Cambridge IGCSE Science - Combined 0653 — 2014 Oct/Nov Paper 5 · Variant 1

This document consists of 9 printed pages and 3 blank pages. IB14 11_0653_51/2RP © UCLES 2014 [Turn over *0109370997* For Examiner's Use 1 2 3 Total Cambridge International Examinations Cambridge International General Certificate of Secondary Education COMBINED SCIENCE 0653/51 Paper 5 Practical Test October/November 2014 1 hour 30 minutes 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.

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3 © UCLES 2014 0653/51/O/N/14 [Turn over 1 You are going to investigate the relationship between yeast activity and temperature. You are provided with 50 cm3 yeast and sugar suspension. You are also provided with two large beakers, ice and a supply of hot and cold water. • Label one beaker A and the other B. • Using a thermometer and the materials provided, create and maintain two water baths. The depth of water in each beaker should be about one third of the depth of the beaker. Beaker A should be maintained in the range 15 – 20 °C and beaker B in the range 35 – 40 °C. A syringe or dropping pipette is provided to help with the removal or addition of water. • Stir the yeast suspension and immediately measure out 20 cm3 into each of two large test-tubes. • Place one of the test-tubes containing the yeast suspension into beaker A and the other into beaker B. • The water in the beaker should be at about the same height as the yeast and sugar suspension in the test-tube, as shown in Fig. 1.1. water test-tube beaker Fig. 1.1 (a) Measure and record, to the nearest °C, the temperature of the water in each beaker. beaker A °C beaker B °C [1]

4 © UCLES 2014 0653/51/O/N/14 (b) Use a ruler to measure the height h of the liquid (including any foam) in the test-tubes of beaker A and beaker B as shown in Fig. 1.2. Record your measurements in Table 1.1 for time = 0 minutes. h Fig. 1.2 • Start the stopclock. • Every two minutes for the next ten minutes, measure and record the height h (including any foam) in each test-tube. During this time, maintain the temperatures of the beakers within the given ranges. • Record your measurements in Table 1.1. [3] Table 1.1 time / minutes height h in beaker A / mm height h in beaker B / mm 0 2 4 6 8 10

5 © UCLES 2014 0653/51/O/N/14 [Turn over (c) On the grid provided, plot graphs of height h against time for each beaker. Draw best fit lines and label them A for beaker A and B for beaker B. 0 1 2 3 4 5 6 7 8 9 10 time / minutes [4] (d) By using your knowledge of respiration, name the gas which is produced to make the foam. gas [1] (e) By referring to your results in Table 1.1 and the graph, suggest a relationship between yeast activity and temperature. [1]

6 © UCLES 2014 0653/51/O/N/14 2 Solid Q is a mixture of three compounds. You will separate the compounds and carry out tests to identify two of the cations contained in solid Q. (a) Place the sample of solid Q in a small beaker and add about 25 cm3 distilled water. Stir well for at least one minute, then filter the mixture into a large test-tube. Keep the filtrate and residue for further testing in (b) and (c). Record the colours of the filtrate and residue. colour of filtrate colour of residue [2] (b) (i) Place about 2 cm3 of the filtrate from (a) into a test-tube and slowly add dilute sodium hydroxide until the test-tube is almost full. Now carefully stir the mixture in the test-tube. Record your observations. [1] (ii) Place about 2 cm3 of the filtrate from (a) into another test-tube and slowly add ammonia solution until the test-tube is almost full. Now carefully stir the mixture in the test-tube. Record your observations. [1] (iii) Use your observations in (b)(i) and (b)(ii) to identify the cation present in the filtrate from (a). identity of cation [1]

7 © UCLES 2014 0653/51/O/N/14 [Turn over (c) (i) Place the residue and filter paper from (a) into a clean small beaker and add 25 cm3 dilute hydrochloric acid. Stir carefully. Gently warm the beaker on a tripod and gauze for two minutes. Do not boil the liquid in the beaker. Remove the source of heat. Record your observations and keep the mixture for (c)(ii). [1] (ii) When the mixture from (c)(i) has cooled a little, filter it into a large test-tube. Keep the filtrate for further testing in (d). Record the colours of the filtrate and residue. colour of filtrate colour of residue [2] (d) Place about 2 cm3 of the filtrate from (c)(ii) into a test-tube and slowly add dilute sodium hydroxide until the test-tube is almost full. Now carefully stir the mixture in the test-tube. Record your observations and identify the cation present. observations identity of cation [2]

