Cambridge IGCSE Sciences - Co-ordinated (Double) 0654 — 2010 Oct/Nov Paper 5 · Variant 2

This document consists of 10 printed pages and 2 blank pages. IB10 11_0654_52/5RP © UCLES 2010 [Turn over *6175511817* For Examiner's Use 1 2 3 Total UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS International General Certificate of Secondary Education CO-ORDINATED SCIENCES 0654/52 Paper 5 Practical Test October/November 2010 2 hours 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 2010 0654/52/O/N/10 For Examiner's Use 1 (a) (i) Some fruit juices contain protease enzymes. You will be investigating fruit juices to find if they digest proteins. You will find out if a sample of protein loses mass after immersion in the juice. • Label four pieces of paper towel 1, 2, 3 and 4. • Put four large test-tubes into a test-tube rack or beaker. Label them 1, 2, 3 and 4. • Divide the solid protein into four pieces, each about the same size. • Weigh the first piece of protein and record the mass in Table 1.1. • Cut this piece of protein into approximately 10 pieces. Put the pieces into the tube 1. • Treat the remaining three pieces of protein in the same way for tubes 2, 3 and 4. Table 1.1 test-tube number 1 2 3 4 mass of protein / g type of juice • Measure 20 cm3 of juice 1 and add this to tube 1. Record the type of fruit juice in Table 1.1. • Add 20 cm3 of juice 2 to tube 2, recording the type of fruit juice in Table 1.1. • Repeat this with the remaining two fruit juices, juice 3 and juice 4. [2] (ii) Using the hot water provided make a water bath with a temperature of 50 ºC in a large beaker. Stand all four tubes in this for 10 minutes. Monitor the temperature during this time. If the temperature falls below 40 ºC add more hot water to keep the temperature between 40 ºC and 50 ºC. During this time create a table for the results of the four tubes. This should include the type of juice, the mass of protein at the start, the mass of protein at the end, and the change in mass. [2]

3 © UCLES 2010 0654/52/O/N/10 [Turn over For Examiner's Use (b) After 10 minutes do the following. • Carefully pour off and discard the fruit juice from tube 1 into a beaker. Place all the pieces of protein on towel no. 1 and blot the protein dry. • Weigh all the pieces of protein together and record the mass in the table you have made. • Repeat this with the protein in tubes 2, 3 and 4. Calculate the change in mass for the protein from each tube and enter in your table. [4] (c) Which fruit juice showed the greatest protease activity? Explain your answer. fruit juice explanation [2] (d) Suggest a suitable control for the experiment and explain your answer. control explanation [2] (e) At least one of the juices you were given is known to be acidic. Design an experiment to find if the loss in mass could have been due to acid present in the fruit juice rather than the protease. [3]

4 © UCLES 2010 0654/52/O/N/10 For Examiner's Use 2 You are going to measure the refractive index of a semi-circular block by two different methods. (a) (i) Place the semi-circular block on the grid, Fig. 2.3, with its curved edge downwards as shown in Fig. 2.1. glass block grid Fig. 2.1 Look through the flat side of the block at the grid (see Fig. 2.2). Place a ruler alongside the top edge of the grid and measure the length of the clear image of the grid, d1, that you can see in the block. Do not count the number of grid marks. d1 d2 grid glass block Fig. 2.2 Fig. 2.3 Record the length d1. d1 = mm [1]

5 © UCLES 2010 0654/52/O/N/10 [Turn over For Examiner's Use (ii) Measure and record the length of the flat side of the block which you have looked through, d2, as shown in Fig. 2.2. d2 = mm [1] (iii) Calculate the value of 1 2 d d . This is the refractive index of the block. [1] 1 2 d d = (b) (i) Now place the semi-circular block on a piece of plain paper and draw round it. Remove the block; mark the centre point of the flat side. Draw a normal at this point and construct incident rays with incident angles, i, of 0°, 10°, 20°, 30° and 40° as shown in Fig. 2.4. normal refracted ray 0 10 20 30 40 10° i r ° incident rays Fig. 2.4 • Replace the block on the paper. • Place 2 pins about 4 cm apart on the incident ray you have drawn with an angle, i = 10°. • Look through the block from the other side and place 2 more pins (on the refracted ray) in line with the pins on the incident ray. • Remove the block, draw the refracted ray and measure the angle of refraction, r°. Record the value of r° in Table 2.1. • Repeat the procedure with the other incident rays to find the other angles of refraction.

6 © UCLES 2010 0654/52/O/N/10 For Examiner's Use Table 2.1 i° sine i r° sine r 0 0.00 0 0.00 10 0.17 20 0.34 30 0.50 40 0.64 [4] (ii) Using the Table 2.2 below, or using a calculator, find the sine value for each angle of refraction, r°, and record each sine r value next to its angle in Table 2.1. The sine values for the angles of incidence, i, have been entered in the table for you already. Table 2.2 angle / ° sine angle / ° sine angle / ° sine 0 0.00 30 0.50 49 0.75 10 0.17 31 0.52 50 0.77 11 0.19 32 0.53 51 0.78 12 0.21 33 0.54 52 0.79 13 0.22 34 0.56 14 0.24 35 0.57 70 0.94 15 0.26 36 0.59 71 0.95 16 0.28 40 0.64 72 0.95 17 0.29 45 0.71 73 0.96 18 0.31 46 0.72 74 0.96 19 0.33 47 0.73 75 0.97 20 0.34 48 0.74 76 0.97 [1]

