Cambridge IGCSE Sciences - Co-ordinated (Double) 0654 — 2015 May/June Paper 5 · Variant 2

This document consists of 11 printed pages and 1 blank page. IB15 06_0654_52/3RP © UCLES 2015 [Turn over *0338635416* For Examiner's Use 1 2 3 Total Cambridge International Examinations Cambridge International General Certificate of Secondary Education CO-ORDINATED SCIENCES 0654/52 Paper 5 Practical Test May/June 2015 2 hours Candidates answer on the Question Paper. Additional Materials: As listed in the Confidential Instructions. 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 an HB pencil for any diagrams or graphs. Do not use staples, paper clips, glue or correction fluid. DO NOT WRITE IN ANY BARCODES. Answer all questions. Electronic calculators may be used. You may lose marks if you do not show your working or if you do not use appropriate units. Notes for Use in Qualitative Analysis 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.

2 © UCLES 2015 0654/52/M/J/15 1 Catalase is an enzyme found in potato cells. It is involved in the breakdown of hydrogen peroxide into water and oxygen. The oxygen is released as oxygen bubbles. You are going to investigate how the rate of this reaction is affected by the thickness of potato pieces. (a) Read through the instructions for the whole of part (a) carefully before starting. (i) Complete Table 1.1 by adding appropriate headings to column one and columns two to four, including units. [1] Table 1.1 / / experiment 1 experiment 2 average 5 4 3 2 1 (ii) • Take one of the potato cylinders and remove any skin by trimming off about 1 cm from the end and discard this piece into the waste container. • Using the ruler and knife, cut a 5 mm thick slice from the freshly cut end. • Using forceps, pick up this slice and place it at the bottom of the beaker containing hydrogen peroxide. At the same time that the potato enters the hydrogen peroxide, start the stopclock. • The slice of potato will begin to rise to the surface as it gets covered with bubbles. When it reaches the surface, stop the stopclock. • Using forceps, immediately remove and discard this potato slice. Record in Table 1.1 the time it takes, to the nearest second, for the slice to rise to the surface of the hydrogen peroxide (experiment 1). • Repeat the procedure with potato slices of thicknesses of 4 mm, 3 mm, 2 mm and 1 mm. Record these times in Table 1.1 (experiment 1). [2] (iii) Using the same hydrogen peroxide, repeat the procedures in (a)(ii), cutting fresh potato slices from the other potato cylinder. Record your results in Table 1.1 (experiment 2). [2] (b) Calculate the average time for each thickness of potato slice and complete Table 1.1. [1]

3 © UCLES 2015 0654/52/M/J/15 [Turn over (c) On the grid provided plot a graph of the average time taken on the vertical axis, against slice size on the horizontal axis. Draw a best fit straight line through the origin. [4] (d) Use your graph to estimate the time that a 2.5 mm slice would take to rise to the surface. Draw lines on your graph to show how you worked this out. time taken = s [1]

4 © UCLES 2015 0654/52/M/J/15 (e) Using your knowledge of enzymes, predict what would happen to the number of bubbles if (i) the experiment was carried out at 5 °C, [1] (ii) boiled potato was used for this experiment. [1] (f) A student suggests that in experiment 2 in part (a) fresh hydrogen peroxide should be used. (i) Explain why this would make the experiment a fairer test. [1] (ii) Compare your results in Table 1.1 for experiment 1 and experiment 2 to explain whether using fresh hydrogen peroxide would make a difference. [1]

5 © UCLES 2015 0654/52/M/J/15 [Turn over Please turn over for Question 2.

6 © UCLES 2015 0654/52/M/J/15 2 You are provided with samples of four compounds as solids A, B, C and D. One of the solids is sodium carbonate and another is sodium chloride. You will carry out tests to find the identities of A, B, C and D. For this purpose you are provided with the following reagents: • ammonia solution • barium chloride solution • dilute hydrochloric acid • limewater • silver nitrate solution (a) Find out which solid contains carbonate. Test no more than half of each solid. Use a test that does not involve heat. (i) Describe the test that you use, which must include the test for any gas produced. You may draw a labelled diagram of the apparatus as a description. test [3] (ii) Record your observations in Table 2.1 and indicate which compound is the carbonate. Table 2.1 solid A solid B solid C solid D observations carbonate present? (yes/no) [3]