8 © UCLES 2014 0653/51/O/N/14 3 You are going to find out how the resistance of a wire depends upon its length. The circuit shown in Fig. 3.1 has been set up for you. A V l power source switch X Y sliding contact C resistance wire metre rule Fig. 3.1 (a) (i) Close the switch and place the sliding contact C on the resistance wire at a distance l of 10.0 cm from end X. Record the current I flowing through the wire and the potential difference (p.d.)V across the wire in Table 3.1. Record also the length l. Switch off. [1] Table 3.1 length l / cm current I / A p.d. V / V resistance R / ohms (ii) Calculate the resistance R of the 10.0 cm length of the wire using the equation. R = V / I Record the value of R in the table. [1] (iii) Repeat steps (i) and (ii) for values of l of 40.0 cm, 70.0 cm and 85.0 cm, switching off after each measurement. Record your values of l, I, V and R in Table 3.1. [3]

9 © UCLES 2014 0653/51/O/N/14 [Turn over (iv) Suggest why it is important to switch the circuit off between taking readings. [1] (b) On the grid provided, plot a graph of R (vertical axis) against l (horizontal axis). Start your graph at (0,0). Draw the best fit straight line. R / Ω l / cm [3] (c) Use your graph to suggest the relationship between the resistance R of the wire and its length l. relationship [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. 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 2014 0653/51/O/N/14 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 October/November 2014 series 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 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 October/November 2014 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 – October/November 2014 0653 51 © Cambridge International Examinations 2014 1 (a) both temperatures recorded to nearest °C and within range for each water-bath ; [1] (b) at least 4 pairs of results recorded ; (do not allow h = 0) all pairs of results recorded in mm and not greater than 200 ; height generally higher in B than A ; [3] (c) linear vertical axis labelled with height and units ; at least 5 correct plots to ± ½ small square for B (for A if B not plotted) ; points plotted for A and B and both labelled ; best fit curve or straight lines for A and B ; [4] (d) carbon dioxide ; [1] (e) higher yeast activity with higher temperature / it increases with temperature / it is faster at higher temperature ; (mark may only be awarded if there are results in the table) [1] [Total: 10] 2 (a) filtrate: colourless ; residue: brown / black / grey ; (colours reversed 1 mark max) [2] (b) (i) white ppt. / ppt. disappears to form colourless solution / ppt. soluble in excess (NaOH) ; [1] (ii) white ppt. / ppt. disappears to form colourless solution / ppt. soluble in excess (ammonia solution) ; [1] (iii) Zn2+ / zinc ; (not Zn) (mark is linked to a correct observation in (b)(i) or (b)(ii)) [1] (c) (i) bubbles / effervescence (ignore colours) ; [1] (ii) filtrate: green / turquoise / blue ; residue: brown / black / grey ; (colours reversed 1 mark max) [2] (d) observation: (pale) blue ppt. ; Cu2+ / copper ; (not Cu) (independent mark) [2] [Total: 10]

Page 3 Mark Scheme Syllabus Paper Cambridge IGCSE – October/November 2014 0653 51 © Cambridge International Examinations 2014 3 (a) (i) all three values present with l =10 cm and I less than 1 ; [1] (ii) R value correct for l =10 cm and minimum of two significant figures ; [1] (iii) V values increasing (for increasing length) ; R values correct for l = 40 cm onwards ; consistent two to three significant figures for R ; [3] (iv) so that the wire does not become hot / because resistance of wire may increase / as battery or cell may run down ; [1] (b) suitable choice of linear scales and use of at least 50% of each axis ; (no marks may be awarded in (b) for a non-linear scale) at least three plots correct to ± ½ small square; good best fit straight line judgement ; [3] (c) proportional ; [1] [Total: 10]