when used as electrode X, would produce
    the largest positive reading on the voltmeter ?

            A.     Tin
            B.     Lead
            C.     Copper
            D.     Zinc


16. If electrode X is iron, which of the following statements concerning this
    cell is correct ?

            A.     Iron is the positive electrode.
            B.     The voltmeter registers a negative reading.
            C.     Electrons flow from silver to iron.
            D.     Iron dissolves to form Fe2+(aq) ions.



17. The oxidation number of copper in [Cu(NH3)4]2+ is

            A.     –2
            B.     0
            C.     +2
            D.     +4




2007-CE-CHEM 2-8                         –8–
18. In which of the following equations is the underlined substance
    reduced ?

            A.                            
                   2 HCl(aq) + Na2SO3(s)   2 NaCl(aq) + SO2(g) + H2O(l)
            B.     2 Fe2+(aq) + Cl2(g)   2 Fe3+(aq) + 2 Cl–(aq)
                                        
            C.                              
                   Pb(OH)2(s) + 2 HNO3(aq)   Pb(NO3)2(aq) + 2 H2O(l)
            D.                        
                   Zn(s) + H2SO4(aq)   ZnSO4(aq) + H2(g)


19. Which of the following is NOT a redox reaction ?

            A.     Mixing silver nitrate solution and dilute hydrochloric acid.
            B.     Adding a copper wire to silver nitrate solution.
            C.     Passing steam over heated magnesium.
            D.     Heating a mixture of iron and sulphur.


20. Consider the chemical equation below :

                               
       a HNO3(aq) + b H2S(aq)   c NO(g) + d S(s) + e H2O(l)

    If the above equation is balanced, which of the following sets of the
    values of a, b, c, d and e is correct ?

                   a b     c   d   e

            A.     3   2   3   2   4
            B.     2   3   2   3   4
            C.     2   1   2   2   2
            D.     3   2   2   3   4




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2007-CE-CHEM 2-9                       –9–
21. Which of the following diagrams show(s) a beaker in which electrolysis
    takes place ? (Graphite electrodes are used in all cases)




            A.      (2)   only
            B.      (1)   and (2) only
            C.      (1)   and (3) only
            D.      (3)   and (4) only


22. Which of the following changes may take place at the anode during
    electrolysis ?

    (1)     4 OH–(aq)   O2(g) + 2 H2O(l) + 4 e–
                       
    (2)     2 Cl–(aq)   Cl2(g) + 2e–
                       
    (3)     Fe3+(aq) + e–   Fe2+(aq)
                           
    (4)     Cu(s)   Cu2+(aq) + 2 e–
                   

            A.      (1) only
            B.      (3) only
            C.      (1) and (2) only
            D.      (1), (2) and (4) only




2007-CE-CHEM 2-10                           – 10 –
23. When sodium hydroxide solution is electrolysed using graphite
    electrodes, hydrogen is liberated at cathode, but not sodium. The best
    explanation would be :

            A.      H+(aq) ion has a higher tendency to accept electrons than
                    Na+(aq) ion.
            B.      The H+(aq) ions move faster than Na+(aq) ions.
            C.      The sodium which is liberated reacts with water to give off
                    hydrogen.
            D.      There are more H+(aq) ions in the solution than Na+(aq)
                    ions.


24. If 0.2 M aqueous solutions of the following compounds are electrolysed
    using graphite electrodes, which of the following electrolytes will give
    hydrogen at cathode and oxygen at anode ?

    (1)     Copper(II) chloride
    (2)     Potassium hydroxide
    (3)     Silver nitrate
    (4)     Nitric acid

            A.      (1)   and   (2)   only
            B.      (1)   and   (3)   only
            C.      (2)   and   (4)   only
            D.      (3)   and   (4)   only


25. Which of the following statements concerning anodization of aluminium
    is/are correct ?

    (1)     Anodization can increase the thickness of the oxide layer on
            aluminium articles.
    (2)     During the anodization process, aluminium articles are
            connected to the cathode.
    (3)     After anodization, aluminium articles will not be easily corroded.

            A.      (1)   only
            B.      (2)   only
            C.      (1)   and (3) only
            D.      (2)   and (3) only


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2007-CE-CHEM 2-11                        – 11 –
26. Consider the chemical reaction below :




     What would be the visible changes in the above set-up ?