7 © UCLES 2015 0654/52/M/J/15 [Turn over (b) Now put to one side the solid you have identified as a carbonate. You will not need this again. You will now test the three remaining samples. (i) Dissolve one small spatula load of one of the remaining solids in a large test-tube containing one third distilled water. You may need to stir the mixture. Divide this solution equally into three test-tubes. Place the test-tubes into the test-tube rack. Carry out the following tests: • Add barium chloride solution to one test-tube. • Add silver nitrate solution to the second test-tube. • Add ammonia solution to the third test-tube. Record your observations in the first empty column of Table 2.2. Complete the ‘solid...’ heading. (ii) Repeat (i) using the second remaining solid. (iii) Repeat (i) using the third remaining solid. Table 2.2 test (b)(i) (b)(ii) (b)(iii) solid solid solid barium chloride solution silver nitrate solution ammonia solution [6] (c) (i) State which solid is sodium chloride. sodium chloride is solid [1] (ii) You have now identified sodium carbonate and sodium chloride. Using your observations in (b), name the other two solids. [2]

8 © UCLES 2015 0654/52/M/J/15 3 You are going to measure the focal length of a convex lens. Set up the apparatus as shown in Fig. 3.1. The distance between the front of the lamp and the illuminated object should be 2 to 3 cm. triangular illuminated object u v screen H bench Fig. 3.1 (a) Measure and record in millimetres to the nearest millimetre, the height H of your triangular illuminated object. Fig. 3.2 shows where you should measure H. H = mm [1] H Fig. 3.2 (b) (i) Switch on the lamp and place the lens at a distance u = 25.0 cm from the illuminated object. Adjust the position of the screen by moving it backwards and forwards along the bench until a sharp triangular image of the illuminated object is formed on the screen. Measure, as accurately as you can, the image distance v from the screen to the lens. Record the distance v in Table 3.1. [1] (ii) Measure, and record in millimetres in Table 3.1, the height h of this image on the screen. [1] Table 3.1 u / cm v / cm h / mm m = H h 25.0 30.0 35.0 40.0 45.0

9 © UCLES 2015 0654/52/M/J/15 [Turn over (iii) Repeat the procedure described in (b)(i) and (b)(ii) for values of u of 30.0 cm, 35.0 cm, 40.0 cm and 45.0 cm. [2] (iv) Use your result from (a) and the values of h in the table to complete the final column in Table 3.1 by calculating each ratio H h . This ratio is called the magnification m of the image. [1] (c) (i) On the grid provided, plot a graph of m against v. Draw the best fit straight line. The horizontal and vertical axes do not need to start from zero. m v / cm [3]

10 © UCLES 2015 0654/52/M/J/15 (ii) Calculate the gradient of your line. Show all working and indicate on your graph the values you chose to enable an accurate value of the gradient to be calculated. gradient = [2] (iii) Calculate the focal length of the lens using the equation f = gradient 1 . f = cm [2] (d) State two precautions that you should take in this experiment to obtain accurate results. precaution 1 precaution 2 [2]

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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. To avoid the issue of disclosure of answer-related information to candidates, all copyright acknowledgements are reproduced online in the Cambridge International Examinations Copyright Acknowledgements Booklet. This is produced for each series of examinations and is freely available to download at www.cie.org.uk after the live examination series. 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 2015 0654/52/M/J/15 NOTES FOR USE IN QUALITATIVE ANALYSIS 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

® IGCSE is the registered trademark of Cambridge International Examinations. CAMBRIDGE INTERNATIONAL EXAMINATIONS Cambridge International General Certificate of Secondary Education MARK SCHEME for the May/June 2015 series 0654 CO-ORDINATED SCIENCES 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 should be read in conjunction with the question paper and the Principal Examiner Report for Teachers. Cambridge will not enter into discussions about these mark schemes. Cambridge is publishing the mark schemes for the May/June 2015 series for most Cambridge IGCSE®, Cambridge International A and AS Level components and some Cambridge O Level components.

