1998 Paper 2

HONG KONG EXAMINATIONS QUTHORITY HONG KONG CERTIFICATE OF EDUCATION EXAMINATION 1998

CHEMISTRY PAPER II 10.45am-11.45am(1 hour ) 1. Read carefully 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 the all the questions are there ,Look for the words 'END OF PAPER ' after the last question 3. ANSWER ALL QUESTIONS .All the answers should be marked on the answer sheet 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 are questions in this paper . 1. An element X exists as molecules. X has an atomic number of 7 and a molecule of X has a formula X2 . Which of the following can represent the electronic structure of

X2 ? 2. The formula for ozone is O3. If one mole of ozone contains x atoms, how many atoms will atoms will one mole of oxygen gas contain? A. x/3. B. 2x/3. C. 3x/2. D. 3x. 3. Which of the following substance is the main constituent of town gas? A. hydrogen. B. methane. C. carbon monoxide. D. gaseous naphtha.

Directions: Questions 4 and 5 refer to the following experiment: The circuit shown below is set up and the solid lead (II) bromide is heated until it becomes molten.

4. Which of the following statements concerning the experiment is INCORRECT? A. The bulb lights up. B. A reddish brown gas is liberated at electrode X. C. Electrodes X and Y can be made of nichrome. D. Oxidation occurs at electrode Y. 5. Which of the following can be deduced from the experimental results? A. Solid lead (II) bromide contains mobile ions. B. Molten lead (II) bromide contains delocalized electrons. C. Molten lead (II) bromide can be decomposed by electricity. D. Solid lead (II) bromide is a convalent compound but molten lead (II) bromide is an ionic compound.

6. A part of the Periodic Table is shown below. Which of the following statements is correct? A. The outermost electron shell of an atom of a is an octet structure. B. The metallic character of the Period 2 elements increases from b to d . C. c forms an ionic compound with d. D. e is a strong oxidizing agent.

7. Which of the following environmental problems is NOT caused by excessive burning of fossil fuels? A. the corrosion of marble statues. B. the formation of smog. C. a higher incidence of liver diseases. D. global warning. 8. Monosodium glutamate is used A. to prevent food from being oxidized by air. B. to kill bacteria in food. C. to enhance the flavour of food. D. to improve the appearance of food. 9. Which of the following substances has a pH less than 7? A. lemon juice. B. soap solution. C. glass cleaner. D. milk of magnesia. 10. The formula for hydrated iron (II) sulphate is FeSO4‧xH2O. On strong heating, 20.1 g of the sulphate produces 9.1 g of water. What is the value of x? (Relative atomic masses: H=1.0, O=16.0, S=32.1, Fe=56.0) A. 5. B. 6. C. 7. D. 8. 11. Consider the following experiment.

During the experiment , a gas is liberated. The gas burn at the end of the delivery tube. X is probably A. copper. B. lead. C. silver.

D. zinc. 12.

A gas X is bubbled into a solution of Y as shown in the above diagram. In which of the following combinations would X react with Y ? X Y A. Ammonia Potassium nitrate B. Chlorine Potassium nitrate C. Carbon dioxide Sodium hydroxide D. Sulpur dioxide Iron (II) sulphate

13. In an experiment, 10 cm3 of 1 M hydrochloric acid is added slowly into 10 cm3 of 1 M sodium hydroxide solution . Which of the following statements concerning this experiment is correct? A. The temperature of the mixture increases. B. The pH of the mixture increases. C. The mixture does not conduct electricity at the end of the experiment. D. The concentration of sodium ions in the mixture remains unchanged. 14. Which of the following statements concerning propene is correct? A. It can be converted by catalytic hydration to an alkanol with molecular. B. It can undergo condensation poly . C. It can be manufactured by fractional distillation of crude oil D. It can undergo substitution reaction with a solution of bromine in 1, 1, 1trichloroethans. 15. A detergent has the following structure:

Which of the following statements concerning the detergent is correct? A. Its hydrocarbon chain is hydrophilic. B. It can be manufactured from vegetable. C. It is readily degraded by micro-organisms. D. It acts as an emulsifier in the cleaning process. 16. The formula of a solid dibasic acid is H2X. 2.88 g of the acid is dissolved in some distilled water and the solution is then diluted to 250.0 cm3 with distilled water . 25.0 cm3 of the diluted solution requires 16.0 cm3 of 0.40 M sodium hydroxide solution for complete neutralization. What is the molar mass of H2X.? A. 22.5 g B. 45.0 g. C. 90.0 g. D. 180.0 g. 17. Which of the following statements concerning the compounds C2H4, C3H6, and C4H10 is correct? A. They belong to the same homologous series. B. They are unsaturated hydrocarbon. C. They are gases at room temperature and pressure. D. They have the same physical properties. 18. Which of the following ions has the same number of protons as the hydroxide ion, OHA. O2B. FC. Na+ D. Mg2+ 19. In each of the four solutions shown below, a strip of zinc is added.

