Cambridge IGCSE Sciences - Co-ordinated (Double) 0654 — 2024 May/June Paper 5 · Variant 1

1 You are provided with a slice of a citrus fruit. (a) In the box, make a large, detailed, pencil drawing of the slice of fruit. [3] (b) (i) Record the diameter of the slice of fruit in millimetres. diameter of the slice of fruit = .................................................. mm [1] (ii) Draw a line to show the diameter of the slice of fruit on your drawing in (a). Record the length of this line in millimetres. diameter of the slice of fruit on drawing = .................................................. mm [1] (iii) Calculate the magnification m of your drawing. Use your measurements in (b)(i) and (b)(ii) and the equation shown. diameter of the slice of fruit on drawing m = diameter of the slice of fruit Record your value to two significant figures. magnification m = ......................................................... [2] (c) Fig. 1.1 is a photograph of a slice of a kiwi fruit shown actual size. Fig. 1.1 State two visible differences between the slice of citrus fruit and the slice of kiwi fruit shown in Fig. 1.1. difference 1 ............................................................................................................................... ................................................................................................................................................... difference 2 ............................................................................................................................... ................................................................................................................................................... [2] [Total: 9]

Mark scheme: 1(a) quality – clear and continuous lines ; size – circular and at least half the box used and must fit inside the box ; detail – skin and minimum 6 segments ; 3 1(b)(i) measurement in mm ; 1 1(b)(ii) line drawn and measurement ; 1 1(b)(iii) correct calculation ; 2 SF ; 2 1(c) any two from: size / orange is larger / kiwi is smaller ; shape / orange is round and kiwi is oval ; seeds / presence of seeds / number of seeds / orange has fewer/no seeds / kiwi has (more) seeds ; skin / orange has thicker skin / kiwi has thinner skin ; segments / orange has segments / kiwi doesn’t have segments ; core / orange has larger core / kiwi has smaller core / kiwi has flesh in the centre ; 2

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2 You are going to compare the vitamin C concentration of orange juice with other fruit juices. DCPIP is a blue solution that decolourises (goes colourless) when vitamin C is added to it. DCPIP is used as an indicator for vitamin C concentration as shown in Fig. 2.1. few drops of vitamin C needed to high vitamin C concentration decolourise DCPIP many drops of vitamin C needed to low vitamin C concentration decolourise DCPIP Fig. 2.1 You are provided with samples of orange juice and three other fruit juices, D, E and F. (a) Read through the procedure in (b). Draw a table to record your results. [2] (b) Procedure • Use a dropping pipette to place two drops of DCPIP into a clean well of the white spotting tile. • Use a clean dropping pipette to add drops of orange juice into the well containing DCPIP. • Count how many drops are needed to decolourise DCPIP and record the result in your table. If the DCPIP does not decolourise, stop when the well is full. Record the number of drops and add “full” next to the number. Repeat the procedure with juice D, juice E and juice F, instead of orange juice. [4] (c) Use your results table and Fig. 2.1 to place the juices in order of their vitamin C concentration. highest vitamin C ............................................... ............................................... ............................................... lowest vitamin C ............................................... [2] (d) Counting the number of drops is one source of error in this procedure. Explain why this is a source of error and suggest one improvement. explanation ............................................................................................................................... ................................................................................................................................................... improvement ............................................................................................................................. ................................................................................................................................................... [2] (e) Scurvy is a disease caused by a lack of vitamin C in the diet. A student does not drink orange juice or fruit juices D, E and F. Suggest why the student does not get scurvy. ................................................................................................................................................... ............................................................................................................................................. [1] [Total: 11]

Mark scheme: 2(a) headings juice / number of drops separated ; juice labels and results separated ; 2 2(b) set of results for orange ; the other three results ; fruit with most drops matches supervisor ; fruit with least drops matches supervisor ; 4 2(c) all 4 are placed in ranked order ; one with most vit C (fewest drops) at the top ; 2 2(d) drop size varies / losing count ; measure volume / do on a larger scale ; 2 2(e) other sources in diet ; 1

