1999 Paper 2

HON G KO NG EXAMINATION

AUT HORITY

HON G KO NG CERTI FICATE OF EDUCATIO N EXAMIN ATION 1999

CH EMIS TR Y P APER II 10.45am-11.45am(1 hour ) 1. Read carefully the instruction on the Answer sheet and insert the information required (including the subject code ) in the spaces provided 2. When told to open this book ,check that all the questions are there ,Look for the words' END OF PA PER ' after the last question 3. ANSWER ALL QUESTIONS sheet

.All the answers should be marked on the answer

4. Note that you may only mark ONE answer to each question . Two or more answers will score NO MARKS 5. All questions carry equal marks . no marks will be deducted for wrong answers There a re 50 q uestio ns in this paper

1. Which of the following diagrams can represent a mixture of two compounds? (In these diagrams , ● and ○ represent a nitrogen atom and an oxygen atom respectively.)

2. One mole of calcium bromide contains. A. 1 mole of molecules. B. 2 mole of cations. C. 2 mole of anions. D. 3 mole of atoms. 3. Which of the following substances has the lowest boiling point? A. ethanol. B. propan-1-o1 C. propane.

D. butane.

4. Element X and Element Y belong to the first three periods of the Periodic Table. The compound formed between these two elements has the following electronic structure:

(Only outermost shell electrons are shown.) How many electrons are there in the outermost shell of an atom of X and that of Y? X Y A. 1

3

B. 1

5

C. 2

8

D. 3

5

5. Consider the information concerning particle X and particle Y listed below: particle Number of protons X 16 Y 16

Number of electrons 16 18

Number of neutrons 18 18

Which of the following statements is correct?

A. X and Y are atoms of the same element. B. X and Y are atoms of different element. C. X is a cation of Y. D. Y is an anion of X. 6. The concentration of an aqueous solution of an acid is 1.0 M. 25.0 cm3 this acid solution requires 37.5 cm3 of 2.0 M sodium hydroxide solution for complete neutralization. What is the basicity of the acid? A. 1. B. 2. C. 3. D. 4.

7. Substance X gives identical product (s) when treated with dilute sulphuric acid or concentrated sulphuric acid. X may be. A. zinc. B. cane sugar. C. ammonia. D. hydrated copper (II) sulphate crystals. 8. Iron can be produced from iron (III) oxide by the following reaction: Fe2O3(s)+3CO(g)→2Fe(s)+3CO2(g) What mass of iron (III) oxide is required to by the following reaction:

(Relative atomic masses : O=16.0, Fe = 56.0) A. 3.0 g. B. 4.5 g. C. 6.0 g. D. 9.0 g. 9. In which of the following reactions is the underlined reactant reduced.? A. CU2 + + 2OH- → Cu(OH)2 B. SO2 + 2Mg → 2MgO + S C. 2NH3 +3CuO → 3Cu + N2+ 3H2O D. Zn + 2AgNO3 → Zn(NO3) +2Ag

10. Which of the following statements concerning bromine and chlorine is INCORRECT? A. They exist as diatomic molecules. B. Their atoms have the same number of outermost shell electronic. C. They form ions with a single negative charge. D. Bromine is a stronger oxidizing agent than chlorine. 11. The table below shows the ability of four substances W, X, Y and Z to conduct electricity.

(In the table, ˇ and × respectively represent ‘ can conduct electricity ‘ and ‘ cannot conduct electricity’.)

Which of the substances is likely to be zinc chloride? A. W. B. X. C. Y. D. Z. 12.

Consider the electrolysis experiment shown below: Which of the following statements concerning this experiment is correct? A. The mass of the impure copper rod decreases. B. The blue color of the copper (II) sulphate solution gradually fades off. C. Oxidation takes place at the pure copper rod.

D. The electrolysis process can enhance the corrosion resistance of copper

13. Which of the following irons is responsible for the yellow color of topaz? A. Ni2+. B. Fe3+. C. Cr3+. D. Mn3+. 14. Which of the following adverse affects associated with excessive intake of food additives is correct? Food additive A. tartrazine (a yellow coloring) B. sodium nitrite C. monosodium glutamate D. sodium chloride

Adverse effect causing hyperactivity. causing stomach ulcer. causing cancer. causing allergy.