Which of the following combinations is correct? T Observation ube A. Ⅰ No change B. Ⅱ Brown coating on zinc C. Ⅲ No change D. Ⅳ Grey coating on zinc

20. The following equation represents the reaction of an oxide of lead with hydrogen: Pb3O4 (s) + 4H2(g) → 3Pb(s) + 4H2O(l) What mass of lead would be obtained if 68.5 g of the oxide was consumed in the reaction? (Relative atomic masses: O=16.0 ,Pb=207.0) A. 20.7 g. B. 41.4 g. C. 62.1 g. D. 82.8 g. 21. Consider the following experiment.

Which of the following statements concerning the above experiment is correct? A. Permanganate ions migrate into the salt bridge. B. Electrons flow from electrode X to electrode Y in the external circuit. C. Carbon electrodes are used because they are chemically inert. D. The half equation for the change occurring at electrode Y is Fe2+ + 2e- → Fe. 22. In Which of the following reactions does the underlined substance act as a reducing agent?

A. SO2 + 2H2S → 2S + 2H2O. B. Pb(NO3)2 + H2SO4 → PbSO4 + 2HNO3 C. 2HCl + MgO → MgCl2 + H2O D. 2KBr + Cl2 → 2KCl + Br2. 23. Which of the following is NOT the appropriate substance for preparing zinc sulphate by directly mixing with dilute sulphuric acid? A. zinc. B. zinc carbonate. C. zinc hydroxide. D. zinc nitrate. 24. Consider the following manufacturing process:

Which of the following graphs (not drawn to scale) can represent the change in relative molecular masses of the substances involved during the manufacturing process?

25. Dilute sodium hydroxide solution is added successively to four different solutions. Which of the following combinations is correct? Solution Observation A. Ammonium White chloride B. Lead (II) Yellow nitrate C. Potassium Orange dichromate

D. Iron (III) sulphate

Brown precipitate

26. Some physical properties of a compound X are listed below: melting point : 82 ℃ boiling point : 221 ℃ solubility in water : soluble Which of the following is the most appropriate method to obtain X from a solution of X in water ? A. decantation. B. crystallization. C. fractional distillation. D. paper chromatography. 27. Consider the following chemical equation: Zn + PMnO2 + qNH4+ → Zn2+ + xMn2O3 + yNH3 + zH2O Which of the following combinations is correct? x y z A. 1 2 1 B. 1 3 2 C. 2 3 2 D. 2 2 3 28. 7.5 g of calcium carbonate is added to 50.0 cm3 of 2 M hydrochloric acid. What is the volume of carbon dioxide liberated at room temperature and pressure? (Relative atomic masses: C=12.0, O=16.0, Ca=40.0; molar volume of gas at room temperature and pressure=24.0 dm3) A. 0.9 dm3 B. 1.2 dm3 C. 1.8 dm3 D. 2.4 dm3 29 .X is a compound containing four carbon atoms. It gives negative results with the following tests. Test (1) Treating X with sodium hydrogencabonate solution. (2) Treating X with a solution of bromine in 1, 1, 1-trichloroethane. (3) Heating X with acidified potassium dichromate solution. The structure formula of X may be. A. CH3CH2CH=CH2.

B. CH3CH2CH2CH2OH. C. CH3CH2CH2CO2H. D. CH3CH2CH2CH3. 30. Which of the following steps is NOT included in the Contact Process for the manufacture of sulphuric acid? A. burning sulphur in air to form sulphur dioxide. B. oxidizing sulphur dioxide to form sulphur reioxide C. dissolving sulphur reioxide in water to form oleum. D. mixing oleum with water to form concentrated sulphuric acid. 31. What is the propose of adding quicklime (calcium oxide) to soil? A. to neutralize the acidity of the soil. B. to act as a fertilizer for the soil. C. to kill micro-organisms in the soil. D. to increase the amount of calcium ions in the soil. 32. Which of the following combinations in correct? Sulphur Chlorine bleach dioxide bleach A. The active The active ingredient is ingredient is SO42+(aq) OCl-(aq) B. It bleaches by It bleaches by oxidation reduction C. Its bleaching Its bleaching action is action is slower faster D. Its bleaching Its bleaching effect is effect is temporary relatively longlasting. 33. Consider the following information : Substance Melting Electrical Solubility point conductivit in water /℃ y at room temperature W -34 poor Slightly soluble X 44 Poor Insoluble Y 232 Good Insoluble Z 782 Poor Very soluble