                          Bromine water                   Limewater

            A.              colourless
                    yellow                                     
                                                     colourless  milky
            B.             
                    yellow  colourless              remain colourless
            C.      remains yellow                               
                                                     colourless  milky
            D.      remains yellow                   remain colourless


27. Which of the following solutions has the highest pH value ?

            A.      1.0   M   sodium hydrogensulphate solution
            B.      1.0   M   sodium carbonate solution
            C.      1.0   M   hydrochloric acid
            D.      1.0   M   sodium hydrogencarbonate solution


28. Which of the following salts is INSOLUBLE in water ?

            A.      Li2SO4
            B.      (NH4)2CO3
            C.      MgCO3
            D.      NaNO2




2007-CE-CHEM 2-12                           – 12 –
29. Vinegar has a pH value of 3. Which of the following substances, when
    added to vinegar, would increase its pH value?

    (1)     Dilute sulphuric acid
    (2)     Solid sodium hydrogencarbonate
    (3)     Liquid ammonia
    (4)     Calcium

            A.      (1) only
            B.      (1) and (4) only
            C.      (2) and (3) only
            D.      (2), (3) and (4) only


30. Which of the following methods is best for preparing potassium nitrate ?

            A.      Add     potassium   sulphate solution to nitric acid.
            B.      Add     potassium   hydroxide solution to nitric acid.
            C.      Add     potassium   to nitric acid.
            D.      Add     potassium   to zinc nitrate solution.


31. Which of the followings are important use of sulphur dioxide ?

    (1)   To kill germs in drinking water
    (2)   To manufacture sulphuric acid
    (3)   To bleach paper

            A.      (1) and (2) only
            B.      (1) and (3) only
            C.      (2) and (3) only
            D.      (1), (2) and (3)


32. If 1 g of 18 O contains y atoms, how many atoms are present in 7 g of    14
                                                                                  N?

            A.      4   y
            B.      7   y
            C.      8   y
            D.      9   y



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2007-CE-CHEM 2-13                       – 13 –
33. 4.98 g of Na2CO3  nH2O, on strong heating, left 2.12 g of anhydrous salt.
    What is the value of n ?

    (Relative atomic masses : H = 1.0, C = 12.0, O = 16.0, Na = 23.0)

            A.      1
            B.      5
            C.      8
            D.      10


34. 1.35 g of an organic dibasic acid were dissolved in water and made up to
    250 cm3 of solution. 25.0 cm3 of this solution required 30.0 cm3 of 0.100 M
    sodium hydroxide solution for complete neutralization. What is the molar
    mass of the acid ?

            A.      45 g mol–1
            B.      60 g mol–1
            C.      90 g mol–1
            D.      180 g mol–1


35. Which of the following solutions contains the greatest number of ions ?

            A.      60 cm3 of 0.1 M Na3PO4
            B.      90 cm3 of 0.1 M K2SO4
            C.      90 cm3 of 0.05 M KNO3
            D.      120 cm3 of 0.05 M AgNO3


36. Suppose 0.100 mole of copper was reacted to form copper(I) oxide. The
    mass of copper(I) oxide obtained is

    (Relative atomic masses : O = 16.0, Cu = 63.5)

            A.      3.18   g
            B.      6.35   g
            C.      7.15   g
            D.      14.3   g




2007-CE-CHEM 2-14                        – 14 –
37. When a mixture of 0.80 g of oxygen and 0.20 g of hydrogen is exploded,
    the volume of the remaining gas at room temperature and pressure will
    be

    (Relative atomic masses : H = 1.0, O = 16.0; Molar volume of a gas at
    room temperature ad pressure = 24 dm 3 )

            A.      2.4   dm3
            B.      1.2   dm3
            C.      0.9   dm3
            D.      0.6   dm3


38. One mole of an organic compound is completely burnt in oxygen. Which
    of the following compounds produces exactly three moles of water ?

            A.      Butane
            B.      Butan-2-ol
            C.      Ethane
            D.      Propane

39. Which of the following is a non-renewable source of energy ?

            A.      Tidal power
            B.      Wind power
            C.      Hydroelectric power
            D.      Nuclear power


40. Gasohol is a cleaner fuel than petrol because

    (1)     gasohol tends to undergo complete combustion more readily
            than petrol alone.
    (2)     ethanol can be made from crops which are renewable energy
            sources.
    (3)     gasohol contains no lead compounds.

            A.      (1) only
            B.      (1) and (3) only
            C.      (2) and (3) only
            D.      (1), (2) and (3) only


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2007-CE-CHEM 2-15                   – 15 –
41. Referring to the reaction of sulphur dioxide and oxygen, which of the
    following can be deduced from the chemical equation below ?

