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Chemistry 2009 PNEB (PUNTLAND NATIONAL EXAMINATION BOARD)
- 1. Name ............................................................. School ..................................………………… RollNumber.........................…………………. 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. Puntland National ExaminationBoard 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. Puntland National ExaminationBoard 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. Puntland National ExaminationBoard 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. Puntland National ExaminationBoard 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 earth’s 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. Puntland National ExaminationBoard 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. Puntland National ExaminationBoard 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. Puntland National ExaminationBoard 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. Puntland National ExaminationBoard 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. Puntland National ExaminationBoard 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 Ι 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. Puntland National ExaminationBoard 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. Puntland National ExaminationBoard 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. Puntland National ExaminationBoard 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) ΔH1 ΔH ………………………………………………………………………… 2 ΔH3………………………………………………………………………… ………………………………………………………………………… ii. What is the sign on ΔH3 …………………………………………………………………………………………………. ? (1 mark) iii. Write an expression for ΔH3 in terms of ΔH1 and ΔH2 …………………………………………………………………………………………………. (1 mark) ………………………………………………………………………………………………….
- 14. Puntland National ExaminationBoard 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. Puntland National ExaminationBoard 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. Puntland National ExaminationBoard Secondary School Form Four Examinations Puntland Certificate of Education Chemistry Examination June 2009 ©PNEB, 200916 Question 7 (10 marks) Carbon exists in two crystalline allotropic forms shown in the diagram below. I II a. i) Name the allotropes labeled (2 marks) I………………………………………………… II………………………………………………… ii) Give one use of the allotrope in (I) above. (1 mark) ……………………………………………………………………………………………………… ………………………………………………………………………………………... iii) Which allotrope has its carbon atoms bonded to four other carbon atoms? (1 mark) …………………………………………… b) Give reason(s) for the following statements, identifying in each case, the allotrope being referred to. i. One allotrope conducts electricity while the other does not. (2 marks) ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ……………………………………………………………………………………………………... ……………………………………………………………………………………………………... ii. One allotrope is soft and slippery while the other is very hard. (2 marks) ……………………………………………………………………………………………………… ……………………………………………………………………………………………………... ………………………………………………………………………………………………………
- 17. Puntland National ExaminationBoard Secondary School Form Four Examinations Puntland Certificate of Education Chemistry Examination June 2009 ©PNEB, 200917 iii. One allotrope has a lower density than the other. (2 marks) ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ……………………………………………………………………………………………………... Question 8 (11 marks) This diagram shows the apparatus used to find out the effect of an electric current on a concentrated aqueous solution of sodium chloride. a) i. What is electrolysis? (2 marks) ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ……………………………………………………………………………………………………... ii. On the diagram label the electrodes. (2 marks) b) State three things you will observe when the circuit is switched on. (3 marks) ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ……………………………………………………………………………………………………... ……………………………………………………………………………………………………... c) i. Name the product at the positive electrode. (2 marks) ………………………………………………………………..
- 18. Puntland National ExaminationBoard Secondary School Form Four Examinations Puntland Certificate of Education Chemistry Examination June 2009 ©PNEB, 200918 ii. State a test for this product and the result of the test. (2 marks) ……………………………………………………………………………………………………… ……………………………………………………………………………………………………... Question 9 (7 marks) a) The diagram below shows part of periodic table. The letters do not represent the actual symbols elements. a b d e f i. Which element is in group 4? (1 mark) ……………………………………………………….. ii. Which element is in the second period? (1 mark) ……………………………………………………… iii. Which element is a noble gas? (1 mark) ………………………..…………………………….. iv. Which element is a metalloid? (1 mark) ……………………………………………………. v. Give two (2) elements that are non-metals? (2 marks) ……………………………………………………. vi. Which element is likely to be a gas? (1 mark) ……………………………………………………
- 19. Puntland National ExaminationBoard Secondary School Form Four Examinations Puntland Certificate of Education Chemistry Examination June 2009 ©PNEB, 200919 Question 10 (10 marks) Ali collected some water from a polluted river. The water contained soluble solids and insoluble clay and had a pH of 5. a) How can Ali separate the clay from the rest of the river water? (1 mark) ………………………………………………………………………….. b) What will be the effect of this water on litmus paper? (1 mark) ………………………………………………………………………….. c) Ali then boiled the river water to obtain the soluble solids. The diagram below shows how he heated the water. Which of the substances named in the diagram is i. an alloy? (1 mark) ……………………………………………………………… ii. a compound which is liquid at room temperature? (1 mark) ……………………………………………………………… iii. an element? (1 mark) ………………………………………………………………. iv. a fuel? (1 mark) ………………………………………………………………
- 20. Puntland National ExaminationBoard Secondary School Form Four Examinations Puntland Certificate of Education Chemistry Examination June 2009 ©PNEB, 200920 d) Name the main substance in natural gas? (1 mark) ……………………………………………………………… e) What is the normal temperature of boiling water? (1 mark) ……………………………………………………………… f) After Ali boiled off the water, he analysed the white powder on the inside of the steel can. The table shows his results. Name of ion Formula of ion Mass of ion present / milligrams Calcium Ca 162+ Carbonate CO3 352- Chloride Cl 8- Nitrate NO3 4- Sodium Na 8+ Sulphate SO4 62- i. Which positive ion had the greatest concentration in the sample of river water? ………………………………………………………………… (1 mark) ii. Complete the following equation to show how a sodium ion is formed. Na Na+ + …………………. (1 mark) END