Cambridge IGCSE Sciences - Co-ordinated (Double) 0654 — 2025 Oct/Nov Paper 5 · Variant 2

1 You are going to test potato and milk for their nutrient content. (a) Read through the procedure in (a)(ii). (i) Draw a table to record your results from (a)(ii). [2] (ii) Procedure step 1 Cut the cube of potato into two pieces. step 2 Place one piece of potato into each of two test‑tubes. step 3 Add about 2 cm depth of biuret solution to one of these test‑tubes. step 4 Add a few drops of iodine solution to the other test‑tube. step 5 Add about 2 cm depth of milk to each of two clean test‑tubes. step 6 Repeat steps 3 and 4 with the milk instead of the potato pieces. Record in your results table in (a)(i) the final colours observed in each test‑tube. [4] (iii) Use your results to state the nutrients that the potato and milk contain. potato contains .................................................................................................................. milk contains ..................................................................................................................... [2] (b) A student tests 10 cm3 of two fruit juices, A and B, with Benedict's solution. Both juices produce a precipitate. (i) State the name of the nutrient identified by Benedict's solution. ..................................................................................................................................... [1] (ii) Suggest a suitable temperature the student uses for the test. temperature = ................................................... °C [1] (iii) Method 1 The precipitates produced in the tests in (b) are filtered, dried and weighed. The greater the mass of precipitate, the more nutrient the fruit juice contains. The student repeats the experiment two more times. Table 1.1 shows the masses the student obtains. Table 1.1 mass of precipitate / g fruit juice trial 1 trial 2 trial 3 average A 0.55 0.59 0.58 B 0.81 0.86 0.87 Calculate the average mass for each juice. Record in Table 1.1 your values to two significant figures. [2] (iv) Method 2 The student repeats the tests in (b) using the same volumes of fruit juice and Benedict’s solution. The student observes and records the colour of the solution formed. The student repeats the experiment two more times. Benedict’s solution gives a range of colours to indicate how much of the nutrient is present. Explain why method 1 allows the student to have more confidence in determining how much of the nutrient is present in each fruit juice. ........................................................................................................................................... ........................................................................................................................................... ..................................................................................................................................... [1] (v) Suggest why the Benedict’s solution needs to be in excess in method 1. ........................................................................................................................................... ..................................................................................................................................... [1] [Total: 14]

Mark scheme: Question Answer Marks 1(a)(i) headings for potato and milk ; 2 headings for biuret and iodine (final colours) ; 1(a)(ii) 4 final colour final colour biuret iodine potato blue ; blue-black ; milk purple ; brown ; 1(a)(iii) potato contains) starch ; 2 (milk contains) protein ; 1(b)(i) reducing sugar ; 1 1(b)(ii) temperature > 40 and < 100 ; 1 1(b)(iii) 0.57 ; 2 0.85 ; 1(b)(iv) (method 1), is not subjective / is quantitative 1 OR method 2, is subjective / qualitative ; 1(b)(v) to react all of the nutrient ; 1

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2 You are provided with a leaf. (a) In the box make a large, detailed pencil drawing of the leaf. [3] (b) Fig. 2.1 shows photographs of leaves, C and D, from two different trees. The photographs are at the same magnification. leaf C leaf D Fig. 2.1 State one similarity and two differences between leaf C and leaf D visible in Fig. 2.1. similarity .................................................................................................................................... ................................................................................................................................................... difference 1 ............................................................................................................................... ................................................................................................................................................... difference 2 ............................................................................................................................... ................................................................................................................................................... [3] [Total: 6]

Mark scheme: 2(a) quality – clear and continuous outline and pointy edges ; 3 size –at least half the box used and must fit inside the box ; detail – 3 lobes and central vein in each lobe and a few smaller veins ; 2(b) similarity 3 (both have), veins / midribs / vascular bundle(s) / xylem / phloem / vein along the middle ; difference any two from: shape • C has lobes / D has one / no lobes ; • C is spikey or irregular or serrated or zig zag / D is smooth or regular ; • D is oval shaped / D is curved / D is rounded / C is not oval shaped / C is not curved / C is not rounded ; size • leaf C is large(r) / leaf D is small(er) / leaf C is wide(r) / leaf D is narrow(er) ; leaf stalk • C has a leaf stalk / D has no leaf stalk ;

