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

1 (a) You are provided with a flower. Remove petals from one side of the flower to leave two petals on the flower. (i) In the box, make a large, detailed pencil drawing of the flower. Include the internal parts of the flower. [3] (ii) On your drawing, add a line labelled S to identify a stigma. [1] (b) (i) Draw a line on your drawing to show the width of one petal. Measure the width of this petal. Record this width in millimetres to the nearest millimetre. width of petal on drawing = .................................................. mm [1] (ii) Measure the same width of the petal on the actual flower. Record this width in millimetres to the nearest millimetre. width of petal on actual flower = .................................................. mm [1] (iii) Use your measurements in (b)(i) and (b)(ii) to calculate the magnification M of your drawing. Use the equation shown. width of petal on drawing M = width of petal on actual flower Give your answer to two significant figures. M = ......................................................... [2] (iv) A teacher states that the width of the petal in (b)(ii) does not represent the width of all of the petals on the flower. Suggest how to improve confidence in the value of the width of all the petals on the flower. ........................................................................................................................................... ..................................................................................................................................... [1] (c) A student investigates the elements present in a dried plant sample, a sample where all of the water has been removed from the plant. The student burns the dried plant sample in oxygen. The student tests the products formed. The gas product formed turns limewater milky. The liquid product formed turns white anhydrous copper sulfate blue. Name the two products identified by these tests. ...................................................................... and ..................................................................... State which elements these tests confirm are present in the dried plant sample. ................................................................................................................................................... [2] [Total: 11]

Mark scheme: Question Answer Marks 1(a)(i) quality – clear and continuous outline ; 3 size – at least half of the box and all drawing in the box ; detail – petals and carpel and stamen ; 1(a)(ii) stigma correctly labelled ; 1 1(b)(i) line drawn and measurement correct in mm ; 1 1(b)(ii) measurement correct ; 1 1(b)(iii) correct calculation ; 2 to 2SF ; 1(b)(iv) take more readings (of width) from different petals and calculate an average ; 1 1(c) carbon dioxide and water ; 2 carbon and hydrogen ;

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2 You are going to investigate the nutrient content of two solutions, A and B, made from two different parts of a flower. You are provided with: • 3 samples of solution A, labelled A1, A2 and A3 • 3 samples of solution B, labelled B1, B2 and B3. (a) Read all of the procedure in (b). Draw a results table to record the final colours observed for each solution. [2] (b) Procedure • Add about 1 cm depth of Benedict’s solution to test-tubes A1 and B1. • Place both of these test-tubes in the hot water-bath for at least 3 minutes. Continue with the procedure while you are waiting. • Add about 1 cm depth of biuret solution to test-tubes A2 and B2. • Add a few drops of iodine solution to test-tubes A3 and B3. (i) Record in your results table the final colours observed. [4] (ii) Use your results to reach conclusions about the nutrient content of solutions A and B. solution A .......................................................................................................................... ........................................................................................................................................... solution B .......................................................................................................................... ........................................................................................................................................... [3] [Total: 9]

Mark scheme: 2(a) one column / row headings for reagents ; 2 column / row headings for observations / (final) colours for solutions A and B ; 2(b)(i) A – yellow / green / orange / red for Benedict’s ; 4 B – purple for biuret ; A biuret and B Benedict’s blue ; A and B both brown with iodine ; 2(b)(ii) A contains reducing sugar ; 3 B contains protein ; neither contain starch ;

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3 You are going to investigate how the solubility of potassium sulfate changes with the volume of water in which it is dissolved. (a) Procedure step 1 Use a measuring cylinder to place 20 cm3 of distilled water into a conical flask. step 2 Add one spatula load of potassium sulfate to the water and stir. step 3 Keep adding potassium sulfate one spatula load at a time while stirring until no more dissolves. step 4 Record in Table 3.1 the number of spatula loads of potassium sulfate dissolved. step 5 Add 20 cm3 of distilled water to the conical flask. There is now a total of 40 cm3 of water in the conical flask. step 6 Add potassium sulfate one spatula load at a time while stirring until no more dissolves. step 7 Record in Table 3.1 the total number of spatula loads of potassium sulfate dissolved in the water. Remember this is the number recorded in step 4 added to the additional spatula loads in step 6. step 8 Add 20 cm3 of distilled water to the conical flask. step 9 Add potassium sulfate one spatula load at a time while stirring until no more dissolves. step 10 Record in Table 3.1 the total number of spatula loads of potassium sulfate dissolved in the water. step 11 Repeat step 8 to step 10 until 100 cm3 of water is in the conical flask. Table 3.1 total number of spatula total volume of water loads of potassium sulfate / cm3 dissolved 20 40 60 80 100 [3] (b) (i) On the grid, plot the total number of spatula loads of potassium sulfate dissolved (vertical axis) against total volume of water. [3] (ii) Draw the straight line of best fit. [1] (iii) Describe the relationship between the total volume of water and the total number of spatula loads of potassium sulfate dissolved. ........................................................................................................................................... ..................................................................................................................................... [1] (iv) Estimate how many spatula loads of potassium sulfate dissolve in 45 cm3 of water. Show on your graph how you determine your value. number of spatula loads of potassium sulfate = ....................................... [2] (c) Solubility of a solid is sometimes measured by how much solid dissolves in 1000 cm3 of water at a particular temperature. Calculate the solubility of potassium sulfate in this investigation. solubility = ....................................... spatula loads / 1000 cm3 of water [1] (d) Suggest two improvements to the method that increase the accuracy of the measurements. Do not include any form of temperature measurement. improvement 1 .......................................................................................................................... ................................................................................................................................................... improvement 2 .......................................................................................................................... ................................................................................................................................................... [2] [Total: 13]