7 © UCLES 2010 0654/52/O/N/10 [Turn over For Examiner's Use (c) (i) Plot a graph on the grid below of sine r (vertical axis) against sine i (horizontal axis) using the values in Table 2.1. Draw the best straight line through the points. [4] (ii) Determine the gradient of the line showing your working. This is equal to the refractive index of the block. gradient = [2] (iii) Suggest why the value of the refractive index found using the gradient of the graph will be more accurate than your result from (a)(iii). [1]

8 © UCLES 2010 0654/52/O/N/10 For Examiner's Use 3 You are provided with four solutions labelled A, B, C and D. The four solutions are: hydrochloric acid, HCl nitric acid, HNO3 potassium nitrate, KNO3 sodium chloride, NaCl You will carry out two tests on each solution to find out which is which. (a) Test 1 • To about 1 cm3 of solution A in a test-tube add a spatula full of sodium carbonate solid, Na2CO3. Record your observations in Table 3.1. • Repeat the test using solutions B, C and D, using a fresh test-tube for each solution. • Complete Table 3.1 to show your conclusion for each test and the two possible identities for each solution. Table 3.1 solution observations on adding sodium carbonate conclusion of test possible identities of the solution or A or B or C or D [6]

9 © UCLES 2010 0654/52/O/N/10 [Turn over For Examiner's Use (b) Test 2 • To about 1 cm3 of a fresh sample of solution A add an equal volume of silver nitrate solution, AgNO3. Record your observations in Table 3.2. • Repeat the test using solutions B, C and D, using a fresh test-tube for each solution. • Complete Table 3.2 to show your conclusion for each experiment and the identity of each solution. • To establish the identity of each solution you will have to consider the results and conclusions of tests 1 and 2. Table 3.2 solution observations on adding silver nitrate solution conclusion of test identity of the solution A B C D [6] (c) Describe how you would show the presence of the nitrate ion in a sample of potassium nitrate solution. You do not need to carry out this experiment. [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 0654/52/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 0654 CO-ORDINATED SCIENCE 0654/52 Paper 5 (Practical), maximum raw mark 45 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 0654 52 © UCLES 2010 1 (a) (i) masses recorded correctly ; (5–15 g to at least 1 decimal point) name of juice recorded correctly ; [2] (ii) table headings correct including units (at least once) ; table laid out correctly ; [2] (b) calculation correct for tube 1 ; calculation correct for tube 2 ; calculation correct for tube 3 ; calculation correct for tube 4 ; (if there is increase, not greater than 10 %) [4] (c) correct answer from student’s data ; shows greatest loss in mass, or greatest proportional loss ; [2] (d) use water instead of juice ; see if the protein would have lost mass anyway ; [2] (e) set up same experiment with protein and acid ; weigh protein before and after experiment ; compare masses to see if any mass lost ; [3] alternative answer: neutralise acid in juice ; weigh protein before and after ; if mass still lost, then its protease and not acid ; [Total: 15]

Page 3 Mark Scheme: Teachers’ version Syllabus Paper IGCSE – October/November 2010 0654 52 © UCLES 2010 2 (a) (i) value of d1 must be less than d2 but greater than d2 / 2 ; (if clearly in cm do not give mark) [1] (ii) value of d2 (should be close to supervisor value if no note about size of blocks differing) ; [1] (iii) correct calculation of d2 / d1 ((at least 1 decimal point recorded), any rounding up must be correct) ; [1] (b) (i) i ° sine i r ° sine r 0 0.00 0 0.17 20 0.34 30 0.50 40 0.64 ; all other r values greater than matching i value ; r value increase with increasing i ; 4 readings of r ; [4] (ii) correct sine r values put in table ; [1] (c) (i) axes must be labelled with sine r vertical and sine i horizontal ; scales must be marked clearly and must be linear ; (0,0) plotted or line through zero at least 3 points must be plotted within ½ square ; best straight line through points ; [4] (ii) correct value of gradient ignoring decimal places but not allowing incorrect rounding ; working can be fraction or triangle on graph with figures on sides of triangle ; [2] (iii) it is the average of several readings / idea of more than one set of readings ; or looking through block is difficult to do ; [max 1] [Total: 15]

Page 4 Mark Scheme: Teachers’ version Syllabus Paper IGCSE – October/November 2010 0654 52 © UCLES 2010 3 (a) solution observation on adding sodium carbonate conclusion the solution must have the following present possible identities of solution A fizzes / bubbles / effervesces acid / H+ HCl HNO3 B no reaction / solid dissolves no acid / no H+ NaCl KNO3 C no reaction / solid dissolves no acid / no H+ NaCl KNO3 D fizzes / bubbles / effervesces acid / H+ HCl HNO3 whole observation column correct ; whole conclusion column correct ; the two possible identities for each solution ;;;; [6] (b) solution observation on adding silver nitrate solution conclusion the solution must have the following present identity of solution A white ppt / white solid chloride / Cl – HCl / hydrochloric acid B white ppt / white solid chloride / Cl – NaCl / sodium chloride C no reaction / remains colourless no chloride / no Cl KNO3 / potassium nitrate D no reaction / remains colourless no chloride / no Cl HNO3 / nitric acid whole observation column correct ; whole conclusion column correct ; the correct identity for each solution ;;;; [6] (c) add aqueous sodium hydroxide / NaOH, plus aluminium / Al, plus warm / heat ; damp red litmus (paper) in gas / mouth of test tube ; litmus turns blue (if states ammonia given off without test, allow 1 mark) ; [3] [Total: 15]