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

This document consists of 11 printed pages and 1 blank page. IB15 11_0654_52/5RP © UCLES 2015 [Turn over *6722425197* 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 October/November 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/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 reagent, biuret reagent and iodine solution. Before organising your work, read through parts (a), (b) and (c). (a) Complete Table 1.1 to show which food group each test identifies. [3] Table 1.1 test food group identified Benedict’s biuret iodine (b) • Label three test-tubes A, B and C. • Place about 1 cm depth of milk in each test-tube. • Carry out the Benedict’s test on the contents of test-tube A. Record your observations in Table 1.2. • Repeat the procedure using test-tubes B and C for the biuret test and iodine test, recording your observations in Table 1.2. [2] Table 1.2 Tests on milk test observations Benedict’s biuret iodine

3 © UCLES 2015 0654/52/O/N/15 [Turn over (c) • Label another three test-tubes A, B and C. (If you are re-using the test-tubes, rinse them out at this stage.) • Place about 10 grains of rice in each test-tube. • The test-tubes should not be shaken during the test. Look for a colour forming around the grains. • Carry out the Benedict’s test on the contents of test-tube A. Record your observations in Table 1.3. • Repeat the procedure using test-tubes B and C for the biuret test and iodine test, recording your observations in Table 1.3. [2] Table 1.3 Tests on rice test observations Benedict’s biuret iodine (d) Use your results from Tables 1.2 and 1.3 to identify which food groups are present in the milk and rice. Milk contains Rice contains [4] (e) (i) Describe how you can test for the presence of fats in a food. [2] (ii) State what is observed if the result of the test in (e)(i) is positive. [1] (iii) Suggest why the test in (e)(i) may be difficult to carry out on milk. [1]

4 © UCLES 2015 0654/52/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 (e). This is solid R. • Record your observations. observations [2] (b) • Place half a spatula full of solid P for (b) and (c) 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 conclusions. observations conclusions [4]

5 © UCLES 2015 0654/52/O/N/15 [Turn over (c) • Make a solution of half a spatula full of P for (b) and (c) in distilled water in a beaker. If necessary warm the mixture to completely dissolve the solid. • To about 5 cm3 of this solution of P for (b) and (c), add an equal volume of barium chloride solution. • Record your observations and conclusions. observations conclusions [2] (d) The reaction between P for (b) and (c) 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. (i) Test some of solution Q with red and blue litmus papers. Record your observations. observations [1] (ii) To 5 cm3 of solution Q, add a spatula full of calcium carbonate powder. Record your observations. observations [1] (iii) The hydrochloric acid provided has the same concentration as solution Q. To 5 cm3 of this hydrochloric acid add a spatula full of calcium carbonate powder. Using your observations, compare the speed of this reaction with that seen in (d)(ii). [1] (iv) Using your results in (d)(i), (ii) and (iii), make conclusions about the properties of compound Q. conclusions [1]

6 © UCLES 2015 0654/52/O/N/15 (e) (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]

7 © UCLES 2015 0654/52/O/N/15 [Turn over Please turn over for Question 3.

8 © UCLES 2015 0654/52/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 / potential difference V / 15.0 20.0 25.0 40.0 60.0 100.0 (ii) In Table 3.1 insert the units for current and potential difference. [1] (iii) 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. [3]

9 © UCLES 2015 0654/52/O/N/15 [Turn over (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). [4] (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]

10 © UCLES 2015 0654/52/O/N/15 (e) Give one possible source of inaccuracy in the experiment and the precaution you took to minimise it. source of inaccuracy precaution [2]

11 © UCLES 2015 0654/52/O/N/15 BLANK PAGE

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/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 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 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 0654 52 © Cambridge International Examinations 2015 1 (a) test food group identified Benedict’s reducing sugar ; biuret protein ; iodine starch ; [3] (b) tests on milk: test observations Benedict’s yellow / red / orange biuret purple iodine orange / no change all three correct = 2, two correct = 1, one correct = 0 ;; [2] (c) tests on rice: test observations Benedict’s blue / no change biuret purple iodine blue-black / black all three correct = 2, two correct = 1, one correct = 0 ;; [2] (d) (mark independently to observations) milk contains: reducing sugar ; protein ; rice contains: protein ; starch ; [max 4] (allow: ecf from (a) if groups muddled) (allow: ecf ‘sugar’ from (a))

Page 3 Mark Scheme Syllabus Paper Cambridge IGCSE – October/November 2015 0654 52 © Cambridge International Examinations 2015 (e) (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] (iii) milk is cloudy / milky / cannot see the result / AW (independent mark) ; [1] [Total: 15] 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) not a carbonate / not CO3 2– ; acidic gas ; [4] (c) no visible reaction / no ppt. ; not a sulfate / not SO4 2– ; [2] (d) (i) blue litmus turns red ; [1] (ii) effervescence / fizzing / bubbles ; [1] (iii) (HCl) faster effervescence / more fizzing / more bubbles (than Q) ; [1] (iv) (weakly) acidic ; [1] (e) (i) effervescence / fizzing / bubbles ; (limewater becomes) milky / white ppt. ; [2] (ii) calcium carbonate / CaCO3 / calcium hydrogen carbonate / Ca(HCO3)2 ; [1] [Total: 15] 3 (a) (i) realistic I value recorded for 15.0 cm ; realistic V value recorded for 15.0 cm ; [2] (ii) units both correct (symbols or names) ; [1] (iii) 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. ; I values decreasing and V values increasing ; [3] (allow: one pair of identical values)

Page 4 Mark Scheme Syllabus Paper Cambridge IGCSE – October/November 2015 0654 52 © Cambridge International Examinations 2015 (b) axes labelled with units ; suitable choice of scales (⩾ half the grid used) ; at least 5 plots correct to half a small square ; good best-fit line judgement ; [4] (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 2 or 3 significant figures ; [1] (ecf from (c)) (e) reading meter scales ; observe perpendicularly (owtte) ; OR measuring the length of wire ; observe perpendicularly / repeat for increasing lengths of wire / pull wire straight ; [max 2] (allow: 1 mark for not switching off between readings / battery might run down) (ignore: crocodile clips) [Total: 15]