Cambridge IGCSE Science - Combined 0653 — 2003 Oct/Nov Paper 6 · Variant 1

This document consists of 18 printed pages and 2 blank pages. SP (AT/SLC) S42208/3 © UCLES 2003 [Turn over CAMBRIDGE INTERNATIONAL EXAMINATIONS International General Certificate of Secondary Education COMBINED SCIENCE 0653/06, 0654/06 CO-ORDINATED SCIENCES Paper 6 Alternative to Practical Test October/November 2003 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 in the spaces provided on the Question Paper. You may use a soft pencil for any diagrams, graphs or rough working. Do not use staples, paper clips, highlighters, glue or correction fluid. 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. Centre Number Candidate Number Name If you have been given a label, look at the details. If any details are incorrect or missing, please fill in your correct details in the space given at the top of this page. Stick your personal label here, if provided. For Examiner’s Use 3 2 1 4 Total 6 5 www.XtremePapers.com

2 0654/6/O/N/03 1 A student did an experiment to find if alcohol has an effect on the rate of heartbeat of water fleas. The water fleas are so small that they have to be studied using a microscope. The heart can be seen easily in the place shown in Fig. 1.1. Fig. 1.1 • He placed a water flea onto a microscope slide and counted the number of heart beats in 15 seconds. • Using a pipette he removed the water surrounding the flea and replaced it with 1% alcohol. • He counted the new rate for 15 seconds. • He repeated this procedure with a different flea. • He then did the experiment with two more fleas in alcohol solutions of different concentrations shown in the table. • He multiplied each reading by four to give the heart rate per minute. • He recorded his results in the table, Fig. 1.2. Fig. 1.2 (a) Complete the table by calculating the average heart rate for each alcohol concentration. [2] eye heart brood pouch gut For Examiner’s Use first reading of second reading of average heart alcohol concentration / % heart rate / beats heart rate / beats rate / beats per per minute per minute minute 0 204 216 1 188 196 2 168 180 3 140 152 4 96 88 5 44 48 6 36 32 7 20 28 8 24 12

3 0654/6/O/N/03 (b) Plot a graph of average heart rate against alcohol concentration on the grid provided. [3] [Turn over alcohol concentration/% average heart rate/beats per minute For Examiner’s Use

4 0654/6/O/N/03 (c) Describe how alcohol affected the heart rate of the water fleas, (i) at alcohol concentration between 0% and 2%, … … (ii) at alcohol concentrations between 3% and 5%. … …[2] (d) The nervous system controls the heart rate in both fleas and humans. Suggest how drinking alcohol affects the speed of response of the human nervous system. … …[1] (e) (i) Suggest one possible source of error in the experiment. … … (ii) Suggest one way in which the experiment could be improved. … …[2]

5 0654/6/O/N/03 Question 2 can be found on page 6 For Examiner’s Use [Turn over

6 0654/6/O/N/03 2 Three students each set up an experiment using the apparatus shown in the diagram, Fig. 2.1. Fig. 2.1 • Each of the 100 cm3 flasks contained a small mass of one of the metals X, Y or Z with 5 cm3 of water. • At first, all the syringes were set at the 25 cm3 mark. • The flasks were left for one week. • The students recorded their results in the table, Fig. 2.3. (a) Fig. 2.2 shows the scales of the syringes after one week. Fig. 2.2 experiment 1 20 30 40 metal X + 5cm3 water experiment 3 40 50 metal Z + 5cm3 water experiment 2 0 10 metal Y + 5cm3 water graduated syringe flask powdered metal + 5cm3 water For Examiner’s Use

7 0654/6/O/N/03 Record the readings of the syringes in the table, Fig. 2.3. [3] Fig. 2.3 (b) Suggest the names of the metals used in the experiments 1–3. Choose from the following list of metals. (there may be more than one correct answer each time) calcium copper iron magnesium zinc Explain your answers. (i) Metal X could be … explanation … …[1] (ii) Metal Y could be … explanation … …[2] (iii) Metal Z could be … explanation … …[2] (c) Name the gas made by the reaction in experiment 3. …[1] For Examiner’s Use [Turn over experiment flask contained syringe reading on syringe reading after number day 1 / cm3 one week / cm3 1 metal X + 5 cm3 of water 25 2 metal Y + 5 cm3 of water 25 3 metal Z + 5 cm3 of water 25

