Cambridge IGCSE Science - Combined 0653 — 2010 Oct/Nov Paper 5 · Variant 1

This document consists of 8 printed pages and 4 blank pages. IB10 11_0653_51/3RP © UCLES 2010 [Turn over *5830096724* For Examiner's Use 1 2 3 Total UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS International General Certificate of Secondary Education COMBINED SCIENCE 0653/51 Paper 5 Practical Test October/November 2010 1 hour 30 minutes Candidates answer on the Question Paper. Additional Materials: As listed in Instructions to Supervisors. READ THESE INSTRUCTIONS FIRST Write your Centre number, candidate number and name on all the work you hand in. Write in dark blue or black pen. You may use a pencil for any diagrams, graphs or rough working. Do not use staples, paper clips, highlighters, glue or correction fluid. DO NOT WRITE IN ANY BARCODES. Answer all questions. Chemistry practical notes for this paper are printed on page 8. At the end of the examination, fasten all your work securely together. The number of marks is given in brackets [ ] at the end of each question or part question. www.XtremePapers.com

2 © UCLES 2010 0653/51/O/N/10 For Examiner's Use 1 This question is about the diseases kwashiorkor and diabetes, and how changes in the diet can help sufferers. (a) Kwashiorkor is caused by lack of protein in the diet. You have five solutions, A to E. Two of these contain protein that may help a kwashiorkor sufferer, if they are included in the diet. (i) Test A to E with biuret solution. Use about 2 cm3 of the test solution, using a clean test-tube each time. Add an equal volume of biuret to each tube. Record your results in Table 1.1. [2] Table 1.1 colour observed solution biuret solution iodine solution Benedict’s solution A B C D E (ii) Which solutions contained protein? and [1] (b) Sufferers of diabetes are often advised to have their carbohydrate in the form of starch rather than sugar. (i) Test the three solutions that do not contain protein to find which one contains starch. Place about 2 cm3 of the solution into a test-tube and add a few drops of iodine. Use a clean test-tube each time. Record your observations in Table 1.1. [2] (ii) Which solution contained starch? [1]

3 © UCLES 2010 0653/51/O/N/10 [Turn over For Examiner's Use (c) You should now have two solutions which do not contain either protein or starch. One of these contains glucose. Diabetics should avoid eating large amounts of glucose. (i) Test these two solutions for the reducing sugar, glucose, as follows. To about 2 cm3 of the solution add an equal volume of Benedict’s solution. Place the tube in a hot water bath for a few minutes. Record your observations in Table 1.1. [1] (ii) Which solution contained glucose? [1] (d) One of the two protein solutions that you have identified in part (a)(ii) contains the enzyme amylase. When starch solution is allowed to react with amylase for five minutes at room temperature, it is broken down to a reducing sugar. Plan an experiment to find which of the two protein solutions contains the enzyme. [2]

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5 © UCLES 2010 0653/51/O/N/10 [Turn over For Examiner's Use 2 A student made the following statement. “When two lamps are connected in series, the total power output is half that for a single lamp.” You are going to test the correctness of this statement by carrying out the following experiment. Set up the circuit as shown in Fig. 2.1. A V Fig. 2.1 (a) Close the switch. Measure and record in Table 2.1 the current and the potential difference in the circuit together with each unit. Open the switch. [3] (b) Disconnect the voltmeter. Connect the second lamp in series with the first as shown in Fig. 2.2. A V Fig. 2.2 Connect the voltmeter across both lamps. Close the switch. Measure the current and potential difference in the circuit with both lamps connected. Record these values in Table 2.1. Open the switch.

6 © UCLES 2010 0653/51/O/N/10 For Examiner's Use Table 2.1 current potential difference power = current value x p.d. value unit = unit = unit = single lamp 2 lamps in series Power is the product of the voltage and current. Complete Table 2.1 by calculating the values of power. [1] (c) Use the values from (b) to make your comment on the statement “When two lamps are connected in series, the total power output is half that for a single lamp,” made by the student. [2] A second student made the following statement. “When two lamps are connected in parallel, the total power output is double that for a single lamp.” You are going to test the correctness of this statement.

7 © UCLES 2010 0653/51/O/N/10 [Turn over For Examiner's Use (d) Connect the two lamps in parallel. Connect the voltmeter as shown in Fig. 2.3. A V Fig. 2.3 Close the switch and measure the current and potential difference. Record these values in Table 2.2. Open the switch. Table 2.2 current potential difference power = current value x p.d. value unit = unit = unit = single lamp 2 lamps in parallel Complete Table 2.2 by calculating the power. Remember that you have already found the potential difference and the current for a single lamp. [2] (e) Using the values you have calculated in Table 2.2 for the power produced by two lamps in parallel, comment on the statement “When two lamps are connected in parallel, the total power output is double that for a single lamp,” made by the second student. [2]