Which if the above substances exists as a simple mol solid at room temperature? A. W. B. X. C. Y. D. Z. 34. Which of the following substances is/are the main product (s) when a mixture of ammonia and oxygen is passed over red-hot platinum? (1) nitrogen. (2) nitrogen monoxide. (3) nitric acid. A. (1) only. B. (2) only. C. (1) and (3) only D. (2) and (3) only 35. Which of the following statements concerning cigarette smoking is/are correct? (1) Tar in cigarette smoke is addictive. (2) Nicotine in cigarette smoke causes high blood pressure. (3) Carbon monoxide in cigarette smoke can be removed by smoking cigarettes with filters. A. (1) only. B. (2) only. C. (1) and (3) only D. (2) and (3) only 36. Whic1 statements concerning polystyrene is/are correct? (1) It is a condensation polymer. (2) It can be remoulded. (3) It can be used to make packaging material for electrical appliances. A. (1) only. B. (2) only. C. (1) and (3) only D. (2) and (3) only 37. The following information is related to the manufacture of ammonia: Echem9811 Which of the following statements can be deduced from the above information? (1) Heat is liberated when ammonia is formed. (2) Ammonia decomposes to give nitrogen and hydrogen in the reaction chamber.

(3) A catalyst should be used. A. (1) and (2) only B. (1) and (3) only C. (2) and (3) only D. (1),(2) and (3) 38. Which of the following experiments would produces sulphur dioxide ? (1) heating iron pyrites in air. (2) heating a mixture of iron and dilute sulphuric acid. (3) heating a mixture of copper and concentrated sulphuric acid. A. (1) and (2) only B. (1) and (3) only C. (2) and (3) only D. (1),(2) and (3) 39. The diagram below shows a catalytic converter fitted to the exhaust system of a car.

Which of the following pollutants from the car engine undergo reactions in the catalytic converter to produce less harmful products? (1) carbon monoxide. (2) hydrocarbons. (3) nitrogen monoxide. A. (1) and (2) only B. (1) and (3) only C. (2) and (3) only D. (1),(2) and (3) 40. Brass is commonly used for making ornaments because (1) it has an attractive appearance. (2) it can resist corrosion. (3) it is softer than copper. Which of the following combinations is correct? A. (1) and (2) only

B. (1) and (3) only C. (2) and (3) only D. (1),(2) and (3) 41. Which of the following problems are associated with the excessive use of soapless detergents? (1) They can cause skin allergies. (2) They form foam when discharged into rivers and lakes. (3) They form scum when discharged into the sea. A. (1) and (2) only B. (1) and (3) only C. (2) and (3) only D. (1),(2) and (3) 42.

Which of the following statements concerning the gas produced in the above experiment are correct? (1) It is toxic. (2) It is readily soluble in 1, 1, 1-trichloroethane. (3) It can turn red litmus solution blue and then colorless. 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 substances are commonly found in canned grapefruit juice? (1) citric acid. (2) benzoic acid. (3) ethanoic acid.

A. (1) and (2) only B. (1) and (3) only C. (2) and (3) only D. (1),(2) and (3) 44. Upon heating , a mixture of iron and sulphur gives a black substance. Which of the following statements concerning the black substance are correct? (1) It is insoluble in water. (2) It can be attracted by a bar magnet. (3) It reacts with dilute hydrochloric acid to give a gas with a pungent smell. 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 2 nd statement 45. Element X Each atom of (atomic X loses one number 11) electron and reacts with each atom of Y element Y accepts two (atomic electrons to number 16) to form a form an ionic compound compound. with formula

X2Y 46. One mole of One mole of water occupies water contains the same the same volume as one number of mole of carbon atoms as one dioxide at room mole of carbon temperature and dioxide. pressure. 47. The use of Lead leaded petrol compounds in has been car exhaust can banned in Hong cause damage Kong to human brains. 48. The ethanol Beer is made by content of beer fermentation of is less than that barely while red of red wine. wine is made by fermentation of grapes. 49. Wash bottles used in the chemistry laboratory are commonly made of polyethene. 50. Paracetamol is a common active ingredient in anti-acids.

Polyethene is an addition polymer.

Paracetamol can netralize hydrochloric acid in the stomach.

END OF PAPER KEYS 1. D 11. D 21. C 31. A 41. A 2. B 3. A 4. B

12. C 22. D 32. D 42. A 13. A. 23. D. 33. B 43. A 14. A. 24. D 34. B 44. B

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

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

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

35. B 36. D 37. A 38. B 39. D 40. A

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