Cambridge IGCSE Science - Combined 0653 — 2011 Oct/Nov Paper 6 · Variant 1

This document consists of 17 printed pages and 3 blank pages. IB11 11_0653_61/5RP © UCLES 2011 [Turn over *2710894992* For Examiner's Use 1 2 3 4 5 6 Total UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS International General Certificate of Secondary Education COMBINED SCIENCE 0653/61 Paper 6 Alternative to Practical October/November 2011 1 hour Candidates answer on the Question paper No Additional Materials are required. 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 soft pencil for any diagrams, graphs, tables or rough working. Do not use staples, paper clips, highlighters, glue or correction fluid. DO NOT WRITE IN ANY BARCODES. Answer all questions. 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 0653/61/O/N/11 For Examiner's Use 1 (a) A student carried out an investigation into the effect of high temperature on catalase enzyme activity. Catalase is an enzyme found in many tissues which catalyses the decomposition of hydrogen peroxide to produce a gas. • The student labelled four large test-tubes tubes A, B, C and D and drew a line 1 cm from the top of each test-tube. • He placed 10 cm3 of hydrogen peroxide and a drop of detergent into each test-tube. • He placed a 5 g piece of raw liver into tubes A, B and C. This immediately caused a chemical reaction to occur and ‘foam’ was produced. • He recorded the time it took for the foam to reach the pen line. The stopclock readings are shown in Fig. 1.1 below. A B C Fig. 1.1 (i) Using Fig. 1.1, record in Table 1.1 the times taken, in seconds, for the foam to reach the pen line of test-tubes A, B and C. Table 1.1 liver type raw boiled test-tube A B C D time taken / s N/R [3] (ii) A glowing splint was placed into the ‘foam’. The splint began to burn brightly again. Name the gas that was produced by the decomposition of the hydrogen peroxide. [1]

3 © UCLES 2011 0653/61/O/N/11 [Turn over For Examiner's Use (iii) Calculate the average time taken, in seconds, for the foam to reach the pen line for the reactions in tubes A, B and C. [1] The experiment was repeated using test-tube D and a 5 g piece of liver that had been boiled for one minute. A few bubbles were seen in the mixture. This was recorded in Table 1.1 as N/R (No reaction). (iv) Compare the results for the raw and boiled liver. Explain the reasons for the difference in results. [2] (b) (i) Suggest a reason why a few bubbles were produced in test-tube D. [1] (ii) Suggest which conditions should be kept constant in this experiment. [2]

4 © UCLES 2011 0653/61/O/N/11 For Examiner's Use 2 The teacher has asked a student to investigate the speed of thermal decomposition of three metal carbonates, A, B and C. Carbonate C contains the unknown metal X. Fig. 2.1 shows the apparatus she is using. The metal carbonate decomposes when it is heated. The gas given off turns the limewater milky. limewater metal carbonate A heat Fig. 2.1 • The student places about 1 cm depth of metal carbonate A in the hard-glass test-tube. • She heats it and at the same time starts a stopclock. • When the limewater turns milky, she stops the clock and records the result in Table 2.1. • She records any colour change of the metal carbonate in Table 2.1. • She repeats the experiment using metal carbonates B and C. Table 2.1 metal carbonate time taken for limewater to turn milky / s colour change A zinc carbonate white at first, turns yellow and then becomes white on cooling B magnesium carbonate white at first, stays white C carbonate of unknown metal X green at first, turns black

5 © UCLES 2011 0653/61/O/N/11 [Turn over For Examiner's Use (a) Fig. 2.2 shows the stopclocks used for each test. The dials show the time taken by each carbonate to decompose and turn the limewater milky. 5 0 10 15 20 40 25 35 30 45 50 55 metal carbonate A 5 0 10 15 20 40 25 35 30 45 50 55 metal carbonate B 5 0 10 15 20 40 25 35 30 45 50 55 metal carbonate C Fig. 2.2 (i) Read the stopclock dials and record the times in Table 2.1. [3] (ii) Write the letters A, B or C, listing the metal carbonates in order of their speed of thermal decomposition. 1 (fastest) 2 3 (slowest) [1] (b) The student wants to find out the name of the unknown metal X found in metal carbonate C. When the heated test-tube has cooled, she places the black residue in a beaker and adds 20 cm3 of dilute sulfuric acid, stirring the mixture and then filtering it. (i) Draw a diagram to show how she filters the mixture. [1]