Page 2 Mark Scheme Syllabus Paper Cambridge IGCSE – May/June 2015 0654 52 © Cambridge International Examinations 2015 1 (a) (i) ‘thickness or size / mm’ and ‘time taken / s or seconds’ ; [1] (ii) full set of results recorded for experiment 1 ; all to the nearest second ; [2] (iii) full set of results recorded for experiment 2 ; correct trend in both experiments (time taken decreases down column) ; [2] (ALLOW trend mark if only 4 results in column or if 5 results with two consecutive ones the same) (b) averages calculated correctly ; [1] (c) labelled axes with units ; suitable choice of scale using at least half of each axis (IGNORE (0,0)) ; at least 4 points plotted correctly ± half small square ; best-fit straight line through the origin (± half small square) ; [4] (d) at least one line on graph and correct reading from graph ; [1] (e) (i) fewer bubbles (comparison required) [1] (ii) no bubbles / very few bubbles ; [1] (f) (i) same concentration of hydrogen peroxide each time / hydrogen peroxide used up in experiment 1 ; [1] (ii) experiment 2 has similar results so not necessary / experiment 2 has greater times so it is necessary / experiment 2 greater time but similar trend so not necessary ; [1] (Answer should match candidate’s results)

Page 3 Mark Scheme Syllabus Paper Cambridge IGCSE – May/June 2015 0654 52 © Cambridge International Examinations 2015 2 (a) (i) (test) add dilute hydrochloric acid (to solid) ; 2 test-tubes (or suitable containers) connected via delivery tube ; bubble any gas through limewater ; (marks could be obtained from fully labelled correct diagram) [3] (ii) Table 2.1 A B C D observations no change (limewater) white ppt. / milky / cloudy white no change no change carbonate present? (yes / no) no yes no no (limewater) white ppt. / milky / cloudy white for B ; no change for A, C and D ; carbonate present row all correct (allow ecf from incorrect results) ; (note: all results present but interchange of letters = max 2) [3] (b) Table 2.2 Note: (i), (ii) and (iii) will not necessarily be in order A, C and D. (i) (ii) (iii) test A C D barium chloride solution no reaction white ppt. white ppt. (allow pale blue ppt.) silver nitrate solution white ppt. no or slight ppt. no or slight ppt. ammonia solution no reaction white ppt. (dissolves to form colourless solution) blue ppt. dissolves to form dark blue solution ALLOW nothing / – / no visible reaction for no ppt. (i) (for A) white ppt. with silver nitrate and nothing with others ; [1] (ii) (for C) white ppt. with barium chloride ; white ppt. with ammonia solution (note: do not award this mark if white ppt. with silver nitrate although allow slight ppt. with silver nitrate) [2]

Page 4 Mark Scheme Syllabus Paper Cambridge IGCSE – May/June 2015 0654 52 © Cambridge International Examinations 2015 (iii) (for D) white ppt. with barium chloride ; blue ppt. with ammonia solution (note: do not award this mark if white ppt. with silver nitrate although allow slight ppt. with silver nitrate) ; dark blue solution with ammonia ; [3] [note: If B appears in Table 2.2 then mark B results as follows depending on which substance B has replaced B instead of A: white ppt. with barium chloride ; B instead of C: white ppt. with barium chloride ; brown ppt. with silver nitrate ; B instead of D: white ppt. with barium chloride ; brown ppt. with silver nitrate ; nothing with ammonia ; ] (c) (i) A ; [1] (note: A must be present and correct in Table 2.2) (ii) zinc sulfate ; (note: C must be present and correct in Table 2.2) copper sulfate ; [2] (note: D must be present and correct in Table 2.2)

Page 5 Mark Scheme Syllabus Paper Cambridge IGCSE – May/June 2015 0654 52 © Cambridge International Examinations 2015 3 (a) H recorded to the nearest millimetre (15–19 or SV±2) ; [1] (b) (i) value of v recorded for u = 25 ; [1] (ii) value of h recorded for u = 25 ; [1] (iii) table complete for v and h ; [2] values of v decreasing down table ; (iv) all ratios calculated correctly to at least 2 sig. fig. ; [1] (c) (i) suitable choice of scales using at least half of each axis ; at least 4 points plotted correctly ± half small square ; good best-fit straight line judgment ; [3] (ii) indication on graph of how data obtained AND use of at least half of line drawn ; correct calculation to at least 2 sig fig using data from the graph ; [2] (iii) focal length correctly calculated to 2 / 3 sig. fig. from candidate’s gradient value ; focal length = 14–16 cm (adjust to SV±1 as necessary) ; [2] (d) any two from: use of darkened room / use a brighter lamp ; mark position of centre of lens in holder ; place metre rule on bench / clamp in position ; ensure the centre of lens and object are the same height above bench / object and screen vertical ; repeat and average ; (DO NOT ALLOW place zero of ruler on illuminated object) [max 2]