Cambridge IGCSE Science - Combined 0653 — 2011 Oct/Nov Paper 5 · Variant 1

This document consists of 9 printed pages and 3 blank pages. IB11 11_0653_51/4RP © UCLES 2011 [Turn over *5597758989* 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 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 0653/51/O/N/11 For Examiner's Use 1 (a) You are going to compare the activity of the enzyme catalase in raw and boiled yeast. Catalase accelerates the decomposition of hydrogen peroxide and is found in most living cells. • Label 5 large test-tubes A, B, C, D, and E. Use the permanent marker to draw a line on each tube 1 cm below the top. • Place the large test-tubes into a rack and measure out 20 cm3 of hydrogen peroxide solution into each tube. (i) ● Place a few drops of the fresh yeast suspension into the hydrogen peroxide in test-tube A. • Place a glowing splint into test-tube A, just above the hydrogen peroxide and yeast mixture. • Record your observation and state the name of the gas that has been produced. observation name of gas produced [2] (ii) ● Add two drops of detergent to the hydrogen peroxide in test-tubes B, C and D. • Measure out 5 cm3 of fresh yeast suspension into a syringe or dropping pipette. Place the yeast into the hydrogen peroxide in test-tube B. • Start the stop-clock as soon as the yeast makes contact with the hydrogen peroxide. • In Table 1.1, record the time taken in seconds for the foam to reach the pen line. • Repeat for tubes C and D. [2] Table 1.1 yeast type fresh boiled tube B C D E time taken / s (iii) Calculate the average time, in seconds, for the fresh yeast (tubes B, C and D). [1]

3 © UCLES 2011 0653/51/O/N/11 [Turn over For Examiner's Use (b) (i) ● Measure out 5 cm3 of boiled yeast into a syringe or dropping pipette. • Place the yeast suspension into the hydrogen peroxide in large test-tube E. • Start the stop-clock and record, in Table 1.1, the time taken, in seconds, for the foam (if any) to reach the pen line on the test-tube. • If no foam is produced, or the foam has not reached the line after two minutes, record ‘No reaction’ in Table 1.1. [1] (ii) Compare the results for the fresh and boiled yeast. Explain the difference in the activity of the enzyme catalase in the fresh and boiled yeast. [2] (c) (i) Are the results for tubes B, C and D reliable? Explain your answer. [1] (ii) Suggest one possible source of error in this experiment. [1]

4 © UCLES 2011 0653/51/O/N/11 For Examiner's Use 2 You are going to investigate the thermal decomposition of three metal carbonates and identify an unknown metal. (a) (i) Place compound A, which is a metal carbonate, in a clean hard glass test-tube. Place about 3 cm3 of limewater in a second test-tube. Connect the bung of the delivery tube to the test-tube containing A and place the delivery tube into the limewater as shown in Fig. 2.1. limewater metal carbonate A heat Fig. 2.1 (ii) Heat the tube containing compound A with a hot flame, starting the clock as you do so. When the limewater becomes milky, stop the clock and immediately remove the delivery tube from the limewater. Record the time taken, in seconds, for the limewater to become milky, as well as any colour change to the carbonate, in Table 2.1. Table 2.1 compound name and formula time / s colour change A zinc carbonate, ZnCO3 B magnesium carbonate, MgCO3 C unknown metal carbonate, XCO3 [1] (iii) Repeat (a)(i) and (a)(ii) with the compounds B and C, using fresh limewater each time. Record the results in Table 2.1. [2] Keep the test-tube containing the result of heating compound C for part (b).

5 © UCLES 2011 0653/51/O/N/11 [Turn over For Examiner's Use (iv) List the metal carbonates in order of their speed of turning limewater milky (speed of thermal decomposition). 1 (fastest) 2 3 (slowest) [1] (v) Name the gas produced by the thermal decomposition of a metal carbonate. name [1] (b) Empty the contents of the test-tube in which compound C was heated into a beaker. Add about 10 cm3 of dilute sulfuric acid and stir well. Filter the resulting mixture into two clean test-tubes. Keep the filtrate for parts (b)(i) and (b)(ii). (i) Carefully add dilute sodium hydroxide to the filtrate in one of the test-tubes until there is no further change. Record your observation. [1] (ii) To the other test-tube containing the filtrate, add a piece of zinc. Record your observations. [2] (iii) Identify metal X and state two pieces of evidence to support this. metal X is evidence 1 evidence 2 [2]

6 © UCLES 2011 0653/51/O/N/11 For Examiner's Use 3 You are going to investigate how the angle of swing, θ, affects the time period for one oscillation, T, of a simple pendulum. You will also use your results to calculate the acceleration due to gravity, g. (a) Set up your pendulum as in Fig. 3.1, using the apparatus provided, such that the length, l, is 30 cm. Clamp the cork and secure the protractor card to the cork with the short pin. Attach the protractor to the card as shown, using the long pin. Suspend the pendulum from the long pin. short pin long pin protractor card stand pendulum length, l Fig. 3.1 Displace the pendulum by θ = 10° as shown in Fig. 3.2. 0 180 170 160 150 140 130 120 110 100 80 70 60 50 40 30 20 10 0 10 20 30 40 50 60 70 80 100 110 120 130 140 150 160 170 180 90 θ Fig. 3.2 (i) Release the pendulum and start the clock at the same time. Stop the clock when the pendulum has completed ten oscillations. (One oscillation is swinging away from and back to the release point). Record the time in Table 3.1 to 0.1 second.

