Cambridge IGCSE Physical Science 0652 — 2002 Oct/Nov Paper 6 · Variant 1

TIME 1 hour INSTRUCTIONS TO CANDIDATES Write your name, Centre number and candidate number in the spaces at the top of this page. Answer all questions. Write your answers in the spaces provided on the question paper. INFORMATION FOR CANDIDATES The number of marks is given in brackets [ ] at the end of each question or part question. International General Certificate of Secondary Education CAMBRIDGE INTERNATIONAL EXAMINATIONS PHYSICAL SCIENCE 0652/6 PAPER 6 Alternative to Practical OCTOBER/NOVEMBER SESSION 2002 1 hour Candidates answer on the question paper. No additional materials are required. This question paper consists of 11 printed pages and 1 blank page. (NH/PW) S16250/4 © CIE 2002 [Turn over Candidate Centre Number Number Candidate Name FOR EXAMINER’S USE 3 2 1 4 7 TOTAL 6 5 www.XtremePapers.com

2 0652/6 O/N/02 1 When aqueous sodium thiosulphate reacts with acid, a precipitate of sulphur is formed. An experiment was done to investigate how the time taken for this reaction varied with temperature. • 50 cm3 of aqueous sodium thiosulphate, was placed in a conical flask. • The conical flask was warmed to a temperature of 30 °C. • 5 cm3 of hydrochloric acid was added to the conical flask and a clock was started. • The flask was placed on top of a black cross drawn on white paper, as shown in Fig. 1.1. • The time taken for enough precipitate to form, so that the cross could not be seen, was noted in Fig. 1.2. Fig. 1.1 Fig. 1.2 The procedure was repeated at four different temperatures. The times taken for the precipitates to form are shown in Fig. 1.3. Fig. 1.3 (a) Read the clock dials in Fig. 1.3 and record the times in Fig. 1.2. [2] 15 30 45 0 15 30 45 0 15 30 45 15 30 45 40°c 50°c 60°c 70°c 0 0 black cross on paper 50cm3 aqueous sodium thiosulphate + 5cm3 hydrochloric acid For Examiner’s Use temperature/°C 30 75 40 50 60 70 time taken for cross to disappear/s

3 0652/6 O/N/02 [Turn over (b) On the grid provided, plot a graph of time (vertical axis) against temperature, and draw a smooth curve through the points. [4] (c) Describe the relationship between the temperature and the time taken for the reaction to occur. … …[1] (d) Use your graph to find the temperature required to give a reaction time of 50 seconds. Show how you do this on the graph. temperature = …°C [1] (e) The graph you have plotted does not show the relationship between the rate of reaction and the temperature. Briefly explain what you would do with the results to show such a relationship. … …[1] (f) Briefly describe how you would carry out an experiment at 0 °C to find the reaction time. … …[1] For Examiner’s Use

4 0652/6 O/N/02 2 The teacher demonstrated the use of a Geiger-Muller tube, connected to a scaler, to investigate a radioactive sample. The apparatus is shown in Fig. 2.1. Fig. 2.1 In each experiment, the radioactivity was counted for five minutes or for ten minutes. Fig. 2.2, shows how the count rate was changed when sheets of paper, aluminium and lead were placed in front of the detector and when the radioactive source was removed. Fig. 2.2 (a) Complete the final column of the table by calculating the counts per minute. [2] (b) Explain the reason for experiment 6. … …[1] ON OFF COUNT radioactive source lead shield sheet of paper detector For Examiner’s Use expt. no 1 2 3 4 5 6 nothing was placed between the source and the detector a sheet of paper was placed between the source and the detector a 1 mm sheet of aluminium was placed between the source and the detector a 3 mm thick sheet of aluminium was placed between the source and the detector a 3 mm sheet of lead was placed between the source and the detector the source was taken away from the apparatus how the count was done total count 3875 1760 640 335 170 90 time of count/minutes 5 5 5 5 10 10 counts per minute