8 © UCLES 2010 0653/51/O/N/10 For Examiner's Use 3 Compound X dissolves in water to give a solution containing three different ions. Carry out the following tests to identify these three ions. Divide compound X into three equal portions. (a) Heat strongly one portion of X in a hard glass test-tube for several minutes. After the water vapour has been given off, continue heating until no further change. Allow to cool. Record your observations. changes to solid [3] (b) To a second portion of X, add about 2 cm3 of aqueous sodium hydroxide and warm gently. Test any gas with litmus paper. Record your observations. litmus paper name of gas [2] (c) Dissolve the third portion of X in 10 cm3 water and divide the solution into two parts. (i) To one part, add about 3 cm3 aqueous sodium hydroxide. Record the colour of the precipitate. colour of precipitate [1] (ii) Using the second part of the solution of X, add dilute hydrochloric acid, followed by aqueous barium chloride. Record your observations. [1] (d) Name the three ions in compound X. 1 2 3 [3]

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12 Permission to reproduce items where third-party owned material protected by copyright is included has been sought and cleared where possible. Every reasonable effort has been made by the publisher (UCLES) to trace copyright holders, but if any items requiring clearance have unwittingly been included, the publisher will be pleased to make amends at the earliest possible opportunity. University of Cambridge International Examinations is part of the Cambridge Assessment Group. Cambridge Assessment is the brand name of University of Cambridge Local Examinations Syndicate (UCLES), which is itself a department of the University of Cambridge. © UCLES 2010 0653/51/O/N/10 CHEMISTRY PRACTICAL NOTES Test for anions anion test test result carbonate (CO3 2-) add dilute acid effervescence, carbon dioxide produced chloride (Cl -) [in solution] acidify with dilute nitric acid, then add aqueous silver nitrate white ppt. nitrate (NO3 -) [in solution] add aqueous sodium hydroxide then aluminium foil; warm carefully ammonia produced sulfate (SO4 2-) [in solution] acidify then add aqueous barium chloride or aqueous barium nitrate white ppt. Test for aqueous cations cation effect of aqueous sodium hydroxide effect of aqueous ammonia ammonium (NH4 +) ammonia produced on warming - copper(II) (Cu2+) light blue ppt., insoluble in excess light blue ppt., soluble in excess giving a dark blue solution iron(II) (Fe2+) green ppt., insoluble in excess green ppt., insoluble in excess iron(III) (Fe3+) red-brown ppt., insoluble in excess red-brown ppt., insoluble in excess zinc (Zn2+) white ppt., soluble in excess giving a colourless solution white ppt., soluble in excess giving a colourless solution Test for gases gas test and test results ammonia (NH3) turns damp red litmus paper blue carbon dioxide (CO2) turns limewater milky chlorine (Cl2) bleaches damp litmus paper hydrogen (H2) “pops” with a lighted splint oxygen (O2) relights a glowing splint

UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS International General Certificate of Secondary Education MARK SCHEME for the October/November 2010 question paper for the guidance of teachers 0653 COMBINED SCIENCE 0653/51 Paper 5 (Practical Test), maximum raw mark 30 This mark scheme is published as an aid to teachers and candidates, to indicate the requirements of the examination. It shows the basis on which Examiners were instructed to award marks. It does not indicate the details of the discussions that took place at an Examiners’ meeting before marking began, which would have considered the acceptability of alternative answers. Mark schemes must be read in conjunction with the question papers and the report on the examination. • CIE will not enter into discussions or correspondence in connection with these mark schemes. CIE is publishing the mark schemes for the October/November 2010 question papers for most IGCSE, GCE Advanced Level and Advanced Subsidiary Level syllabuses and some Ordinary Level syllabuses. www.XtremePapers.com

Page 2 Mark Scheme: Teachers’ version Syllabus Paper IGCSE – October/November 2010 0653 51 © UCLES 2010 1 (a) (i) entered in Table 1.1 A, B, D blue ; C, E purple ; [2] (ii) C and E ; [1] (b) (i) entered in Table 1.1 B, blue / black ; A, D brown / yellow / orange ; [2] (ii) solution B ; [1] (c) (i) entered in Table 1.1 A, blue ; D, red / orange ; [1] (ii) (solution) D ; [1] (d) add both protein solutions to starch solution ; test with Benedict’s solution amylase produces a positive result for reducing sugar ; [2] [Total: 10] 2 (a) in Table 2.1 sensible readings for current (less than 1 A) and voltage ; current is about half when both lamps connected ; voltage is about the same (+/– 10 %) ; [3] (b) product of p.d. and current is correct for figures ; [1] (c) statement fits results ; the results confirm the original statement ; (only 1 mark if candidate fails to recognise correct answer) [2] (d) current is greater than when 1 lamp used ; units correct in either table ; [2] (e) statement fits results ; the results confirm the original statement ; (allow 1 mark if results ‘do not fit’ and the correct reasoning is also given). [2] [Total: 10]

Page 3 Mark Scheme: Teachers’ version Syllabus Paper IGCSE – October/November 2010 0653 51 © UCLES 2010 3 (a) solid turns white ; then brown (black acceptable) ; white smoke ; (allow reference to sulfur dioxide / sublimation in lieu of marks allocated to change of solid) [3] (b) litmus blue ; ammonia ; [2] (c) (i) green ; [1] (ii) white ppt. ; [1] (e) iron(II) ; ammonium ; sulfate ; (one mark for each) [3] [Total: 10]