Mark scheme: 3(a) number of spatula loads in 20 cm3 ; 3 full set of values ; values increasing ; 3(b)(i) axes correct way round and labelled with quantity and unit ; 3 sensible linear scales with points covering ⩾ ½ grid and all points can be plotted ; points plotted correctly  ½ small square ; 3(b)(ii) best-fit straight line ; 1 3(b)(iii) as volume (of water) increases number of spatulas (of K2SO4) increases ; 1 3(b)(iv) correct value from graph ; 2 2 lines drawn one from each axis to line ± ½ small square ; 3(c) value calculated correctly ; 1 3(d) use a graduated/volumetric pipette / burette for volume of water ; 2 use mass of potassium sulfate ;

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4 You are going to investigate copper sulfate. (a) (i) Procedure • Use a measuring cylinder to add 10 cm3 of water to a boiling tube. • Record in Table 4.1 the temperature of the water to the nearest 0.5 °C. • Add 2 spatula loads of anhydrous copper sulfate to the water. • Stir until all of the copper sulfate dissolves. • Record in Table 4.1 the highest temperature reached by the solution to the nearest 0.5 °C. • Keep this solution to use in (b)(i). Table 4.1 temperature of water / °C highest temperature of solution / °C increase in temperature ΔT / °C [3] (ii) Calculate the increase in temperature. Record your answer in Table 4.1. Calculate the thermal energy given out by the anhydrous copper sulfate as it dissolves. Use the equation shown. ΔE = 42 × ΔT ΔE = ....................................................... J [1] (b) (i) Pour 2 cm depth of aqueous copper sulfate from (a)(i) into a boiling tube. Add aqueous L dropwise to the aqueous copper sulfate, until in excess. Describe your observations. ........................................................................................................................................... ........................................................................................................................................... ..................................................................................................................................... [2] (ii) State the identity of aqueous L. ..................................................................................................................................... [1] [Total: 7]

Mark scheme: 4(a)(i) 2 temperatures ; 3 both temperatures to nearest 0.5° ; solution higher temperature ; 4(a)(ii) T and E calculated ; 1 4(b)(i) (pale) blue ppt ; 2 deep blue solution ; 4(b)(ii) (aqueous) ammonia ; 1

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5 When a metal ball drops into sand, it will form a small crater (hole). You are going to investigate how the diameter of the crater depends on the height from which the metal ball is dropped. (a) The equipment in Fig. 5.1 has been set up for you. metre ruler tray of base of dry sand retort stand Fig. 5.1 Procedure • Make the surface of the sand level using the small piece of wood. • Make sure the 0.0 cm mark on the metre ruler is level with the surface of the sand. • Hold the ball at a height of 20.0 cm above the surface of the sand as shown in Fig. 5.2. cm 22 21 20 19 18 Fig. 5.2 • Drop the ball so that it falls into the sand. Do not throw the ball downwards. • Carefully remove the ball from the sand. • Use a ruler to measure the diameter of the crater you make as shown in Fig. 5.3. • Record in Table 5.1 the diameter in mm to the nearest mm. crater cm diameter Fig. 5.3 Table 5.1 height of ball diameter of crater / cm / mm 20.0 40.0 60.0 80.0 100.0 Repeat the procedure for heights of 40.0 cm, 60.0 cm, 80.0 cm, and 100.0 cm. [4] (b) State the relationship between the height of the ball and the diameter of the crater. ................................................................................................................................................... ............................................................................................................................................. [1] (c) (i) One possible error in this investigation is that the metre ruler is not placed perpendicular to the surface of the sand. Name one suitable piece of equipment which shows if the metre ruler is perpendicular to the surface of the sand. ..................................................................................................................................... [1] (ii) State one other source of error in your investigation. Suggest how this error is reduced. error ................................................................................................................................... ........................................................................................................................................... suggestion ......................................................................................................................... ........................................................................................................................................... [2] (d) (i) A student repeats the investigation but uses a larger metal ball and flour instead of sand. Table 5.2 shows the results the student obtains. Table 5.2 diameter of crater height of ball / mm / cm trial 1 trial 2 trial 3 average 20.0 18 18 18 18 40.0 22 24 24 60.0 27 30 28 28 80.0 32 27 37 32 100.0 40 42 41 41 Calculate the average diameter of the crater for the 40.0 cm height. Record your answer in Table 5.2. [1] (ii) One of the calculated average diameters is incorrect because an anomalous value is used in the calculation. Circle the incorrect average diameter in Table 5.2. Explain the error the student makes. ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ..................................................................................................................................... [2] (e) A student investigates the effect of the volume V of a ball on the diameter of the crater formed. The student drops two balls, X and Y, from the same height and measures the diameters of the craters. Table 5.3 shows the results the student obtains. Table 5.3 volume of ball diameter of crater / cm3 / mm ball X 16.8 37 ball Y 62 (i) The radius r of ball Y is 2.0 cm. Calculate the volume V of ball Y. Use the equation shown. V = 4.2 × r 3 Record this value in Table 5.3. [1] (ii) The student concludes that the volume of the ball is proportional to the diameter of the crater. State if the student is correct. Explain your answer. statement .......................................................................................................................... explanation ........................................................................................................................ ........................................................................................................................................... [1] [Total: 13]