5 0652/6 O/N/02 [Turn over (c) Use the data in the table to suggest (i) what type of radiation was detected in experiment 5, … [1] (ii) what types of radiation were stopped by the aluminium in experiment 4, … and … [2] (iii) what type of radiation was stopped by the paper in experiment 2. … [1] (d) State one rule for the safety of the teacher and the class when a radioactive source is being used in an experiment. …[1] (e) State how the radioactive source should be stored when it is not in use. … …[2] For Examiner’s Use

6 0652/6 O/N/02 3 A student did an experiment to find the energy change when a weighed mass of solid Z dissolved in a measured volume of water in a glass beaker. The energy change during the reaction was shown by the change in temperature of the beaker and the water. Fig. 3.1 shows the balance reading when the beaker was weighed. Fig. 3.2 shows the balance reading when the beaker containing solid Z was weighed. Fig. 3.3 shows the temperature of the 25 cm3 of water. Fig. 3.4 shows the temperature of the water after solid Z had dissolved. Fig. 3.1 Fig. 3.2 Fig. 3.3 Fig. 3.4 (a) Read the balance and the thermometer scales and then complete Fig. 3.5. [5] Fig. 3.5 20 19 18 17 15 16 27 26 25 24 22 23 42 41 g 39 38 37 g For Examiner’s Use mass of beaker mass of beaker + solid Z mass of solid Z temperature of the 25 cm3 of water temperature of the solution of Z in water M1 = …g M2 = …g M3 = …g T1 = …°C T2 = …°C

7 0652/6 O/N/02 [Turn over (b) Calculate the temperature change, T2 – T1. temperature change, T2 – T1 = …°C [1] (c) (i) Convert M1, the mass of the beaker in grams, into kilograms. mass of the beaker in kilograms = …kg [1] (ii) Multiply this mass by 670. This gives the heat energy stored by the beaker, H joules, for each degree Celsius change. heat energy stored by the beaker, H = … joules [1] (d) Using your answers to (b) and (c) (ii), calculate the total heat energy change when solid Z dissolved in water, using the formula below. total heat energy change = (T2 – T1) x (H + 105) joules total heat energy change = … joules [1] (e) Is the dissolving of Z in water exothermic or endothermic? Explain your answer. … …[1] For Examiner’s Use

8 0652/6 O/N/02 4 Lemon juice contains citric acid which gives it a sour taste. Citric acid reacts with sodium hydroxide to form the salt sodium citrate. Study the information given in Fig. 4.1 and Fig. 4.2. Use the information to answer the questions which follow. Fig. 4.1 Fig. 4.2 (a) Describe how you could make a sample of citric acid crystals from the juice of a lemon. … … … …[3] (b) Describe how you could make a sample of sodium citrate crystals using the citric acid crystals from the experiment in (a) and the indicator named in Fig. 4.2. You may assume that sodium hydroxide solution and the usual laboratory apparatus are available. … … … … … … … … … …[7] For Examiner’s Use name of substance citric acid sodium citrate appearance white crystals white crystals solubility in water soluble soluble name of indicator phenolphthalein colour at pH5 colour at pH9 purple colourless

9 0652/6 O/N/02 [Turn over 5 The teacher asks a student to place switches in an electrical circuit so that three lamps can be controlled. Fig. 5.1 shows the circuit without the switches. Fig. 5.1 (a) In the space below draw the circuit symbol for an open switch. [1] (b) On Fig. 5.1 draw and label a switch to (i) switch off all of the lamps at the same time, labelled S1 [1] (ii) switch off lamp 1 but leave lamps 2 and 3 on – labelled S2 [1] (iii) switch off lamps 2 and 3 at the same time, but leave lamp S1 on, labelled S3 [1] (c) The student wants to measure the voltage provided by the battery. On Fig. 5.1 draw a symbol for a voltmeter in the correct place to measure this voltage. [2] Lamp 1 Lamp 2 Lamp 3 For Examiner’s Use