6 © UCLES 2011 0653/61/O/N/11 For Examiner's Use The filtered solution is blue. She adds aqueous sodium hydroxide to 2 cm3 of the filtrate. There is a light blue precipitate. (ii) Suggest the name of the light blue precipitate. [1] (iii) Suggest the name of the black residue left after metal carbonate C was heated. [1] (c) The teacher gives the student a small piece of each of the three metals, zinc, magnesium and unknown metal X. She adds dilute hydrochloric acid to the metals in three separate test-tubes, shown in Fig. 2.3. zinc magnesium unknown metal X Fig. 2.3 On Fig. 2.3, draw the bubbles of gas, if any, that are produced in each test-tube. Your drawing should show clearly the different reactivity of each metal. [2] (d) Compare your drawing in Fig. 2.3 with your answer to part (a)(ii). Can the different reactivity of the metals be used to predict the speed of thermal decomposition of the metal carbonates? Explain your answer. [1]

7 © UCLES 2011 0653/61/O/N/11 [Turn over BLANK PAGE Please turn over for Question 3.

8 © UCLES 2011 0653/61/O/N/11 For Examiner's Use 3 A student is investigating how T, the time for one swing of a pendulum, is affected by the angle of swing. The pendulum is 30 cm long and suspended from a pin. The arrangement of apparatus is shown in Fig. 3.1. 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 pin angle of swing Fig. 3.1 • The student holds the pendulum so that the angle of swing is 10°, as in Fig. 3.1. • He releases the pendulum and starts a stopclock. • He allows the pendulum to swing 10 times. • He records the time for 10 complete swings in Table 3.1. • He repeats the experiment using different angles of swing. Table 3.1 experiment 1 2 3 4 5 6 7 8 angle of swing / degrees 10 25 35 40 85 time for 10 swings / s 11.4 11.2 11.6 11.5 11.3 time, T for 1 swing / s

9 © UCLES 2011 0653/61/O/N/11 [Turn over For Examiner's Use (a) (i) Fig. 3.2 shows the angle of swing and the digital stopclock for three more experiments. Read the angle of swing and the time for each angle of swing. Record the results in Table.3.1. 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 angle of swing experiment 5 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 angle of swing experiment 6 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 angle of swing experiment 7 Fig. 3.2 [3] (ii) Complete Table 3.1 by finding the time, T, for one swing of the pendulum for each experiment. [1]

10 © UCLES 2011 0653/61/O/N/11 For Examiner's Use (iii) Use the results for T in Table 3.1 to find the average time, Tav, for one swing of the pendulum for all experiments. Tav = s [1] (b) Do the results show that T, the time for one swing, is affected by the angle of swing? Explain your answer. [1] (c) Explain how the student can make the results of his experiment more reliable. [1] (d) The student is using a pendulum that is 30 cm long. Convert this value from centimetres to metres. length of pendulum, l = m [1] (e) Use the value of l from part (d), Tav from part (a)(iii) and the formula below to calculate g, the acceleration due to gravity. (Tav) 2 39.5 x l g = g = m / s2 [2]

11 © UCLES 2011 0653/61/O/N/11 [Turn over BLANK PAGE Please turn over for Question 4.

12 © UCLES 2011 0653/61/O/N/11 For Examiner's Use 4 (a) A student was given a solution and was told that it contained the enzyme amylase. Amylase is found in saliva. It catalyses the breakdown of starch into sugar. The student wanted to confirm that the solution contained amylase by testing whether it could break down starch solution. • He put some starch solution into test-tubes A and B. He added amylase solution to tube A. He added an equal volume of water to test-tube B as a control. • After waiting for 10 minutes he added a few drops of iodine solution to each test-tube. • The results showed that the starch had been completely broken down in test-tube A but had not broken down in test-tube B. Describe the colours of the solutions after testing with iodine. test-tube A test-tube B [2] (b) The student believed that the activity of amylase is affected by the pH of solution. He did another experiment to confirm this as follows. • He prepared starch solutions of 5 different pH values. • He added amylase solution to the test-tube of pH 4. • He started the timer. • After 15 seconds he used a glass rod to remove a small sample of the test solution. He tested this with iodine. • He used the iodine test to see if starch was still present. If starch was present he repeated the test after a further 15 seconds. • He continued to test the solution every 15 seconds until the test showed that no starch remained. He entered the time taken for the starch to disappear in Table 4.1. • He then repeated the procedure for the remaining pH values. (i) Read the stopclocks in Fig. 4.1 and enter the missing times, in seconds, in Table 4.1. pH 5 pH 8 Fig. 4.1