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3 You are going to investigate the reaction between magnesium and aqueous copper sulfate. More reactive metals displace less reactive metals from solutions of their salts. magnesium + copper sulfate magnesium sulfate + copper The unit M is used to measure the concentration of a solution. The higher the value of M, the more concentrated the solution. A 1 M solution is two times more concentrated than a 0.5 M solution. (a) (i) Procedure • Place the polystyrene cup in the empty beaker. • Use the measuring cylinder to add 25 cm3 of 1.00 M aqueous copper sulfate to the polystyrene cup as shown in Fig. 3.1. polystyrene cup aqueous copper sulfate beaker Fig. 3.1 • Record in Table 3.1 the initial temperature of the aqueous copper sulfate in the cup to the nearest 0.5 °C. • Add one spatula load of magnesium powder to the aqueous copper sulfate in the cup. • Stir the mixture and record in Table 3.1 the highest temperature reached to the nearest 0.5 °C. • Place the reaction mixture into the container labelled waste. • Rinse the cup with water to remove all the reaction mixture. Pour this rinsing water into the waste container. Repeat the procedure using the concentrations of aqueous copper sulfate shown in Table 3.1. Table 3.1 concentration initial temperature highest temperature of temperature increase of aqueous of aqueous the mixture ΔTcopper sulfate copper sulfate / °C / °C / M / °C 1.00 0.75 0.50 0.25 0.00 21.5 21.5 0.0 [4] (ii) Look at the mixture in the waste container. State the colour of the solid. Suggest the identity of this solid. colour ................................................................................................................................ identity ............................................................................................................................... [2] (iii) Explain why the polystyrene cup is placed in the beaker. ........................................................................................................................................... ..................................................................................................................................... [1] (b) (i) Calculate the temperature increase ΔT for each concentration. The results for 0.00 M aqueous copper sulfate are already in Table 3.1. Record these values in Table 3.1. [1] (ii) On the grid, plot a graph of temperature increase ΔT (vertical axis) against concentration of aqueous copper sulfate. [3] (iii) Draw the best-fit straight line. [1] (iv) A teacher says that the temperature increase is proportional to the concentration of aqueous copper sulfate. Suggest if this is supported by your data. Explain your answer. ........................................................................................................................................... ..................................................................................................................................... [1] (v) Use your graph to estimate the temperature increase ΔT when 0.35 M aqueous copper sulfate is used in this procedure. ΔT = ..................................................... °C [1] (vi) Suggest one improvement to the procedure which will give more confidence in the values of ΔT. Do not include repeating the procedure. Explain your answer. improvement ..................................................................................................................... ........................................................................................................................................... explanation ........................................................................................................................ ........................................................................................................................................... [1] [Total: 15]

Mark scheme: 3(a)(i) initial T copper sulfate and highest T both recorded ; other 3 sets of values recorded ; all recorded to 0.5 °C ; T decreasing down table ; 4 3(a)(ii) brown / orange / pink ; copper ; 2 Question Answer Marks 3(a)(iii) for stability ; 1 3(b)(i) all T values correct ; 1 3(b)(ii) axes correct orientation and labelled with quantity and unit ; sensible linear scales with plotted points covering ⩾ ½ grid and all points able to be plotted ; points plotted correctly  ½ small square ; 3 3(b)(iii) best fit straight line through origin ; 1 3(b)(iv) statement according to results and graph used to justify ; 1 3(b)(v) value from graph ; 1 3(b)(vi) any one from: insulate / use lid AND less heat loss ; find the mass of magnesium AND so only variable is copper sulfate concentration / so mass is controlled ; 1

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4 You are going to identify the ions in solution H. (a) Procedure • Add approximately 2 cm depth of solution H into each of five clean test-tubes. • Soak a wooden splint in one test-tube and leave for the last test in Table 4.1. • Do the tests in Table 4.1 on separate test-tubes of solution H and record your observations. Table 4.1 test observation add approximately 3 cm depth of aqueous ammonia add approximately 3 cm depth of aqueous sodium hydroxide add approximately 1 cm depth of dilute nitric acid and approximately 1 cm depth of barium nitrate add approximately 1 cm depth of dilute nitric acid and a few drops of aqueous silver nitrate place the wooden splint into the top of a blue Bunsen burner flame note the initial colour, if you do not see a colour repeat the test [3] (b) Identify the ions present in solution H. ................................................................................................................................................... ............................................................................................................................................. [2] [Total: 5]

Mark scheme: 4(a) colourless solution / no reaction / no precipitate/ppt and colourless solution / no reaction / no precipitate/ppt and colourless solution / no reaction / no precipitate/ppt ; white precipitate / ppt ; lilac ; Question Answer Marks 4(b) potassium / K+ ; chloride / Cl– ; 2

