Cambridge IGCSE Science - Combined 0653 — 2015 Oct/Nov Paper 5 · Variant 2

This document consists of 8 printed pages. IB15 11_0653_52/2RP © UCLES 2015 [Turn over *1115927352* For Examiner's Use 1 2 3 Total Cambridge International Examinations Cambridge International General Certificate of Secondary Education COMBINED SCIENCE 0653/52 Paper 5 Practical Test October/November 2015 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.

2 © UCLES 2015 0653/52/O/N/15 1 You are going to carry out some tests to determine the food groups present in rice and milk. You are provided with Benedict’s solution and iodine solution. (a) Complete the second row of Table 1.1 to show which food group each test identifies. [2] (b) • Label two test-tubes, A and B. Place about 10 grains of the rice in test-tube A and about 1 cm depth of milk in test-tube B. • Dry rice grains should be placed in the bottom of the test-tube and should not be shaken during the test. Look for a colour forming around the grains. • Filling the test-tube to 1 cm depth with the milk or rice will be sufficient for testing each time. Carry out Benedict’s test on both the milk and rice. Record your results in the second column of Table 1.1. Repeat the procedure using clean test-tubes for the iodine test. Record your observations in the third column of Table 1.1. [3] Table 1.1 reagent Benedict’s test iodine test food group(s) present food group tested for colour obtained with milk colour obtained with rice (c) Use your results from (b) to complete the final column of Table 1.1 to indicate the food groups present in the milk and rice. [2] (d) (i) The presence of fats in food can be tested by rubbing the food onto brown paper. If there is fat present it leaves a translucent mark on the paper. Describe another way to test for fats in food. [2] (ii) State what is observed if the result of the test in (d)(i) is positive. [1]

3 © UCLES 2015 0653/52/O/N/15 [Turn over Please turn over for Question 2.

4 © UCLES 2015 0653/52/O/N/15 2 Solid P is a calcium salt. You are going to carry out tests on solid P and identify some products of its reactions. (a) • Remove the stopper from the hard-glass test-tube containing solid P for (a). • Heat strongly for 2 minutes and hold a lighted splint at the mouth of the test-tube while heating. • Leave to cool and keep the remaining solid for testing in (d). This is solid R. • Record your observations. observations [2] (b) • Place half a spatula full of solid P for (b) in a test-tube and add about 5 cm3 nitric acid. Gently heat the test-tube and hold pieces of damp red and blue litmus paper in the mouth of the test-tube, being careful not to touch the sides of the test-tube with the paper. • Stop heating if the mixture starts to boil. • Record your observations and a conclusion. observations conclusion [3]

5 © UCLES 2015 0653/52/O/N/15 [Turn over (c) The reaction between P for (b) and nitric acid in (b) produces two compounds. These are a different calcium salt and compound Q. You are provided with a solution of Q in distilled water. To 5 cm3 of solution Q, add a spatula full of calcium carbonate powder. Record your observations and conclusions about solution Q. observations conclusions [2] (d) (i) When the remaining solid from (a), compound R, has cooled, add hydrochloric acid and test any gas produced by passing it through limewater. Record your observations. observations [2] (ii) Suggest an identity for compound R. compound R is [1]

6 © UCLES 2015 0653/52/O/N/15 3 You are going to measure the resistance of a power source. The circuit shown in Fig. 3.1 has been set up for you. V power source switch 0 100 X resistance wire A C Fig. 3.1 (a) (i) Close the switch and connect the crocodile clip C to the resistance wire at a distance d of 15.0 cm from end X. Record in Table 3.1 the current I flowing through the wire and the potential difference V. Switch off the circuit. [2] Table 3.1 distance d / cm current I / A potential difference V / V 15.0 20.0 25.0 40.0 60.0 100.0 (ii) Repeat (a)(i) for values of d of 20.0 cm, 25.0 cm, 40.0 cm, 60.0 cm and 100.0 cm. Record in Table 3.1 your values of I and V for each d. Remember to switch off between readings. [2]

7 © UCLES 2015 0653/52/O/N/15 (b) Plot a graph of V (vertical axis) against I. Draw the best-fit straight line. You do not need to start your graph at (0, 0). I / A V / V [3] (c) Calculate the gradient of your line. Show all working and indicate on your graph the values you chose to enable the gradient to be calculated. gradient = [2] (d) The positive value of the gradient of your line is equal to the resistance of the power source. Write down the resistance of the power source to an appropriate number of significant figures. resistance of power source = Ω [1]

8 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 0653/52/O/N/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 October/November 2015 series 0653 COMBINED SCIENCE 0653/52 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 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 – October/November 2015 0653 52 © Cambridge International Examinations 2015 1 (a) reagent Benedict’s iodine solution food group tested for (reducing) sugar ; starch ; [2] (b) reagent Benedict’s iodine solution colour with milk yellow / red / orange orange colour with rice blue blue-black / black full set of results recorded for milk and rice ; all correct for milk ; all correct for rice ; [3] (c) food group(s) present colour with milk (reducing) sugar ; colour with rice starch ; (mark independently to observations) (allow: ecf from (a) if groups muddled) [2] (d) (i) dissolve in / mix with ethanol ; add water ; [2] (ii) cloudy / milky / emulsion (this mark linked to (e)(i) being at least partly correct) ; [1] [Total: 10] 2 (a) vapour burns / blue flame / flammable gas / splint remained lit ; solid goes grey / black / darkens / condensation ; [2] (b) no effervescence / no fizzing / no bubbles ; pungent smell / blue litmus turns red ; (do NOT allow this mark if has red litmus to blue) (conclusion) acidic gas / not a carbonate ; [3]

Page 3 Mark Scheme Syllabus Paper Cambridge IGCSE – October/November 2015 0653 52 © Cambridge International Examinations 2015 (c) effervescence / fizzing / bubbles ; acid ; [2] (d) (i) effervescence / fizzing / bubbles ; (limewater becomes) milky / white ppt. ; [2] (ii) calcium carbonate / CaCO3 / calcium hydrogen carbonate / Ca(HCO3)2 ; [1] [Total: 10] 3 (a) (i) realistic I value recorded for 15 cm ; realistic V value recorded for 15 cm ; [2] (ii) all I values < 1.5 A and to at least 2 d.p. ; all V values < 2.5 V and to at least 1 d.p. ; [2] (b) suitable choice of scales (⩾ half the grid used) ; at least 5 plots correct to half a small square ; good best-fit line judgement ; [3] (c) indication on graph of how data obtained and at least half of line used ; correct calculation for triangle method using data from graph ; [2] (d) answer equals (c) recorded to 2or 3 significant figures ; [1] (ecf from (c)) [Total: 10]