10 0652/6 O/N/02 6 A student was given three colourless liquids in separate test tubes. Liquid A was dilute sulphuric acid, liquid B was aqueous calcium hydroxide and liquid C was purified water. He performed the tests shown in Fig. 6.1 and made the observations shown. Complete the missing conclusions that the student should make and, in the final column of the table, identify which liquid A, B or C was being used for the test in each case: Fig. 6.1 For Examiner’s Use (a) (b) (c) (d) (e) test liquid added to sodium carbonate liquid tested with pH paper boiling point of liquid tested liquid added to barium nitrate solution carbon dioxide bubbled through the liquid liquid turned milky insoluble carbonate formed pH paper turned blue 100 °C white precipitate gas evolved that turned limewater milky the gas was … … [1] the pH was … … [1] the precipitate was … … [1] [1] [1] [1] [1] [1] observations conclusions liquid used? A, B or C?

11 0652/6 O/N/02 7 A student was asked to find out which coloured inks were present in a mixture, M. She was given a sample of M. She was also given blue, yellow, green and two red inks, which were all single substances. Three of these inks were present in M. In addition, the student was provided with the following apparatus: a sheet of chromatography paper a pencil a ruler a beaker teat pipettes a paper clip Explain how the student could use the apparatus to find out which three of the five coloured inks were present in the mixture M. You may draw diagrams to help your explanation if you wish. [6] For Examiner’s Use

CAMBRIDGE INTERNATIONAL EXAMINATIONS NOVEMBER 2002 INTERNATIONAL GCSE UNIVERSITY of CAMBRIDGE tS Local Examinations Syndicate

IGCSE Examinations — November 2002 0652 | Page 1 - Mark Scheme + Syllabus | Paper _| 6 Q. No. Marking Scheme Details @) (b) (© @) © @ Part Mark Readings : 39s, 22s, 13s, 7s (No tolerance) (4 correct 2 marks, 2/3 correct 1 mark, 1/0 correct zero) Suitable labeled axes (at least % grid) [1] (time must be vertical or mark lost) All points plotted correctly [2] (one mark lost for each incorrectly plotted point to minimum 0) Smooth curve drawn [1] (tramlines = 0; straight line = 0) (allow ecf from plotted points). * the higher the temperature the shorter the time (OWTTE) (allow converse) allow ‘the higher the temperature the faster the (rate of the) reaction’ value depends upon candidate’s graph (allow ecf from plotted points) plot graph of 1/time against temperature (or determine gradients from curve) surround the flask with ice do NOT allow — ‘put in fridge/freezer’ or ‘cool’

Page 2 Mark Scheme Syllabi P; IGCSE Examinations — November 2002 "os2 + Q. No. Marking Scheme Details Part Mark 2. Counts/minute: 775, 352, 128, 67, 17, 9 2 5 or 6 correct 2 marks; 3 or 4 correct 1 mark; * 1 or2 correct 0 mark (b) | Asacontrol/ to measure background radiation only 1 (c)(i) Gamma radiation (allow symbol for gamma) 1 (c)(ii) Alpha and Beta radiation (allow answers in either order) (allow symbols) 2 (c)(iii) Alpha radiation (allow symbol) 1 (d) Any suitable safety procedure related to the use of radioactive materials 1 answer should indicate use of shield (lead), teacher not handling materials directly (i.e. use of tweezers etc), pupils/teacher as far from source as possible, not pointing source at anyone etc. do NOT allow vague references to use of protective clothing or goggles (e) __ Inside locked [1], lead-lined [1] safe (marks independent) 2 ignore references to radioactive warning signs