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3 You are going to investigate the effect of concentration on the rate of a reaction. Copper carbonate reacts with dilute hydrochloric acid forming carbon dioxide gas. Copper carbonate does not dissolve in or react with water. An aqueous solution is made less concentrated by adding water to it. (a) Procedure • Use a measuring cylinder to add 5 cm3 of dilute hydrochloric acid to a conical flask. • Use a clean measuring cylinder to add 20 cm3 of water to the conical flask. • Add 2 spatula loads of copper carbonate to the conical flask. • Swirl the flask and immediately start a stop‑watch. • Stop the stop‑watch when the reaction finishes. • Record in Table 3.1 the time taken to the nearest second for the reaction to finish. This is the reaction time. Repeat the procedure using the volumes shown in Table 3.1. Table 3.1 volume of dilute volume of water reaction time hydrochloric acid / cm3 / s / cm3 5 20 10 15 15 10 20 5 25 0 [4] (b) (i) Explain how you know when the reaction has finished. ........................................................................................................................................... ..................................................................................................................................... [1] (ii) Suggest why this experiment is not done using 0 cm3 of dilute hydrochloric acid, 25 cm3 of water and 2 spatula loads of copper carbonate. ........................................................................................................................................... ..................................................................................................................................... [1] (c) The volume of dilute hydrochloric acid is used to represent the concentration of the dilute hydrochloric acid. (i) On the grid, plot reaction time (vertical axis) against volume of dilute hydrochloric acid. [3] (ii) Draw the line of best fit. [1] (iii) State the relationship between the concentration of dilute hydrochloric acid and the rate of the reaction. ........................................................................................................................................... ..................................................................................................................................... [1] (iv) Use your graph to predict the reaction time when 12 cm3 of dilute hydrochloric acid are used. reaction time = ...................................................... s [1] (d) (i) Increasing the temperature of a reaction increases the rate of a reaction. On the grid in (c)(i), draw a line to show the expected results when the investigation is done at a higher temperature. Label this line H. [1] (ii) When the temperature increases the particles move faster. A reaction happens when the particles collide. Suggest why the reaction happens faster when the temperature is increased. ........................................................................................................................................... ..................................................................................................................................... [1] (e) It is possible to collect and measure the volume of carbon dioxide gas given off in the reaction. Name the one piece of apparatus used to collect and measure the volume of carbon dioxide gas. ............................................................................................................................................. [1] [Total: 15]

Mark scheme: 3(a) time for 5 cm3 HCl ; 4 time for all : time decreases down table ; all to nearest second ; 3(b)(i) stops bubbling ; 1 3(b)(ii) copper carbonate doesn’t react with water / there is no reaction ; 1 3(c)(i) axes correct orientation and labelled with quantity and unit ; 3 sensible linear scales where plotted points cover ≥ ½ the grid and all points can be plotted ; plotted points correct to ½ small square ; 3(c)(ii) best fit straight line from the plotted points ; 1 3(c)(iiii) as concentration increases rate increases ; 1 3(c)(iv) time read from graph correctly ; 1 3(d)(i) line lower than plotted line ; 1 3d(ii) more successful collisions / more frequent collisions ; 1 3(e) (gas) syringe ; 1

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4 You are going to identify some ions. You are given two solutions, aqueous X and aqueous Y. Only one of these solutions contains the sulfate ion. (a) Procedure • Put approximately 2 cm depth of aqueous X into a test‑tube. • Put approximately 2 cm depth of aqueous Y into a test‑tube. • Add a wooden splint to each test‑tube and leave the splints soaking for use in (c). • Put approximately 2 cm depth of aqueous X into a clean test‑tube. • Put approximately 2 cm depth of aqueous Y into a clean test‑tube. • Add a few drops of aqueous barium nitrate to these two test‑tubes. • Record in Table 4.1 your observations. Table 4.1 solution observations with aqueous barium nitrate X Y [1] (b) Suggest an improvement to the test which will identify the solution that contains the sulfate ion. Explain your answer. (You do not need to do this improved experiment.) improvement ............................................................................................................................. ................................................................................................................................................... explanation ............................................................................................................................... ................................................................................................................................................... [2] (c) Aqueous X and aqueous Y each contain the same cation. Procedure • Use the wooden splint that has been soaking in aqueous X. • Put the splint into the top of a blue Bunsen burner flame. • Observe the first colour seen and record this in Table 4.2. • If you do not see a colour repeat the test. Repeat the procedure with the splint from aqueous Y. Table 4.2 solution colour of flame X Y Identify the cation present in aqueous X and aqueous Y. ............................................................................................................................................. [2] [Total: 5]

Mark scheme: 4(a) white ppt and white ppt ; 1 4(b) add dilute (nitric) acid ; 2 breaks down carbonate ions ; 4(c) lilac for at least one flame colour ; 2 lilac for both flame colours and potassium ion ;

