Cambridge IGCSE Science - Combined 0653 — 2016 Oct/Nov Paper 5 · Variant 2

This document consists of 8 printed pages. DC (LK/JG) 129167/2 © UCLES 2016 [Turn over Cambridge International Examinations Cambridge International General Certificate of Secondary Education * 7 2 7 1 1 6 8 1 5 2 * COMBINED SCIENCE 0653/52 Paper 5 Practical Test October/November 2016 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 8. 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. For Examiner’s Use 1 2 3 Total

2 0653/52/O/N/16 © UCLES 2016 1 You are going to test a procedure to investigate an enzyme-catalysed reaction. Hydrogen peroxide is broken down by catalase, an enzyme found in living cells such as celery cells. Oxygen gas is released during the reaction. Read through the procedure below. • Use the syringe to place 2 cm3 of hydrogen peroxide solution in the test-tube. Add a drop of detergent and use the stirring rod to mix well. • Cut a 1.5 cm length from the middle of the celery stick. • Cut this 1.5 cm length into approximately 1 mm slices. Now cut these slices in half as shown in Fig. 1.1. 1 mm slice approximately 1 mm slice 1.5 cm Fig. 1.1 (not to scale) • Add these pieces to the hydrogen peroxide solution in the test-tube. • Use the stirring rod to push the pieces into the solution and immediately start the stopwatch. (a) In Table 1.1, record the height of the liquid and bubbles, to the nearest 0.1 cm, in the test-tube every 2 minutes for 10 minutes. [3] Table 1.1 time / minutes height / cm 2 4 6 8 10

3 0653/52/O/N/16 © UCLES 2016 [Turn over (b) On the grid provided, plot a graph of liquid and bubble height (vertical axis) against time (horizontal axis). Draw a best-fit curve. [4] (c) A student uses this method to investigate the effect of temperature on this enzyme-catalysed reaction. (i) State two variables that the student should keep constant. 1. … 2. … [1] (ii) Suggest which temperatures the student should use. … …[2]

4 0653/52/O/N/16 © UCLES 2016 2 You are going to investigate the reaction between magnesium and copper sulfate solution. You will also find out how the reaction depends on the concentration of the copper sulfate solution. You are provided with copper sulfate of concentration 1.00 X where X is a unit of concentration. (a) (i) Using the thermometer, measure the initial temperature Ti of the copper sulfate solution and record to the nearest half degree in Table 2.1 the initial temperature Ti for concentration 1.00 X. [1] Table 2.1 concentration of copper sulfate initial temperature Ti / °C highest temperature Th / °C temperature change ΔT / °C 1.00 X 0.75 X 0.50 X 0.25 X (ii) • Transfer one of the samples of magnesium into the plastic cup. • Measure 24 cm3 of copper sulfate solution using the 25 cm3 measuring cylinder. • Add this quickly to the magnesium in the plastic cup. • Stir the mixture thoroughly and measure the highest temperature Th reached. • Record to the nearest half degree in Table 2.1 the highest temperature Th for concentration 1.00 X. [1] (iii) Pour the contents of the plastic cup into the large beaker labelled waste and thoroughly rinse out the plastic cup with water. Make a copper sulfate solution of lower concentration, 0.75 X, using the following method. • Measure 6 cm3 of water using the 10 cm3 measuring cylinder and add this to the small beaker. • Measure 18 cm3 of copper sulfate solution using the 25 cm3 measuring cylinder and add this to the water in the small beaker. • Stir the mixture to ensure an even solution. • Measure the initial temperature Ti of this 0.75 X copper sulfate solution and record to the nearest half degree in Table 2.1 the initial temperature Ti for concentration 0.75 X. [1] • Keep this solution for (iv). The volumes used are shown in Table 2.2.

5 0653/52/O/N/16 © UCLES 2016 [Turn over Table 2.2 concentration of copper sulfate volume of copper sulfate / cm3 volume of water / cm3 1.00 X 24 0 0.75 X 18 6 0.50 X 12 12 0.25 X 6 18 (iv) • Transfer another of the samples of magnesium into the plastic cup. • Add the 0.75 X copper sulfate solution, made in (iii), from the small beaker quickly to the magnesium in the plastic cup. • Stir the mixture thoroughly and measure the highest temperature Th reached. • Record to the nearest half degree in Table 2.1, the highest temperature Th for concentration 0.75 X. [1] (v) Repeat (a)(iii) and (a)(iv) using the volumes of water and copper sulfate for 0.50 X copper sulfate solution and then 0.25 X copper sulfate solution as shown in Table 2.2. Record to the nearest half degree in Table 2.1, the initial temperatures Ti and the highest temperatures Th. [2] (b) (i) Calculate the temperature change ΔT during the reaction for each concentration of copper sulfate. Record these values in the last column of Table 2.1. [1] (ii) A student states that the temperature change ΔT for this experiment depends directly on the concentration of the copper sulfate solution used. Suggest whether this is supported by your data in Table 2.1 and justify your answer. … … …[1] (iii) Suggest how the data in Table 2.1 could be presented to show the relationship between concentration and change in temperature. … …[1] (c) Suggest one change to this procedure to improve the accuracy of the results. … …[1]