15. Potassium permanganate solution acidified with dilute sulphuric acid is a commonly-used oxidizing agent. Dilute nitric acid is not used to acidify potassium permanganate solution because. A. nitric acid is more expensive than sulphuric acid. B. dilute nitric acid is an oxidizing agent than sulphuric acid. C. nitric acid decomposes more readily than sulphuric acid. D. dilute nitric acid would react with potassium permanganate solution

16. At room temperature and pressure, 8.0 g of oxygen and 20.0 g of gas X occupy the same volume. What is the molar mass of X? (Relative atomic mass : O=16.0; molar volume of gas at room temperature and pressure= 24.0 dm3) A. 20.0 g. B. 40.0 g. C. 60.0 g. D. 80.0 g. 17. The compound X2S contains 58.9 % of X by mass. What is the relative atomic mass of X ? (Relative atomic mass : S =32.1) A. 11.5. B. 23.0. C. 39.0. D. 46.0. 18. Which of the following processes would NOT produce hydrogen gas? A. adding calcium to water. B. adding magnesium to dilute nitric acid. C. adding copper to dilute nitric acid. D. passing steam over red hot iron. 19. Ionic compound X has the formula AB2, where A and B represent the cation and anion respectively. If both A and B have the same electronic arrangement, X may be A. potassium sulphide. B. magnesium fluoride. C. silicon dioxide. D. calcium bromide. 20. Which of the following solutions would produce a white precipitate with sodium hydroxide solution? A. lead (II) nitrate solution. B. iron (III) nitrate solution. C. copper (II)nitrate solution. D. potassium nitrate solution. 21. Consider the following chemical equation: 2HNO3 + xFeSO4 + yH2SO4 → zFe2(SO4)3 + 4H2O + 2NO

Which of the following combinations is correct? x y z A 2 1 1 B 4 3 2 C 6 2 3 D 6 3 3

22. In which of the following situations is iron prevented from rusting by sacrificial protection? A. Iron plates are jointed together with copper rivets. B. Iron pipes are connected to lead blocks. C. Iron sheets are plated with zinc. D. Iron cans are coated with tin. 23. Which of the following combinations is correct? Food additive Function A. Sodium Flavour benzoate enhancement B. Sugar Dehydration C. Monosodium sweetening glutamate D. Vinegar antioxidizing 24. In an experiment, sulphur dioxide is passed into an iodine solution which is prepared by dissolving some iodine in potassium iodine solution. Which of the following statements concerning this experiment is correct? A. The color of the iodine solution changes from purple to colorless. B. A brown solid is formed. C. A displacement reaction occurs. D. Sulphur dioxide is oxidized to sulphate ions 25. In an experiment , 1.00 M sodium hydroxide solution was added to 25.0 cm3 of 1.00 M sulphuric acid until the acid was completely neutralized. What is the concentration of sodium sulphate (correct to two decimal places) in the resulting solution? A. 1.00 M. B. 0.50. M. C. 0.33 M.

D. 0.5 M. Directions : Q.26 and Q.27 refer to the following experiment: Some concentrated sulphuric acid and pumice stones were added to an alkanol and an alkanoic acid. The mixture was heated under reflex for some time and the following compound was obtained:

26. Which of the following combinations is correct? Alkanol Alkanol acid A. Methanol Ethanoic acid B. Methanol Propanoic acid C. Ethanol Ethanoic acid D. Ethanol Propanoic acid 27. Which of the following statements concerning the experiment is correct? A. Concentrated sulphuric acid acts as an oxidizing agent in the reaction. B. The purpose of using pumice stones is to speed up the reaction. C. A fractionation column should be used in the experimental set-up. D. Heating under reflux can prevent the loss of reactants and products. 28. Which of the following substance is a thermoplastic as well as a condensation polymer ? A. nylon. B. Perspex. C. polyethene. D. urea-methanal. 29. Which of the following statements concerning household bleach is correct? A. The active ingredient of household bleach is sodium hydroxide. B. Household bleach is produced by dissolving chlorine in water. C. Household bleach can be used as a drain opener. D. The raw material for manufacturing household bleach is sodium chloride. 30. Which of the following combinations is INCORRECT? Pollutant Harmful effect A. Hydrocarbons Causing liver diseases

B. Carbon monoxide

Causing unconsciousnes s C. Lead compounds Causing brain damage D. Carbon particles Causing respiratory

31. Which of the following metal oxides CANNOT be reduced by heating with carbon? (1) magnesium oxide. (2) lead (II) oxide. (3) iron (III) oxide. A. (1) only. B. (2) only. C. (1) and (3) only. D. (2) and (3) only. 32. Which of the following substances can react with acidified potassium permanganate solution? (1) ethane. (2) copper (II) sulphate solution. (3) iron (II) sulphate solution. A. (1) only. B. (2) only. C. (1) and (3) only. D. (2) and (3) only. 33. Which of the following reactions will occur when aluminium powder is added to silver nitrate solution? (1). Displacement. (2) anodization. (3) redox. A. (1) only. B. (2) only. C. (1) and (3) only. D. (2) and (3) only.

34. Iodine is a solid at room temperature and pressure . Which of the following statements concerning the structure of iodine is/are correct?

