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Chemistry 2009 PNEB (PUNTLAND NATIONAL EXAMINATION BOARD)

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  1. 1. Name ............................................................. School .................................. Roll Number.......................... Puntland State of Somalia Ministry of Education Puntland National Examination Board Form 4 CHEMISTRY Examination 2009 Time 2 hours Plus 10 minutes before the exam for reading through the paper TOTAL TIME 2 hours 10 minutes INSTRUCTIONS TO CANDIDATES INSTRUCTIONS TO CANDIDATES This paper consists of 20 printed pages Count them now. If there are any missing, inform the invigilator There are two parts: SECTION A Multiple Choice Questions 10 Marks SECTION B Structured Questions 90 Marks TOTAL 100 Marks Answer all questions All answers and working must be written on this paper in the spaces provided immediately after each question Rough work can be done on page 2. This will not be marked No extra paper is allowed No calculators are allowed If you make a mistake, cross out the incorrect answer and clearly write your correct answer
  2. 2. Puntland National Examination Board Secondary School Form Four Examinations Puntland Certificate of Education Chemistry Examination June 2009 PNEB, 20092 Use This Page for Rough Work, It Will Not Be Marked . . . .
  3. 3. Puntland National Examination Board Secondary School Form Four Examinations Puntland Certificate of Education Chemistry Examination June 2009 PNEB, 20093 SECTION A: MULTIPLE CHOICE QUESTIONS (10 MARKS) Instructions for this section: For each question in this section, circle the correct answer If you change your mind, cross out the wrongly chosen answer and clearly circle the correct answer For each question there is only one correct answer If the examiner thinks you have marked two answers, you will not receive a mark for that question. 1. Which of these reactions uses up oxygen? A Addition B Combustion C Polymerization D Cracking 2. Which of the following letters is correct for the symbol for Magnesium atom? A MG B Mg C mg D mG 3. What is the possible identity of the gases A and B in the experiment shown below? A Ammonia and Hydrogen B Ammonia and Hydrogen chloride C Ammonia and Nitrogen D Ammonia and Chlorine
  4. 4. Puntland National Examination Board Secondary School Form Four Examinations Puntland Certificate of Education Chemistry Examination June 2009 PNEB, 20094 4. What is the Percentage mass of hydrogen in methane (C H 4 A 25% B 45% ) gas? C 15% D 75% 5. The four tubes show an investigation of rusting. Each one of these four tubes contains a nail and the reagents indicated. In which tube would the nail rust first? A 1 B 4 C 3 D 2 6. In the reaction below, what is So2 2 Mg acting as? (s) + SO2 (g) 2 MgO (s) + S (s) A A catalyst B An oxidizing agent C An acid D A reducing agent
  5. 5. Puntland National Examination Board Secondary School Form Four Examinations Puntland Certificate of Education Chemistry Examination June 2009 PNEB, 20095 7. This box shows the reactivity of some elements. Which metal from the table above is most likely to be found uncombined in the earths crust? A Copper B Lead C Zinc D Magnesium 8. Which of the following is not true for ammonia? A It has a sharp or pungent smell B It can be collected over water C It turns universal indicator solution from green to blue D It is less dense than air 9. Chemical formula for Aluminium Sulphate is A AlSO4 B (Al) 2 SO4 C Al (SO4) D Al 3 2 (SO4)3 Magnesium Most Reactive Zinc Iron Increasing reactivity Tin Lead Copper Least Reactive
  6. 6. Puntland National Examination Board Secondary School Form Four Examinations Puntland Certificate of Education Chemistry Examination June 2009 PNEB, 20096 10. Study the diagram below and use it to answer the question. Solid W Liquid Gas What process is represented by letter W? A Evaporation B Sublimation C Freezing D Melting
  7. 7. Puntland National Examination Board Secondary School Form Four Examinations Puntland Certificate of Education Chemistry Examination June 2009 PNEB, 20097 SECTION B: STRUCTURED QUESTIONS (90 MARKS) Question 1 (10 marks) a) The diagrams below show the arrangement of particles in the three different states of water. A B C Identify what state each letter represents. (3 marks) A. B. C. b) Classify the following as either physical or chemical change. i. Fermentation of beer (1 mark) .. ii. Rusting of iron (1 mark) . iii. Dissolving of table salt (1 mark) . iv. Heating of ice (1 mark) .