6 0653/52/O/N/16 © UCLES 2016 3 You are going to find the mass of a piece of modelling clay using a balancing method. You are provided with a metre rule, a pivot and a piece of modelling clay. (a) Mould the piece of modelling clay until it is roughly cube-shaped. Place the modelling clay on the metre rule so that its centre is 15.0 cm from the zero end of the rule, as shown in Fig. 3.1. 0.0 cm 50.0 cm 100.0 cm 15.0 cm a b modelling clay pivot metre rule bench Fig. 3.1 (not to scale) (i) Adjust the position of the pivot so that the rule balances on it. Record to the nearest 0.1 cm the distance a from the centre of the modelling clay to the pivot as shown in Fig. 3.1. a = … cm [1] (ii) Record to the nearest 0.1 cm the distance b from the pivot to the 50.0 cm mark, as shown in Fig. 3.1. b = … cm [1] (iii) Describe how you ensured that the centre of the modelling clay was directly above the 15.0 cm mark on the metre rule. You may draw a diagram, if you wish. … …[1] (b) Use the balance provided to measure the mass M of the metre rule to the nearest gram. M = … g [1]

7 0653/52/O/N/16 © UCLES 2016 (c) Calculate the mass m of the piece of modelling clay using the equation shown. m = M × b a Give your answer to an appropriate number of significant figures. m = … g [2] (d) Use the balance provided to measure the mass of the piece of modelling clay. mass of modelling clay = … g [1] (e) Even if you have carried out the experiment very carefully, your measured mass of the piece of modelling clay may not be equal to your value of m. Suggest two reasons why this might be so. Assume that the balance is accurate. 1. … … 2. … … [2] (f) The experiment is repeated with a heavier piece of modelling clay. State how the distances a and b will change. … …[1]

8 0653/52/O/N/16 © UCLES 2016 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. NOTES FOR USE IN QUALITATIVE ANALYSIS Tests 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 with dilute nitric acid then add aqueous barium nitrate white ppt. Tests 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 Tests for gases gas test and test result ammonia (NH3) turns damp, red litmus paper blue carbon dioxide (CO2) turns limewater milky chlorine (Cl 2) 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. This document consists of 3 printed pages. © UCLES 2016 [Turn over Cambridge International Examinations Cambridge International General Certificate of Secondary Education COMBINED SCIENCE 0653/52 Paper 5 Practical October/November 2016 MARK SCHEME Maximum Mark: 30 Published 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 2016 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 2016 0653 52 © UCLES 2016 1 (a) full set of results ; all results to the same number of decimal places ; evidence that reaction is slowing at end (not linear increments) ; [3] (b) axes labelled with units ; linear scale using at least half the grid ; at least 4 plots correct ± half small square ; best fit curve ; [4] (c) (i) any two (for one mark) from: constant volume of hydrogen peroxide / constant concentration of hydrogen peroxide / constant size of celery / pH / type of celery [1] (ii) at least 5 stated temperatures ; at least two temperatures below 40 °C and two temperatures above 40 °C ; [2] 2 (a) (i) Ti for concentration 1.00 X ; [1] (ii) Th for concentration 1.00 X recorded to nearest half degree AND above Ti ; [1] (iii) Th for concentration 0.75 X recorded AND ∆T for 0.75 X lower than ∆T value for 1.00 X ; [1] (iv) Th for concentration 0.75 X recorded AND ∆T for 0.75°X lower than ∆T value for 1.00°X ; [1] (v) remaining Ti and Th values for 0.50 X and 0.25 X ; ∆T values decrease down table ; [2] (b) (i) all ∆T values recorded and correct for temperatures recorded (minimum three experiments) ; [1] (ii) supports AND evidence e.g. 1.00 X to 0.50 X halves ∆T OR does not support AND evidence e.g. 1.00 X to 0.50 X nowhere near halves ∆T ; [1] (iii) plot a graph ∆T of against concentration ; [1]

Page 3 Mark Scheme Syllabus Paper Cambridge IGCSE – October/November 2016 0653 52 © UCLES 2016 (c) lid / insulation around flask / rinsing (and drying) of small beaker / extra points / more accurate thermometer ; [1] 3 (a) (i) a recorded to the nearest 0.1 cm ; [1] (ii) b value correct (b = 35 – a) ; [1] (iii) note the reading on either side and find mean / measure cube and mark the centre point ; [1] (b) M recorded to the nearest gram ; [1] (c) m correct ; 2 / 3 significant figures [2] (d) mass of clay recorded ; [1] (e) any two from: centre of gravity of the rule not at the 50 cm mark / difficulty in obtaining balance / rounding errors / pivot not perpendicular to edge of rule / centre of gravity of cube not over the mark due to irregular shape ;; [2] (f) a smaller and b larger ; [1]