8 0654/6/O/N/03 3 A student did an experiment to investigate the solubility of potassium nitrate in water at different temperatures. The student placed 7.0 g of potassium nitrate and 4.0 cm3 of water in a large test-tube. • He heated the test-tube in a water bath until all the crystals had dissolved. • He allowed the test-tube to cool and gently stirred the contents with the thermometer. • When he saw small shiny crystals in the solution, he recorded the temperature in the results table, Fig. 3.2. • He added 1.0 cm3 of water to the test-tube and stirred the mixture. Then the steps shown above were repeated to find another temperature at which crystals began to appear. He added 1.0 cm3 portions of water to the tube until the total volume of water was 12.0 cm3. Each time he found the temperature at which crystals began to appear. Fig. 3.1 shows the scale of the thermometer for three of the experiments. Fig. 3.1 50 60 70 80 experiment 2 50 60 70 80 experiment 3 50 60 70 80 experiment 4 For Examiner’s Use

9 0654/6/O/N/03 (a) Read the thermometers in Fig. 3.1 and record the results in the table, Fig. 3.2. [3] Fig. 3.2 (b) Complete Fig. 3.2 by calculating the missing value for the mass of potassium nitrate in 100 g water. [1] For Examiner’s Use [Turn over experiment total volume mass of mass of potassium number of water / cm3 potassium nitrate per 100 cm3 temperature / °C nitrate / g of water / g 1 4.0 7.0 175.0 78 2 5.0 7.0 3 6.0 7.0 117.0 4 7.0 7.0 100.0 5 8.0 7.0 87.5 50 6 12.0 7.0 58.3 38

10 0654/6/O/N/03 (c) On the graph grid provided, Fig. 3.3, plot a graph of mass of potassium nitrate per 100 g water (vertical axis) against temperature. Draw a smooth curve. [3] Fig. 3.3 For Examiner’s Use 0 20 40 60 80 100 120 140 160 180 0 10 20 30 40 50 60 70 80 mass of potassium nitrate per 100g water/g temperature/°C P

11 0654/6/O/N/03 (d) A point P has already been marked on the graph grid. Study the graph and then complete the following sentence about point P. The point P represents a solution of … g potassium nitrate in … g of water at a temperature of … °C. [1] (e) The student wants to get solid potassium nitrate from the solution. Explain carefully how he can do this. … … …[2] For Examiner’s Use [Turn over

12 0654/6/O/N/03 4 This question is about heat loss in animals. During cold weather some animals group together (huddle) to keep warm. A student did an experiment to find how effective such huddling is. She used test-tubes of hot water to represent the animals. • She half-filled eight test-tubes with hot water. • She used an elastic band to make a bundle of seven tubes with test-tube A surrounded by six other test-tubes. • She put a thermometer into test-tube A. • She also put a thermometer into the eighth test-tube, B, which she kept separate. • She then put the tubes in beakers as shown in the diagram, Fig. 4.1. • Then she took the initial temperature of the water in both test-tubes. She continued to take the temperature every minute for ten minutes. Fig. 4.1 (a) results for test-tube A initial temperature = 60 °C readings / °C 59 58 reading (i) 57 57 56 55 55 54 54 results for test-tube B initial temperature = 61 °C readings / °C 58 55 53 51 49 47 46 44 reading (ii) 42 elastic band water bundle of seven test-tubes beaker water in tube B tube A elastic band view of tubes from above For Examiner’s Use

13 0654/6/O/N/03 Read the thermometers (i) and (ii) in Fig. 4.2 below to complete the sets of results. Write your answers in the spaces provided. Fig. 4.2 (i) … °C (ii) … °C [2] (b) Construct a table showing times and temperatures to display all the results clearly. [2] 20 30 40 50 60 70 °C 0 10 20 30 40 50 °C For Examiner’s Use [Turn over