           2SO2(g) + O2(g)         SO3(g)             H = –196 kJ mol-1

    (1)         The reaction is exothermic.
    (2)         SO3(g) can decompose to form SO2(g) and O2(g).
    (3)         The reaction is carried out at one atmospheric pressure.

                A.    (1) only
                B.    (1) and (2) only
                C.    (2) and (3) only
                D.    (1), (2) and (3)


42. Consider the flowing mercury cell below :
                                         Anode (+)



                       Gas




   Used brine                                                    Saturated brine



                                                                 Cathode (–)




    Which of the following statements about the flowing mercury cell is
    INCORRECT ?

                A.    Mercury acts as the cathode in the electrolysis.
                B.    The used brine has a high concentration of sodium
                      hydroxide.
                C.    Very pure chlorine and sodium hydroxide would be
                      obtained.
                D.    Losses of mercury to the environment may occur, causing
                      serious pollution problems to the areas nearby.




2007-CE-CHEM 2-16                            – 16 –
43. When chlorine water is exposed to sunlight for some time, a gas X is
    collected.




    The gas X

            A.      has a ‘pop’ sound with a burning splint.
            B.      has the smell of swimming pool.
            C.      can turn moist blue litmus paper red.
            D.      can relight a glowing splint.


44. Which of the following statements about pure acids is correct ?

            A.      They   are covalent compounds.
            B.      They   contain hydrogen ions.
            C.      They   are liquids at room condition.
            D.      They   are strong oxidizing agents.


45. Which of the following statements about all exothermic reactions is
    correct ?

            A.      A catalyst is needed to start each exothermic reaction.
            B.      Light is emitted during the reactions.
            C.      All exothermic reactions are redox reactions.
            D.      The products of the reactions have less heat content than
                    the reactants have.


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2007-CE-CHEM 2-17                    – 17 –
46. A liquid is to be electrolysed and two test tubes full of liquid are placed
    over inert electrodes. The diagram below shows the apparatus after a
    current has passed for some time.

                            Test tube                 Test tube

                                                            Gas y
                            Gas X




          Volume of Gas X           2
                             =
          Volume of Gas Y           1                     Inert electrodes




     Which of the followings could be the liquid undergoing electrolysis ?

            A.      Dilute sulphuric acid
            B.      Concentrated aqueous sodium chloride
            C.      An aqueous solution of sugar
            D.      Concentrated aqueous copper(II) sulphate




2007-CE-CHEM 2-18                        – 18 –
47. Hydrochloric acid is added to barium hydroxide solution. Which of the
    following graphs concerning the electrical conductivity of the resulting
    solution is correct ?

    A.    current
                                                 B.




                                                      current
                            Volume of acid                      Volume of acid

     C.                                          D.
          current




                                                      current




                            Volume of acid                      Volume of acid




48. Which of the following statements about a zinc-carbon dry cell is
    INCORRECT ?

                    A.   The negative terminal of the cell is the zinc case.
                    B.   The positive terminal is the carbon rod.
                    C.   The carbon powder increases the conductivity of the
                         electrolyte.
                    D.   Manganese(IV) oxide is used to accelerate the formation
                         of zinc ion.




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2007-CE-CHEM 2-19                            – 19 –
49. Dilute nitric acid is usually NOT used to acidify aqueous solutions of
    oxidizing agents such as potassium dichromate and potassium
    permanganate because dilute nitric acid

            A.                 is a strong acid.
            B.                 is volatile.
            C.                 is an oxidizing agent and will compete for the reducing
                               agent.
            D.                 reacts with the oxidizing agents.


50. Two experiments (I and II) were carried out to measure the rate of
    production of carbon dioxide from by adding excess magnesium into
    dilute hydrochloric acid solution.

                               Experiment           Solution used
                                 I                  100 cm3 of
                                                    1.0 M HCl(aq)

                                  II                300 cm3 of
                                                    0.02 M HCl(aq)

     Which of the following correctly shows the experiment results?
         A.                                B.


                                               I                                      I
               Volume of CO2




                                                               Volume of CO2




                                               II                                     II




                                       Time                                    Time
          C.                                             D.
                                               II                              II
               Volume of CO2




                                                               Volume of CO2




                                               I
                                                                               I




                                       Time                                    Time

                                         – END OF PAPER II –

2007-CE-CHEM 2-20                                     – 20 –

				
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