Cambridge IGCSE Science - Combined 0653 — 2011 Oct/Nov Paper 5 · Variant 2

This document consists of 10 printed pages and 2 blank pages. IB11 11_0653_52/4RP © UCLES 2011 [Turn over *0007144459* For Examiner's Use 1 2 3 Total UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS International General Certificate of Secondary Education COMBINED SCIENCE 0653/52 Paper 5 Practical Test October/November 2011 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 12. 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 2011 0653/52/O/N/11 For Examiner's Use 1 You are going to investigate what affects the diffusion of hydrochloric acid into agar. You are provided with an agar block (of dimensions 20 mm x 10 mm x 10 mm) that contains phenolphthalein indicator and an alkali. Phenolphthalein is purple in pH greater than 8 and colourless in pH less than 8. (a) (i) ● Cut the agar block in half, producing two blocks of size 10 mm x 10 mm x 10 mm (as shown in Fig. 1.1). ● Keep one of these blocks intact (this is block A) and cut the other in half again (as shown in Fig. 1.1). ● Keep one of these blocks intact (this is block B) and cut the other in half again. Discard one of these (as shown in Fig. 1.1.) The remaining block is block C. ● You will now have three agar blocks of different surface areas. ● Label the test-tubes A, B, and C. ● Place about 20 cm3 of dilute hydrochloric acid in each of the three test-tubes A, B and C. ● Using tweezers, drop each block into separate test-tubes (as shown in Fig. 1.1) as quickly as possible and start the stopclock. ● Record the time taken, in Table 1.1, for each block to go completely colourless (as shown in Fig. 1.2). [3] While you are waiting for the blocks to become colourless, you can be performing the calculations needed to complete Table 1.1.

3 © UCLES 2011 0653/52/O/N/11 [Turn over For Examiner's Use 20 mm 10 mm 10 mm 10 mm 10 mm 10 mm 10 mm 10 mm 10 mm cut on dotted line cut on dotted line cut on dotted line test tube A 5 mm 10 mm 10 mm 5 mm 5 mm 10 mm 5 mm 5 mm 10 mm 5 mm 10 mm 10 mm test tube B test tube C discard Fig. 1.1

4 © UCLES 2011 0653/52/O/N/11 For Examiner's Use hydrochloric acid colourless agar block Fig. 1.2 Table 1.1 tube A B C cube dimensions / mm 10 x 10 x 10 10 x 10 x 5 10 x 5 x 5 volume of block / mm3 surface area of block / mm2 600 400 250 surface area to volume ratio / mm-1 time taken for block to go colourless / s (ii) Calculate the volume of each block. Record the volumes in Table 1.1. [1] (iii) The surface to volume ratio is calculated using the following formula: volume of block / mm3 surface area of block / mm2 ratio = Calculate the surface area to volume ratio for each block and record it in Table 1.1. [1]

5 © UCLES 2011 0653/52/O/N/11 [Turn over For Examiner's Use (iv) Explain why the blocks go colourless when placed in the acid. [2] (v) Describe and explain the effect that the decrease in volume of the block has on the time taken for the colour to change. [2] (b) Suggest one potential source of error in the experiment. [1]

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7 © UCLES 2011 0653/52/O/N/11 [Turn over For Examiner's Use 2 Carry out the following tests on solid X which is a mixture of two salts. Record your observations and conclusions in the appropriate boxes in Table 2.1. Table 2.1 test observation conclusion (a) Mix one spatula full of solid X with two spatulas full of calcium hydroxide in a hard glass test-tube. Heat gently. Test any gas with moist blue and red litmus papers. [1] [1] (b) Prepare about 20 cm3 of a dilute solution of X in water for use in the tests below. (i) To a portion of the solution of X, in a test-tube, slowly add aqueous sodium hydroxide until there is no further change. [1] [1] (ii) Acidify another portion of the solution of X with dilute nitric acid, then add barium nitrate solution. [1] [1] (iii) Acidify another portion of the solution of X with dilute nitric acid, then add silver nitrate solution. [1] [1] (c) Suggest names for the two salts in mixture X. and [2]