13 © UCLES 2011 0653/61/O/N/11 [Turn over For Examiner's Use Table 4.1 pH time for starch to disappear / s 4 195 5 6 90 7 90 8 [2] (ii) Plot a graph of time against pH. Draw a smooth curve through your points. 0 2 4 6 8 1 3 5 7 200 180 160 140 120 100 80 60 40 20 0 pH time / s [2] (iii) Over which pH range is the activity of the amylase greatest? pH range = [1]

14 © UCLES 2011 0653/61/O/N/11 For Examiner's Use (c) (i) The student knew that the experiment could be improved to obtain a more accurate value of pH for the greatest activity. List two improvements he could make to the experiment. 1 2 [2] (ii) Choose one of the improvements you have suggested. Explain why it would improve the accuracy of pH of greatest activity. [1]

15 © UCLES 2011 0653/61/O/N/11 [Turn over BLANK PAGE Please turn over for Question 5.

16 © UCLES 2011 0653/61/O/N/11 For Examiner's Use 5 The teacher gives her students five gas-jars, each containing a different gas. The gas-jars are labelled A, B, C, D and E. She also gives them a key to use to determine the name of each gas. The key is shown in Fig. 5.1. five colourless gases test 1: does the gas easily dissolve in water? test 2: is the solution acidic or alkaline? test 3: does the gas support combustion? test 4: does the gas burn in air? Yes No acidic alkaline sulfur dioxide ammonia Yes No hydrogen nitrogen No Yes oxygen Fig. 5.1 Fig. 5.2 shows a gas-jar of gas that has been inverted and placed in a bowl of water with its lid still on. gas water lid Fig. 5.2 One student is testing one of the gases to see if it will dissolve in water. He places the mouth of the gas-jar in the water as shown in Fig. 5.2. He then removes the lid of the gas-jar. (a) (i) Describe what he observes if the gas does dissolve in the water in the bowl. [1] (ii) Explain why this happens. [1]

17 © UCLES 2011 0653/61/O/N/11 [Turn over For Examiner's Use (b) Assuming that the gas in the gas-jar in Fig. 5.2 has dissolved in the water, explain how you can carry out test 2, shown in Fig. 5.1, on the solution in the bowl. Give the results for an acidic gas and an alkaline gas. test 2 [1] result for acid gas [1] result for alkaline gas [1] (c) Explain how you would carry out test 3, shown in Fig. 5.1, on a gas-jar of gas. Describe the result for oxygen. test 3 [1] result for oxygen [1] (d) Explain how you would carry out test 4, shown in Fig. 5.1, on a gas-jar of gas. Describe the result for hydrogen. test 4 [1] result for hydrogen [1] The conclusions that the students made, after carrying out all of the tests, are shown in Table 5.1. Table 5.1 gas A gas B gas C gas D gas E oxygen sulfur dioxide nitrogen ammonia hydrogen (e) Suggest the names of two of the gases listed in Table 5.1 that will react together, when mixed at room temperature and pressure, without using either a catalyst or a flame. and [1]

18 © UCLES 2011 0653/61/O/N/11 For Examiner's Use 6 A student is comparing the electrical resistances of two pieces of resistance wire, X and Y. The wires are made from the same alloy but are different in length and thickness. The pieces of wire are shown in Fig. 6.1. wire X wire Y Fig. 6.1 (a) Measure the lengths of wire X and wire Y in centimetres to the nearest millimetre. Record the lengths in Table 6.1. Table 6.1 wire X Y length / cm thickness / millimetres 0.2 0.9 [2] The student uses the circuit shown in Fig. 6.2 to find the resistance of the wires. meter meter resistance wire X or Y Fig.6.2 (b) (i) Complete the diagram in Fig. 6.2 by writing the letters A and V to show the ammeter and voltmeter in the correct places. [1]

19 © UCLES 2011 0653/61/O/N/11 [Turn over For Examiner's Use (ii) Fig. 6.3 shows the voltmeter and ammeter readings when one of the wires is connected in the circuit. Read the meters and record the readings in column 1 of Table 6.2. 5 0 V 0.5 0 A 0.1 0.2 0.3 0.4 Fig. 6.3 Table 6.2 column 1 column 2 current / amps 2.5 voltage / volts 0.5 resistance / ohms 0.2 [2] (iii) Use the data in column 1 of Table 6.2 to calculate the resistance of this wire. Record the resistance in Table 6.2. [2] (c) The student has forgotten which wire he used to record the data in each column of Table 6.2. (i) Decide which wire, X or Y, produced the results shown in column 1, and which wire produced the results shown in column 2. Complete the sentences. Column 1 shows the data for wire Column 2 shows the data for wire [1]