14 0654/6/O/N/03 (c) Which test-tube, A or B, took longer to cool down? …[1] (d) Is huddling effective? Use your results and your knowledge of heat transfer to explain your answer. … … … …[3] (e) Suggest two ways in which you could improve the accuracy of the experiment. … … …[2] For Examiner’s Use

15 0654/6/O/N/03 5 A student is given substance X, which is a mixture of a salt and a metal oxide. Substance X is a black solid. She does the following tests and writes her observations. (a) Complete the table, Fig. 5.1, by writing the conclusions. Fig. 5.1 (b) Suggest another test the student might use to confirm the presence of the gas from test 5. What result can she expect for your test? test … result …[2] For Examiner’s Use [Turn over test observation conclusion 1. To a small amount of X, add blue solution formed 5 cm3 dilute nitric acid and warm. [1] 2. Warm a portion of X with black residue in filter 15 cm3 water in a large paper and a colourless test-tube. Filter the mixture filtrate and use 2 cm3 of the filtrate for each of the tests 3–5. 3. To 2 cm3 of the filtrate from colourless solution, no test 2, 5 cm3 hydrochloric bubbling seen acid was added. [1] 4. To 2 cm3 of the filtrate from white precipitate test 2, a few drops of nitric acid were added, followed by silver nitrate solution. [1] 5. To 2 cm3 of the filtrate from pungent-smelling gas test 2, about 1 cm3 given off, turns red aqueous sodium hydroxide litmus blue was added. The mixture was warmed. [1] 6. About 10 cm3 warm dilute blue solution formed nitric acid was poured on to the residue from test 2. The filtrate was collected.

16 0654/6/O/N/03 (c) The student thinks that the filtrate from test 6 might contain copper ions. She tries adding ammonia solution to some of the filtrate. (i) What will she see when she adds a few drops of ammonia solution, if copper is present? … … (ii) What will she see when she adds an excess of ammonia solution, if copper is present? … …[3] (d) Suggest what substances are present in substance X. … and …[2] For Examiner’s Use

17 0654/6/O/N/03 6 Two students do an experiment to determine the speed of sound in air. The first student fires a gun at point X, 1000 metres away from the second student at point Y. Fig. 6.1 • A microphone on the gun picks up the sound. It sends a signal to a radio transmitter. This signal is sent to the radio receiver at point Y. The receiver sends input A to a cathode ray oscilloscope (c.r.o.). • A dish at point Y reflects the sound to a microphone in the dish. This sends input B to the c.r.o. • The sound of the gun travels through the air. When the second student hears the sound of the gun at point Y, he presses a switch to send input C to the c.r.o. (a) The inputs to the c.r.o. are pulses of energy. State how the energy travels from point X to point Y in each case. (i) input A … (ii) input B …[2] (b) Explain why the microphone at point Y needs a reflector dish but the microphone at point X does not need one. … …[1] radio transmitter radio receiver cathode ray oscilloscope point X point Y input C input A input B gun with microphone dish with microphone 1000 metres For Examiner’s Use [Turn over

18 0654/6/O/N/03 (c) The screen of the c.r.o. is saved and displayed. This is shown in Fig. 6.2. Fig. 6.2 The c.r.o. is set so that 1 cm on the horizontal axis = 0.5 seconds. Use the information in Fig. 6.2 to determine (i) the length of time, t1, between input A and input B, t1 = …s [1] (ii) the length of time, t2, between input A and input C, t2 = …s [1] 0 input A input B input C 1cm = 0.5s (horizontal axis) For Examiner’s Use

19 0654/6/O/N/03 (d) Calculate the speed of sound in metres per second as it travels from point X to point Y (i) using t1 from (c)(i), speed of sound = …m / s [1] (ii) using t2 from (c)(ii), speed of sound = …m / s [1] (e) Which result, (d)(i) or (d)(ii), for the speed of sound is more reliable? Explain your answer. … …[2] (f) How can all of the results from this experiment be made more reliable? … …[1] For Examiner’s Use