7 © UCLES 2011 0653/51/O/N/11 [Turn over For Examiner's Use (ii) Repeat the experiment for θ = 10° a further four times and record the results in Table 3.1. (iii) Now carry out the experiment five times each for angles of swing θ = 20° and θ = 30° recording all results in Table 3.1. Table 3.1 time for 10 oscillations / s θ = 10° θ = 20° θ = 30° 1 2 3 4 5 average for 10 oscillations / s period, T / s [5] (b) (i) Calculate the average time for 10 oscillations for each angle of swing, θ. Record your averages in Table 3.1. [1] (ii) Calculate the period, T (the time for one oscillation), from the average for 10 oscillations for each angle of swing, θ. Record values of T in Table 3.1. [1]

8 © UCLES 2011 0653/51/O/N/11 For Examiner's Use (c) Use the period T for θ = 10° in Table 3.1 to calculate the acceleration due to gravity, g, using the formula below. (the length of the pendulum, l, must be in metres). T 2 39.5 x l g = g = m / s2 [2] (d) Explain why you timed 10 oscillations in your experiments rather than timing just one oscillation to obtain the period, T, directly. [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 0653/51/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 SCIENCES 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. • 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 51 © University of Cambridge International Examinations 2011 1 (a) (i) splint relights / splint glows brighter ; oxygen / O2 ; [2] (the second mark is tied to a correct observation being given) (ii) 3 reasonably similar readings for fresh yeast B, C and D ; clearly in seconds ; [2] (iii) correct value for (B + C + D) ÷ 3 to a minimum of 1 decimal place unless it is exactly a whole number ; [1] (b) (i) ‘no reaction’ recorded for E in Table 1.1 ; [1] (ii) fresh yeast faster reaction / fresh yeast worked (or reverse statement) ; enzymes (or yeast) denatured (killed / destroyed / made inactive) by boiling ; [2] (c) (i) yes: similar readings ; OR no: different values / too few repeats / difficult to time end point (if this response is seen here it cannot be credited in (c) (ii) as well) / loss of yeast down side of tube ; [max 1] (ii) uneven concentration of yeast ; timing error ; judgement of foam reaching the line ; not all yeast reaches the peroxide ; detergent not controlled ; concentration of hydrogen peroxide ; accuracy of measuring (must be accompanied by reference to scale) ; [max 1] [Total: 10] 2 (a) compound changes name and formula time / s colour A zinc carbonate, ZnCO3 e.g. 31 yellow (when hot) B magnesium carbonate, MgCO3 e.g. 21 (remains) white C unknown metal carbonate, XCO3 e.g. 28 (green to) black (ii) A: a value of time (in seconds) AND yellow / yellow when hot (ignore references to the limewater) ; [1] (iii) B: a value of time AND white / no change / same (ignore references to the limewater) ; C: a value of time AND black (ignore references to the limewater) ; [2]

Page 3 Mark Scheme: Teachers’ version Syllabus Paper IGCSE – October/November 2011 0653 51 © University of Cambridge International Examinations 2011 (iv) 1 (fastest) = one with shortest time 2 = one with intermediate time 3 (slowest) = one with longest time ; [1] (note: this must be consistent with candidates’ results) (v) carbon dioxide / CO2 ; [1] (b) (i) blue ppt. / grey-blue ppt. / green-blue ppt. ; [1] (ii) brown / black solid OR zinc turns brown / black ; bubbles / effervescence / colourless solution / solution less blue / gets hot ; [2] (iii) X = copper / Cu ; (note: do not allow copper(II) / Cu2+) [1] evidence 1 and evidence 2: any two for one mark blue ppt. with NaOH (in (c)(ii)) and / or blue solution in (c) ; copper carbonate is green ; copper oxide is black ; brown solid (in (c)(ii)) ; displacement by zinc gives brown solid ; X is brown ; X does not react with acid ; [max 1] [Total: 10] 3 (a) any five readings (allow full reading from clock) ; any complete column of readings (allow full reading from clock) ; all 15 readings entered (allow full reading from clock) ; average of readings increasing from θ = 10° to 30° ; all readings recorded to 0.1 s ; [5] (b) (i) all 3 averages correctly calculated to at least 1 decimal place ; [1] (ii) all 3 T values calculated correctly to at least 1 decimal place (average ÷ 10) ; [1] (c) use of l = 0.30 m ; correct calculation of g to at least 1 decimal place using correct T from table which must be squared ; [2] (d) any errors are reduced (divided by ten) / reduced effect of timing error ; [1] [Total: 10]