8 © UCLES 2011 0653/52/O/N/11 For Examiner's Use 3 (a) You are going to investigate how the displacement of light passing through a rectangular glass block depends on the angle of incidence. glass block paper Fig. 3.1 i incident ray normal not to scale 2 cm d continued incident ray emergent ray Fig. 3.2 • Place the glass block on the centre of the paper as shown in Fig. 3.1. Using a pencil, draw carefully around the block. • Remove the block and construct a normal, 2 cm from the end of one of the long sides as shown in Fig. 3.2. Using a protractor, draw and label lines to represent incident rays with angles of incidence i of 20°, 40°, 60° and 80°. • Replace the block carefully in the area marked on the paper. Place two pins about 4 cm apart on the incident ray for angle i =20°. • Look through the block from the other side and place two more pins (on the emergent ray) in line with the pins on the incident ray. • Remove the block and draw a line to represent the emergent ray. Then continue the incident ray as shown by the dotted line in Fig. 3.2. Now measure the displacement d of the incident ray as shown in Fig. 3.2. Record the value of d in mm in Table 3.1. • Repeat for the other angles of incidence i = 40°, 60°, and 80°.

9 © UCLES 2011 0653/52/O/N/11 [Turn over For Examiner's Use Table 3.1 angle of incidence i / ° displacement d / mm 0 0 20 40 60 80 [5] (b) (i) Plot a graph of displacement d (vertical axis) against angle of incidence i. You will need to extend the axes to include i = 90°. Draw the best curve through your points extending the curve to i = 90°. displacement, d / mm 0 20 40 60 80 10 30 50 70 90 0 angle of incidence, i / degrees [2]

10 © UCLES 2011 0653/52/O/N/11 For Examiner's Use (ii) Using your graph, find the value of the displacement, d90, when i = 90°. Show how you did this on the graph. d90 = mm [2] (c) Identify one source of error in your experiment. [1]

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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 2011 0653/52/O/N/11 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 2011 question paper for the guidance of teachers 0653 COMBINED SCIENCE 0653/52 Paper 5 (Practical), 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. • Cambridge will not enter into discussions or correspondence in connection with these mark schemes. Cambridge is publishing the mark schemes for the October/November 2011 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 2011 0653 52 © University of Cambridge International Examinations 2011 1 (a) (i) 1 reading of time in seconds only ; all 3 readings of time ; the 3 readings become shorter in time ; [3] (ii) 1000, 500, 250 ; [1] (iii) 0.6, 0.8, 1.0 OR 0.6:1, 0.8:1, 1.0:1 ; [1] (iv) diffusion ; (acid) neutralising (the alkali) ; [2] (v) time decreases with decrease in volume / rate increases with decrease in volume OR reverse argument ; due to larger surface area : volume ratio ; faster diffusion ; shorter diffusion distance ; [max 2] (b) judgment of end point ; inaccuracy of cutting ; temperature not controlled ; soft agar splitting and so increasing surface area ; [max 1] [Total: 10] 2 (a) observation: (red) litmus goes blue ; [1] conclusion: ammonia gas / alkaline gas / NH3 / ammonium / NH4 + (tied to observation) ; [1] (b) (i) observation: white ppt. / ppt. dissolves in excess ; [1] conclusion: zinc / Zn2+ (tied to white ppt.) do not allow Zn only ; [1] (ii) observation: white ppt. ; [1] conclusion: sulfate / SO4 2– (tied to observation) ; [1] (iii) observation: white ppt. ; [1] conclusion: chloride / Cl – (tied to observation) ; [1] (c) zinc chloride / ZnCl2 ; ammonium sulfate / (NH4)2SO4 ; OR zinc sulfate / ZnSO4 ; ammonium chloride / NH4Cl ; [max 2] (allow a correct cation AND correct anion for 1 mark e.g. zinc / Zn2+ and chloride / Cl –) [Total: 10]

Page 3 Mark Scheme: Teachers’ version Syllabus Paper IGCSE – October/November 2011 0653 52 © University of Cambridge International Examinations 2011 3 (a) d in mm ; d for 20° ; d for 20° and one other angle ; all readings of d ; d increasing as i increases (allow only if 4 or 5 readings) ; [5] (b) (i) 4 points plotted to within ½ a square ; appropriate curve (probably curve at start and straight line at higher values of i) ; (allow double curve if spread of points is great enough) [2] (iii) appropriate extrapolation (do not allow extrapolation of a straight line or zig zag line) ; correct reading of d90 from attempted extrapolation of graph (allow reading of an extrapolation off the grid if done accurately) ; [2] (c) visual lining up of pins (not parallax error) ; error in extrapolation of graph ; placing block accurately within lines on paper ; 80° hard to see / owtte ; [max 1] [Total: 10]