  8. 8. Puntland National Examination Board Secondary School Form Four Examinations Puntland Certificate of Education Chemistry Examination June 2009 PNEB, 20098 c) A student extracted red colouring from four different plants, R, S, T, and U and put a spot of each colouring on a filter paper. The filter paper was dipped into a solvent and left for 30 minutes. See the results in the diagram below. i) What is the name given to the separation process shown in the diagram? (1 mark) . ii) Which plant contained the greatest number of different pigments? (1 mark) .. iii) Which two plants contained the same pigments? (1 mark)
  9. 9. Puntland National Examination Board Secondary School Form Four Examinations Puntland Certificate of Education Chemistry Examination June 2009 PNEB, 20099 Question 2 (7 marks) a) The diagram shows how paraffin oil vapour can be cracked (broken down) in the laboratory. i. What is the function of the aluminium oxide in this experiment? (1 mark) .. ii. Give one advantage of cracking paraffin. (1 mark)
  10. 10. Puntland National Examination Board Secondary School Form Four Examinations Puntland Certificate of Education Chemistry Examination June 2009 PNEB, 200910 iii. Two gases collected in the gas jar are displayed below. Identify them. (2 marks) H H H H H I I I I H---C-----C-----C----H C = C I I I I I H H H H H Gas A__________________ Gas B_________________ b) The equations below illustrate three typical reactions of alkanes. i. CH3 CH3 + Cl2 light CH3 CH2 Cl + HCl ii. 2 CH3 CH3 + 7 O 2 heat 4 CO 2 (g) + 6 H 2 O (l) iii. CH2 = CH2 + H2 Ni(s) CH3 CH 130 3 o C 150o C Name the type of reaction in each equation: (3 marks) i.. ii. iii. .. Question 3 (10 marks) a) Look at the pH scale below for some solutions found in the laboratory. i) What would be the pH value for a very strong acid? (1mark) ii) What would be the pH value for a very strong alkaline solution? (1 mark) 1 2 3 4 5 6 7 8 9 10 11 12 13 14
  11. 11. Puntland National Examination Board Secondary School Form Four Examinations Puntland Certificate of Education Chemistry Examination June 2009 PNEB, 200911 iii) What would be the pH value for a neutral solution? (1 mark) . b) Complete the following word equations i. Acid + Metal .. ... (2 marks) ii. Hydrochloric Acid + iron (2 marks) c) What is the concentration of 100 cm3 moles? (Na = 23, H = 1, O = 16) (3 marks) of a solution of sodium chloride containing 0.04 ... ... ...
  12. 12. Puntland National Examination Board Secondary School Form Four Examinations Puntland Certificate of Education Chemistry Examination June 2009 PNEB, 200912 Question 4 (7 marks) a) Ammonia is produced through the Haber process where conditions are designed to make it quickly and cheaply. Study the graph and answer the questions that follow. i. If the Haber process is carried out at 400o what percentage of ammonia will be at equilibrium? (1 mark) C, at a pressure of 200atm, approximately . ii. What effect does decreasing the temperature have on the yield of ammonia? (1 mark) . .
  13. 13. Puntland National Examination Board Secondary School Form Four Examinations Puntland Certificate of Education Chemistry Examination June 2009 PNEB, 200913 b) Nitrogen (II) oxide readily reacts with oxygen to form nitrogen (IV) oxide. The following is an energy-level diagram for the reaction. i. What does each of the following represent? (3 marks) H1 H 2 H3 ii. What is the sign on H3 . ? (1 mark) iii. Write an expression for H3 in terms of H1 and H2 . (1 mark) .
  14. 14. Puntland National Examination Board Secondary School Form Four Examinations Puntland Certificate of Education Chemistry Examination June 2009 PNEB, 200914 Question 5 (8 marks) Study the table below and use the information to answer the questions that follow: Substance Electrical Conductivity Melting point Boiling point 0 cSolid Molten In water A Good Good Does not dissolve 1540 2760 B Poor Poor Poor 0 100 C Poor Good Good 808 1465 D Good Good Makes an alkaline solution 98 890 a) Choose one metal which, at room temperature, (200 i. Solid (1 mark) C) is: ii. Liquid (1 mark) .. b) i. Which substance is an ionic compound? (1 mark) . ii. Give reasons to your choice. (2 marks) ... c) i. Which substance could be an element of group I metals? (1 mark) ii. Give reasons to your choice. (2 marks) ...
  15. 15. Puntland National Examination Board Secondary School Form Four Examinations Puntland Certificate of Education Chemistry Examination June 2009 PNEB, 200915 Question 6 (10 marks) The table below is about investigations of metal reactivity: Metal Solution to which metal is added Magnesium Chloride Iron Sulphate Lead Nitrate Copper (I) Sulphate Silver Nitrate Magnesium Iron X Lead X X X Copper X X X Silver X X X X Look at the table carefully and notice that: The cross ( X ) is used to show if a less reactive metal is displaced from solution. The tick ( ) is used to show if there is no reaction. a) Fill the table by putting ( ) or ( X ) in the appropriate blanks. (4 marks) b) An iron nail is placed in a Copper (II) Sulphate solution. The equation for the reaction is; Fe (s) + CU SO 4 (aq) Fe SO 4 (aq) + CU (s) i. Write an ionic equation for the reaction. (2 marks) ... ii. Write reduction half equation. (2 marks) ii. Write oxidation half equation. (2 marks)
  16. 16. Puntland National Examination Board Secondary School Form Four Examinations Puntland Certificate of Education Chemistry Examination Jun

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