(1) Iodine has a giant covalent structure. (2) Iodine molecules are held together by van der Waals’ forces. (3) Iodine atoms are held together in pairs by covalent bonds. A. (1) only. B. (2) only. C. (1) and (3) only. D. (2) and (3) only. 35. The label below is displayed on a container for chemical X:

Which of the following chemicals may X be? (1) bromochlorodifluoromethane. (2) ethanol. (3) potassium. A. (1) only. B. (2) only. C. (1) and (3) only. D. (2) and (3) only. 36. The equation below represents the reaction of chlorine with hot concentrated potassium hydroxide solution: 3Cl2(g) + 6KOH(aq) → 5KCl(aq) + KClO3(aq) + 3H2O(l) Which of the following statements concerning this reaction is/are correct? (1) Potassium hydroxide acts as a reduces agent. (2) The oxidation number of chlorine changes from 0 to –1. (3) The oxidation number of chlorine changes from 0 to +5. A. (1) only. B. (2) only. C. (1) and (3) only. D. (2) and (3) only. 37. Which of the following substances can react with magnesium to give a colorless which burns a ‘pop’ sound? (1) grapefruit juice.

(2) citric acid crystals. (3) household bleach. A. (1) only. B. (2) only. C. (1) and (3) only. D. (2) and (3) only. 38. Which of he following reactions is/are commonly stored in blown bottles? (1) potassium permanganate solution. (2) concentrated sulphuric acid. (3) concentrated nitric acid. A. (1) only. B. (2) only. C. (1) and (3) only. D. (2) and (3) only. 39. Element X has an isotope 3115X. Which of the following statements is/are correct? (1) X belongs to V of the Periodic Table. (2) X can react with oxygen to from an ionic compound. (3) 3115X has 16 neutrons. A. (1) only. B. (2) only. C. (1) and (3) only. D. (2) and (3) only. 40. Consider the following chemical cell:

Which of the following changes would lead to an increase in the voltage of the cell? (1) The zine electrode is replaced with a magnesium electrode. (2) The copper electrode is replaced with an iron electrode. (3) The sodium chloride solution is replaced with a sugar solution. A. (1) only. B. (2) only.

C. (1) and (3) only. D. (2) and (3) only. 41. Plastic X has the following structure:

Which of the following statements concerning X are correct? (1) The monomer of X is CHCI=CHCI. (2) X can be used to make electric sockets. (3) The flue gas produced by the incineration of X can cause the formation of acid rain. A. (1) and (2) only. B. (1) and (3) only. C. (2) and (3) only. D. (1),(2) and (3). 42. Consider the following experiment:

Which of the following statements concerning the experiment are correct? (1). Gas bubbles are evolved at electrode X. (2). An orange color gradually appears in the solution around electrode Y. (3). The experiment can be used to show that ions migrate towards oppositely charged electrodes. A. (1) and (2) only. B. (1) and (3) only. C. (2) and (3) only. D. (1),(2) and (3).

43. Which of the following statements concerning a soapless detergent are correct? (1). It can be prepared by heating a cooking oil with sodium hydroxide solution. (2) It acts as a wetting agent by reducing the surface tension of water. (3) It acts as an emulsifying agent in the cleaning process. A. (1) and (2) only. B. (1) and (3) only. C. (2) and (3) only. D. (1),(2) and (3). 44. Which of the following statements concerning the reaction of an alkane with bromine are correct? (1) The reaction occurs faster under sunlight than in darkness. (2) The reaction is a substitution. (3) The color of the reaction mixture fades. A. (1) and (2) only. B. (1) and (3) only. C. (2) and (3) only. D. (1),(2) and (3). Directions: Each question below (Question Nos. 45 to 50) consists of two separate statements . Decide whether each of the two statements is true or false; if both are true, then decide whether or not the second statement is a correct explanation of first statement. The select one option from A to D according to the following table: A. Both statements are true and the 2 nd statement is a correct explanation of the 1 st statement. B. Both statements are true but the 2 nd statement is NOT a correct explanation of the 1 st statement. C. The 1 st statement is false but the 2 nd statement is true. D. Both statements are false.

1 st statement 45. Sulphur is classified as a nonmetal.

2 nd statement Sulphur does not react with dilute acids.

46. Metals have Metals are good thermal composed of conductivity. giant lattices of positive ions surrounded by valence electrons which are free to move throughout the lattices. 47. Adding Potassium potassium nitrate can nitrate to soil provide the can increase form an crop yield. insoluble compound with soap. 48. Local tap Water water containing produces a calcium ions scum with can form an soap. insoluble compound with soap. 49. Water-type Water can cut fire off the supply extinguisher of oxygen for a is suitable for fire caused by putting out a kerosene. fire caused by kerosene. 50. Codeine , Codeine is which is an addictive. ingredient of some cough mixtures, may cause drowsiness. END OF PAPER KEYS 1. B 11. A 21. D 31. A 41. B 2. C 3. C

12. A 22. C 32. C 42. D 13. B. 23. B. 33. C 43. C

4. B 5. D 6. C 7. C 8. A 9. B 10 D

14. A. 15. B 16. D 17. B 18. C 19. B 20. A

24. D 25. C 26. B 27. D 28. A. 29. D 30. A

34. D 35. D 36. D 37. A 38. C 39. C 40. A

44. D 45. B 46. A. 47. A 48. C 49 D 50. B