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5 You are going to calculate the focal length f of a converging lens. The apparatus shown in Fig. 5.1 has been assembled for you. illuminated object screen converging lens in holder lamp 0 100 u v metre ruler p Fig. 5.1 (a) (i) Procedure • Place the lens at a distance u = 30.0 cm from the illuminated object. • Switch on the lamp. • Move the screen backwards and forwards until there is a focused, sharp image on the screen. • Record the distance p of the screen from the illuminated object in cm to the nearest 0.1 cm. p = ......................................................... cm Calculate the distance v between the centre of the lens and the screen. Use the equation shown. v = p – 30.0 Record in Table 5.1 this distance v in cm to the nearest 0.1 cm. [2] Table 5.1 u / cm v / cm u × v u + v / cm f / cm 30.0 50.0 (ii) Repeat the procedure in (a)(i) using a distance u = 50.0 cm between the illuminated object and the lens. p = ......................................................... cm Calculate the distance v between the centre of the lens and the screen. Use the equation shown. v = p – 50.0 Record in Table 5.1 this distance v in cm to the nearest 0.1 cm. [1] (iii) Repeat the procedure in (a)(i) using a distance u = 40.0 cm between the illuminated object and the lens. p = ......................................................... cm Calculate the distance v between the centre of the lens and the screen. Use the equation shown. v = p – 40.0 Record this distance in cm to the nearest 0.1 cm. v = ................................................... cm [1] (iv) Describe the relationship between u and v. Use the values of u and your values of v from Table 5.1 and (a)(iii). ........................................................................................................................................... ..................................................................................................................................... [1] (v) State one difficulty you have when following the procedure. Describe how this difficulty is overcome. difficulty ............................................................................................................................. ........................................................................................................................................... how to overcome ............................................................................................................... ........................................................................................................................................... [1] (b) (i) Calculate u × v for both values of u given in Table 5.1. Record these values in Table 5.1. [1] (ii) State the unit for u × v. .................................. [1] (iii) Calculate u + v for both values of u given in Table 5.1. Record these values in Table 5.1. [1] (iv) Calculate f for both values of u given in Table 5.1. Use the equation shown. u × v f = u + v Record these values in Table 5.1. [2] (c) Two students do another experiment to determine the focal length f of a different lens. The lens has a focal length f of 10.6 cm. The students each determine a value for f and repeat the experiment three more times. Their values for f are shown in Table 5.2. Table 5.2 f / cm trial 1 trial 2 trial 3 trial 4 student A 10.7 10.2 12.3 10.1 student B 10.6 10.4 10.6 10.5 The results for student B are more accurate than the results for student A. Use the data in Table 5.2 to explain why the results for student B are more accurate. ................................................................................................................................................... ............................................................................................................................................. [1] (d) The students use an identical ruler to measure the height of an image on a screen. The students each take a single measurement of the height. The students record their results in mm as shown. student A, height of image = 21.2 mm student B, height of image = 21 mm The result from student A is not correct. Explain why. ................................................................................................................................................... ............................................................................................................................................. [1] [Total: 13]

Mark scheme: 5(a)(i) value of p present ; 2 v in table to 0.1 cm ; 5(a)(ii) value of v lower than the value for v in 5(a)(i) ; 1 5(a)(iii) value of v between v in 5(a)(i) and 5(a)(ii) ; 1 5(a)(iv) as u increases, v decreases / ORA ; 1 5(a)(v) suitable difficulty AND how to overcome it ; 1 e.g. • lights were too bright – close the blinds ; • difficulty in getting clear focused image – move screen slowly / back and forth ; 5(b)(i) both uv correct ; 1 5(b)(ii) cm2 ; 1 5(b)(iii) both u + v correct ; 1 5(b)(iv) both f correct ; 2 both f within 13.5 – 16.5 cm ; 5(c) B are closer to the true value / ORA ; 1 5(d) will not measure to 0.1 mm ; 1

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6 A student investigates the time taken for one swing of a pendulum (period). Plan an experiment to determine the relationship between the time for one swing of a pendulum (period) and the length of the string, l. You are provided with the assembled apparatus shown in Fig. 6.1. clamp string l stand pendulum bob Fig. 6.1 You may use any common laboratory apparatus in your plan. You are not required to do this investigation. In your plan, include: • any additional apparatus • what you will measure including how you make sure your results are accurate • the variables you will control • a results table to record your measurements (you are not required to enter any readings into the table) • how you will process your results to form a conclusion. .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .................................................................................................................................................... [7]

Mark scheme: 6 one from each section and any two others: 7 apparatus ruler and used in the method ; timer and used in the method ; table headings: length, time ; both correct units present in the heading ; measurements at least 5 lengths ; repeat each length to identify anomalies / repeat each length to exclude anomalies ; use of a fiducial aid explained ; control variables angle of swing ; no draughts ; let go / do not push ; size of bob / mass of the bob / same bob ; number of swings provided more than one ; processing conclusion if multiple swings in their method - divide time by number of swings to find time for one swing ; plot graph of time against length ; describe shape of graph e.g. positive gradient – if time increases as length increases then positive relationship AND if time decreases as length increases then negative relationship ; when the length increases does the time for one swing increase or decrease (or stay the same) ;

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