WDL 4NA Science Chemistry P4 Question Booklet 2023

5105 and 5107/04/Prelim/2023 NORMAL (ACADEMIC) NORMAL (ACADEMIC) NORMAL (ACADEMIC) Name: ........................................................................ ( ) Class: ................ WOODLANDS SECONDARY SCHOOL PRELIMINARY EXAMINATIONS 2023 Level: Secondary Four Normal (Academic) Marks: 30 Subject: Science (Chemistry) Day: Wednesday Paper: 5105/04 and 5107/04 Date: 2 August 2023 Duration: 1 hour 15 minutes (Papers 3 and 4) Time: 1145 – 1300 READ THESE INSTRUCTIONS FIRST Write your class, index number and name on all the work that you hand in. Write in dark blue or black pen on both sides of the paper. You may use an HB pencil for any diagrams or graphs. Do not use staples, paper clips, glue or correction fluid. Answer all questions in Section A and any two questions in Section B. The use of an approved scientific calculator is expected, where appropriate. In calculations, you should show all the steps in your working, giving your answer in each stage. You are advised to spend no longer than 30 minutes on Paper 3. You may proceed to answer Paper 4 as soon as you have completed Paper 3. A copy of the Periodic Table is printed on page 12. At the end of the examination hand in your answers to Paper 3 and Paper 4 separately. The number of marks is given in brackets [ ] at the end of each question or part question. DO NOT TURN THE PAGE UNTIL YOU ARE TOLD TO DO SO. This document consists of 11 printed pages and 1 blank page. FOR EXAMINER’S USE Paper 3 Paper 4 Total /20 Section A /14 /30 /50 Section B /16

2 5105 and 5107/04/Prelim/2023 NORMAL (ACADEMIC) NORMAL (ACADEMIC) NORMAL (ACADEMIC) Section A Answer all questions in this section in the spaces provided. 1 The following table shows some substances, with their chemical formulae. substance chemical formula ammonia NH3 hydrogen H2 potassium hydroxide KOH propane C3H8 propene C3H6 sulfuric acid H2SO4 From the table, identify one substance which (a) decolourises reddish-brown aqueous bromine, ……………………………………………………………………………………..… [1] (b) extinguishes the flame on a lighted splint with a ‘pop’ sound, ……………………………………………………………………………………..… [1] (c) reacts with ammonium sulfate to produce ammonia gas, (d) ……………………………………………………………………………………..… [1] turns Universal Indicator red. ……………………………………………………………………………………….. [1]

3 5105 and 5107/04/Prelim/2023 NORMAL (ACADEMIC) NORMAL (ACADEMIC) NORMAL (ACADEMIC) 2 (a) Name the homologous series whose members undergo substitution reaction, and give the general formula for its members. homologous series: ……………………………………………………… [1] general formula: …………………………………………………………. [1] (b) State the name of the third member of the homologous series in part (a). Calculate its relative molecular mass and draw its structural formula. name of third member: ………………………………………………….. [1] relative molecular mass, Mr = [1] structural formula: [1] (c) For the substance you named in part (b), write a balanced chemical equation for its combustion reaction with oxygen. State symbols are not required. …………………………………………………………………………………… [1]

4 5105 and 5107/04/Prelim/2023 NORMAL (ACADEMIC) NORMAL (ACADEMIC) NORMAL (ACADEMIC) 3 (a) Complete the following table. atom nucleon number proton number number of protons number of electrons number of neutrons magnesium 24 12 fluorine 9 10 [2] (b) Draw a ‘dot and cross’ diagram to show the bonding in the compound formed by magnesium and fluorine. Show only the outermost shell electrons. [2]

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6 5105 and 5107/04/Prelim/2023 NORMAL (ACADEMIC) NORMAL (ACADEMIC) NORMAL (ACADEMIC) Section B Answer any two questions in this section in the spaces provided. 4 A student sets up the apparatus as shown below. Hydrochloric acid was added 5 cm 3 at a time to the beaker of aqueous potassium hydroxide. This was continued until 35.00 cm3 of acid had been added. The mixture was stirred and the temperature taken after the addition of each 5 cm 3 of acid. The results obtained are shown below. volume of acid / cm3 temperature of mixture / oC 0.00 20 5.00 26 10.00 31 15.00 35 20.00 38 25.00 32 30.00 25 35.00 21 (a) Name the piece of apparatus labelled T. ………………………………………………………………………………………… [1]

7 5105 and 5107/04/Prelim/2023 NORMAL (ACADEMIC) NORMAL (ACADEMIC) NORMAL (ACADEMIC) (b) (i) (ii) On the grid below, plot the values of temperature (y-axis) against the volume of acid (x-axis). Mark each point with a cross (x). Draw a best-fit straight line for the first four points and another best -fit straight line for the next four points. Extend the lines so that they intersect (cross) with each other. [2] From the graph above, state the highest temperature that the mixture will be able to reach. …………………………………………………………….…………………. [1] (c) The product of the reaction between hydrochloric acid and potassium hydroxide is potassium chloride and water. The chemical equation represents the reaction. KOH (………) + HCl (………) → KCl (……...) + H2O (……….) (i) Include the correct state symbols in the chemical equation above. [1] (ii) Write an ionic equation for the reaction. …..………………………………………………………………………….. [1] (d) Name the type of oxides that can react with both acids and alkalis. Give the chemical formula of one such oxide. Type of oxide: …………………………………….. [1] Chemical formula: ………………………………... [1]

8 5105 and 5107/04/Prelim/2023 NORMAL (ACADEMIC) NORMAL (ACADEMIC) NORMAL (ACADEMIC) 5 (a) Xebium, X, is a newly discovered element. It has the properties listed below: • It is a solid at room temperature. • It can be cut easily by a steel knife. • It reacts explosively with cold water to form a colourless gas. • It is also a good conductor of electricity. (i) In which Group of the Periodic Table would you expect to find Xebium? ………………………………………………..……………………………….. [1] (ii) State how you would store a sample of Xebium. ………………………………………………..……………………………….. [1] (b) (iii) (i) Write a balanced chemical equation for the reaction of Xebium with cold water. State symbols are not required. ………………………………………………..……………………………….. [1] Silver chloride is an insoluble salt that can be prepared by precipitation reaction between silver nitrate solution and sodium chloride solution. The diagram below shows how silver chloride can be separated from the mixture. Label the “residue” and the “filtrate” in the diagram below. State the name of the separation method. Name of method: ………………………… [2] (ii) Explain why solid silver chloride cannot conduct electricity at room temperature and pressure. ……………………………………………………………………………………... ………………………………………………………………………………… [1] filter funnel

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