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5 You are going to investigate how the resistance R of a lamp changes as the current I flowing through the lamp changes. Fig. 5.1 shows a circuit using a lamp. The circuit is assembled for you. V A l S P Q resistance wire metre rule Fig. 5.1 (a) Procedure • Close the switch. • Place the sliding contact S on the resistance wire at a distance l = 20.0 cm from end P. • Record in Table 5.1 the current I in the lamp and the potential difference V across the lamp. • Open the switch. Table 5.1 length of resistance current I potential difference V resistance R wire l / cm / A / V / Ω 20.0 40.0 60.0 80.0 [2] (b) Repeat the procedure in (a) for values of l = 40.0 cm, 60.0 cm and 80.0 cm. [3] (c) Suggest why it is important to open the switch after taking each pair of readings of the current I and the potential difference V. ................................................................................................................................................... ............................................................................................................................................. [1] (d) Calculate the resistance R of the lamp for each length of wire. Use the equation shown. V R = I Record your values of R in Table 5.1. [2] (e) (i) Describe how the resistance R of the lamp changes as the length l of resistance wire changes. ..................................................................................................................................... [1] (ii) Describe how the resistance R of the lamp changes as the current I flowing through the lamp changes. ..................................................................................................................................... [1] (f) A student suggests that the resistance R of the lamp is proportional to the potential difference V across it. State if the values of R and V in Table 5.1 support the student’s suggestion. Use values from Table 5.1 to explain your answer. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ............................................................................................................................................. [2] (g) A student finds that when the length l of the resistance wire is greater than 80.0 cm, the lamp does not glow. Suggest how the student checks that the lamp is not broken. ................................................................................................................................................... ............................................................................................................................................. [1] [Total: 13]

Mark scheme: 5(a) V value recorded ; I value recorded ; 2 5(b) rest of values recorded ; all V values < 3 V and to at least 1 d.p. ; all I values < 1 A and to at least 2 d.p. ; 3 5(c) so that the cell does not run down / wire does not overheat ; 1 5(d) all R values recorded ; all values correct ; 2 5(e)(i) R decreases as l increases / or reverse ; 1 5(e)(ii) R decreases as I decreases / or reverse ; 1 5(f) Expect no and R / V is not constant / equivalent ; table values used to confirm statement ; 2 5(g) check that the ammeter gives a reading / go back/do a lower length (and check a previous reading / see if it glows) ; 1

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6 A student investigates the cooling of hot water in a beaker. Plan an experiment to investigate the relationship between the thickness of the cardboard insulation wrapped around a beaker and the rate of cooling of hot water in the beaker. You are provided with: • a supply of hot water • a beaker • a measuring cylinder • thin sheets of cardboard. You may use any other common laboratory apparatus. You are not required to do this investigation. In your plan include: • any other apparatus needed • a brief description of the method, including what you will measure and how you will make sure your measurements are accurate • the variables you will control • a results table to record your measurements (you are not required to enter any readings in the table) • how you will process your results to draw a conclusion. You may include a labelled diagram if you wish. .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .................................................................................................................................................... [7] NOTES FOR USE IN QUALITATIVE ANALYSIS Tests for anions anion test test result carbonate (CO32–) add dilute acid effervescence, carbon dioxide produced chloride (Cl –) acidify with dilute nitric acid, then white ppt. [in solution] add aqueous silver nitrate bromide (Br –) acidify with dilute nitric acid, then cream ppt. [in solution] add aqueous silver nitrate nitrate (NO3–) add aqueous sodium hydroxide, then ammonia produced [in solution] aluminium foil; warm carefully sulfate (SO42–) acidify, then add aqueous barium white ppt. [in solution] nitrate Tests for aqueous cations cation effect of aqueous sodium hydroxide effect of aqueous ammonia ammonium (NH4+) ammonia produced on warming – calcium (Ca2+) white ppt., insoluble in excess no ppt., or very slight white ppt. 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 white ppt., soluble in excess, giving a colourless solution colourless solution Tests for gases Flame tests for metal ions gas test and test result metal ion flame colour ammonia (NH3) turns damp red litmus paper blue lithium (Li+) red carbon dioxide (CO2) turns limewater milky sodium (Na+) yellow chlorine (Cl 2) bleaches damp litmus paper potassium (K+) lilac hydrogen (H2) ‘pops’ with a lighted splint copper(II) (Cu2+) blue-green oxygen (O2) relights a glowing splint

Mark scheme: 6 One mark from each section and any two others additional apparatus: stop-watch and its use ; thermometer and its use ; ruler and its use ; method: wrap cardboard round beaker and add hot water and measure a temperature for at least 2 thicknesses of cardboard ; measurement and table measure the thickness of the cardboard ; measure initial temperature of water ; measure the time for a specific temperature decrease / (final) temperature in a specific time ; repeat for 5 different thicknesses of cardboard ; repeat for each thickness and remove / identify anomalies ; table columns thickness / sheets (of insulation) and temperature/time ; control variables: mass / volume / amount of hot water ; same initial hot-water temperature ; same room temperature ; same size / thickness / material of beaker ; processing and conclusion: calculates rate of cooling by taking temp change ÷ time ; graph with rate vs number sheets / thickness ; see if increasing thickness increases or decreases the rate of cooling / describe relationship from shape of graph ; 7

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