Mark scheme: 5(a) diameter recorded for 20.0 cm height ; 4 5 results ; results increase down the table ; all results in mm AND 10 to 200 ; 5(b) relationship correct ; 1 5(c)(i) protractor / set square ; 1 5(c)(ii) source of error identified ; 2 suggestion is appropriate ; e.g. (difficult to measure) crater is not circular / irregular / difficult to tell edge ; measure several ‘diameters’ on the (same) crater and average ; OR crater crumbles / sand moves when ball removed / diameter changes as removes ball / hands may make crater larger ; use damp sand / use compasses/divider to determine diameter ; OR hand wobbles when dropping ; use steel ball bearing and electromagnet / hang from a string and cut string ; OR difficult to measure diameter of crater as ruler cannot be laid on the sand ; use compasses/divider/smaller rule ; OR some of sand spills from the tray ; refill / weigh the sand ; 5(d)(i) 23 ; 1 5(d)(ii) 32 circled ; 2 27 is anomalous / outlier ; 5(e)(i) 33.6 ; 1 5(e)(ii) no and ratio V / d or d / V is not constant ; 1

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6 The rate of cooling of hot water in a beaker depends upon the number of layers of insulating newspaper wrapped around the beaker. Plan an investigation to find the relationship between the rate of cooling of hot water and the number of layers of newspaper wrapped around the beaker. You are provided with: • a stop-watch • a beaker • a supply of hot water • several pages from a newspaper. You are not required to do this investigation. In your plan, include: • any other apparatus you will need • a brief description of the method • the measurements you will make and how you make them as valid as possible • the variables you will control • how you will process your results to reach a conclusion. You may include a table that can be used to record results. You are not required to include any results. .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .................................................................................................................................................... [7] NOTES FOR USE IN QUALITATIVE ANALYSIS Tests for anions anion test test result carbonate, CO32− add dilute acid, then test for carbon effervescence, carbon dioxide dioxide gas 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 iodide, I – acidify with dilute nitric acid, then yellow ppt. [in solution] add aqueous silver nitrate nitrate, NO3− add aqueous sodium hydroxide, ammonia produced [in solution] then aluminium foil; warm carefully sulfate, SO42− acidify with dilute nitric acid, then white ppt. [in solution] add aqueous barium 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, ppt. turns brown near surface on ppt. turns brown near surface on standing standing iron(III), Fe3+ red-brown ppt., insoluble in excess red-brown ppt., insoluble in excess zinc, Zn2+ white ppt., soluble in excess, giving white ppt., soluble in excess, giving a colourless solution a 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 (if one section is omitted then max 6 etc.) 7 apparatus thermometer and temperature measured in plan ; measuring cylinder and volume/amount measured in plan ; method hot water in beaker and wrap newspaper and measure temperature and time for a minimum of 2 thicknesses of paper ; measurements temperature change after specified time/times or time for a specified temperature change ; repeat each number of layers to identify/exclude anomalies ; (minimum of) 5 layers ; control variables initial temperature of the hot water ; volume of water ; temperature of the surroundings / room temperature ; size / shape of beaker ; conclusion calculate rate temp change over time ; plot graph of rate (of cooling) against (number of) layers ; describe possible shapes of graph e.g. straight line – linear relationship / straight line through origin – proportional etc. ; when newspaper layers increase does rate (of cooling) increase / decrease or stay the same ;

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