20 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 0653/61/O/N/11 For Examiner's Use (ii) Explain your choice in (c)(i) by stating how the lengths and thicknesses of the two wires affect their electrical resistance. [2]

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 SCIENCE 0653/61 Paper 6 (Alternative to Practical), maximum raw mark 60 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 61 © University of Cambridge International Examinations 2011 1 (a) (i) 57 ; 63 ; 53 ; (no tolerance) [3] (ii) oxygen ; [1] (iii) 57.7 ; [1] (iv) boiled gives no reaction and raw gives more bubbles / faster reaction ; (boiling) denatures enzyme / catalase ; [2] (b) (i) not heated fully through / long enough / not all enzyme denatured / some enzyme still present ; [1] (ii) surface area of liver ; temperature ; pH ; detergent ; concentration of hydrogen peroxide solution ; [max 2] [Total: 10] 2 (a) (i) 37 s ; 52 s ; 19 s ; (no tolerance) [3] (ii) C A B (correct order) ; [1] (b) (i) filter funnel showing filter paper and vessel to collect filtrate ; (labels not required) [1] (ii) copper hydroxide ; [1] (iii) copper oxide ; [1] (c) more bubbles from magnesium than from zinc ; no bubbles from metal X ; [2] (d) the carbonate of the more reactive metal does not decompose as easily / owtte ; [1] [Total: 10]

Page 3 Mark Scheme: Teachers’ version Syllabus Paper IGCSE – October/November 2011 0653 61 © University of Cambridge International Examinations 2011 3 (a) (i) 45 60 75 11.3 ; 11.2 ; 11.7 ; (1 mark for each pair) [3] (ii) all values correct (line 2 divided by 10) ; (allow 1 error) (allow e.c.f. from 3(a)(i)) [1] (iii) 1.14 ; (e.c.f.) [1] (b) (no), all results are within experimental error / close together / no correlation / trend / pattern ; OR (yes), because all results are not the same ; [max 1] (c) repeat (each part of the experiment several times) and find the average ; [1] (d) 0.3 ; [1] (e) g = 2 1.14 0.3 3.95 × ; (e.c.f.) = 9.1 (m / s2) ; [2] [Total: 10] 4 (a) brown ; blue / black ; [2] (b) (i) 135 ; 105 ; (no tolerance) [2] (ii) plotting correct (allow e.c.f.) ; curve drawn ; [2] (iii) pH 6 – 7; [1] (c) (i) use pH values between 6 and 7 / owtte ; take samples more frequently ; [2] (ii) would find activity / more information about intermediate values ; OR may find endpoint at a time between 15 s intervals ; [max 1] [Total: 10]

Page 4 Mark Scheme: Teachers’ version Syllabus Paper IGCSE – October/November 2011 0653 61 © University of Cambridge International Examinations 2011 5 (a) (i) water enters the gas-jar ; [1] (ii) air pressure pushes the water from the bowl into the gas-jar / air pressure greater outside (the jar) ; OR water enters to take the place of the dissolved gas ; [max 1] (b) add named indicator ; result for acid: colour to match indicator ; result for alkali: colour to match indicator ; [3] (c) place glowing / lit splint into gas ; result: splint bursts into flame / relights / burns brighter ; [2] (d) place burning splint into gas ; result: gas burns accept ‘pop’ ; [2] (e) ammonia and sulfur dioxide (any order) ; [1] [Total: 10] 6 (a) 12.1 cm ; 10.1 cm ; (both ± 1 mm) [2] (b) (i) A and V in correct places ; (no mark if reversed) [1] (ii) 4.5 V ; 0.3 A ; (no tolerance) [2] (iii) R = V/I ; R = 4.5 / 0.3 = 15 (ohms) ; (e.c.f.) [2] (c) (i) column 1 shows the data for wire X ; column 2 shows data for wire Y ; [1] (ii) The thinner the wire, the greater the resistance / owtte ; The longer the wire, the greater the resistance / owtte ; (allow cross-sectional area for thickness of wire.) [2] [Total: 10]