Page 3 Mark Scheme Syllabus | Paper | IGCSE Examinations — November 2002 0652 6 Marking Scheme Details Part Mark 3. (a) Mi = 38.2g [1] (no tolerance) M2 = 41.7g [1] (no tolerance) M3= 3.5g[1] (no tolerance) T1 = 25.5°C [1] (no tolerance) T2 = 16.8°C [1] (allow 16.75 to 16.85) 5 (b) Temperature charige = -8.7 °C (negative sign NOT required for mark) 1 allow ecf from Candidate’s answers for T; and T2 (c)G) Correct division by 1000 from candidate’s answer for M; i.e. 0.0382kg 1 (c)(Gi) Heat energy stored = 670 x (c)(i) = 25.594 joules (allow ecf from candidate’s answer to (€)(i)) (allow correct answer to 2 dp) 1 (d) Total heat change = 1136 J (allow ecf from candidate’s answers to (b) and 1 (Gd) (e) Endothermic because temperature falls (explanation required for mark) 1 (allow ‘endothermic because heat is lost’)

Page 4 Mark Scheme Syllabus Paper IGCSE Examinations — November 2002 0652 Q. No. Marking Scheme Details Part Mark 4. (a) Any THREE points from: Filter the juice [1] boil the filtrate [1] (allow heat the filtrate) to partly evaporate [1] leave to cool/crystallise [1] 3 (b) Any SEVEN points from: dissolve the weighed [1] crystals allow dissolve crystals in water for 1 mk in a measured volume of water [1] take a measured volume [1] and add indicator[1] add sodium hydroxide from a burette [1] record volume needed to change colour of indicator [1] repeat and average volume of sodium hydroxide required [1] repeat without the indicator using same volumes [1] evaporate solution [1] P allow to cool / crystallise [1] 7

Page 5 Mark Scheme Syliabus | Paper IGCSE Examinations — November 2002 0652 6 Q. No. Marking Scheme Details i Part Mark 5. (a) Correct symbo! for switch 1 (b) @) Switch drawn somewhere on the circuit between points A-B or C-D 1 (b) (ii) Switch drawn somewhere on the circuit between points A & D 1 (b) (iii) Switch drawn somewhere on the circuit between points A-F or D-E 1 Ecf from (a) — if incorrect / no symbol drawn allow correct positions to score but must be labeled as required ie. S1, $2, S3 (c) Correct symbol for voltmeter [1] Drawn in correct place parallel to battery [1] These marks independent of each other e.g. incorrect symbol in correct place still scores one mark and vice versa.

Page 6 Mark Scheme Syllabus | Paper IGCSE Examinations — November 2002 0652 6 Q. No. [ Marking Scheme Details 6. (a) Conclusion — (Gas was) carbon dioxide Liquid is sulphuric acid/A [1] / (COz) [1] (b) Conclusion — (the pH was) alkali(ne) [1] Liquid is calcium hydroxide/B [1] or greater than 7 or writes number 8 - 14 (©) wenn ; Liquid is (purified) water/C [1] (d) Conclusion —Precipitate was barium sulphate/ Liquid is sulphuric acid/A [1] a sulphate (SO,") (ions) [1] () —- Liquid is calcium hydroxide/B [1] Accept correct chemical formulae for answers above.

Page7 Mark Scheme Syllabus | Paper IGCSE Examinations — November 2002 0652 6 Marking Scheme Details Part Mark Indicates pencil/ruler used to draw line on paper [1] Teat pipettes used to put spots of M and all dyes on the paper [1], just above or on the line [1] Spots are separated by small distances [1] Paper is coiled (and held with paper clip) [1] / dipped into beaker containing water (‘solvent’ or named solvent e.g. ethanol)[1] (accept paper suspended in water using paper clip to hold it) Water/solvent level:is below pencil line [1] [6] Water/solvent is allowed to soak up paper to separate dyes [1] Spots / colours are compared to see which ones are present in M [1] ANY SIX points from the above indicated by description or clearly identified by diagrams. Clearly labelled and accurate diagrams may gain all marks with little explanation. The sequence should generally be in the above order but allow minor deviations as long as the experiment would work