Cambridge IGCSE Science - Combined 0653 — 2016 Oct/Nov Paper 6 · Variant 3

This document consists of 19 printed pages and 1 blank page. DC (SC) 138055/1 © UCLES 2016 [Turn over Cambridge International Examinations Cambridge International General Certificate of Secondary Education * 2 9 1 0 2 3 3 3 2 5 * COMBINED SCIENCE 0653/63 Paper 6 Alternative to Practical October/November 2016 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. You may use an HB pencil for any diagrams or graphs. Do not use staples, paper clips, glue or correction fluid. DO NOT WRITE IN ANY BARCODES. Answer all questions. Electronic calculators may be used. You may lose marks if you do not show your working or if you do not use appropriate units. 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.

2 0653/63/O/N/16 © UCLES 2016 1 A student investigates the nutrient content of soft cheese and tomatoes. He has access to three testing solutions. Benedict’s solution biuret solution iodine solution He adds a small amount of distilled water to some soft cheese and stirs it with a stirring rod so that it loosens and can be poured. He pours the cheese into each of three test-tubes and tests them for the nutrients shown in Table 1.1. (a) Complete Table 1.1 to show which solution he uses for each test and whether or not he needs to use heat for the test. Table 1.1 nutrient tested for testing solution is heat required? (yes / no) protein reducing sugar starch [3] (b) He obtains a positive result with the protein test only. Complete Table 1.2 to show his observations. Table 1.2 testing solution used initial colour colour after test Benedict’s blue biuret blue iodine brown [2]

3 0653/63/O/N/16 © UCLES 2016 [Turn over (c) He chops the tomato flesh into small pieces and adds some to each of three clean test-tubes. He tests the tomato for the nutrients shown in Table 1.1. He obtains positive results for starch and reducing sugar. Complete Table 1.3 to show his observations. Table 1.3 testing solution used initial colour colour after test Benedict’s blue biuret blue iodine brown [2] (d) Plan an investigation to compare the reducing sugar content of lemon juice and lemonade (lemon soda). In your answer you should suggest the observations that would enable you to state which has the higher concentration of reducing sugar. … … … … … …[3]

4 0653/63/O/N/16 © UCLES 2016 BLANK PAGE

5 0653/63/O/N/16 © UCLES 2016 [Turn over 2 A student investigates how the concentration of hydrochloric acid affects the speed of reaction between calcium carbonate and hydrochloric acid. She is provided with marble chips (calcium carbonate) and solutions of hydrochloric acid of concentration, 1.00 Q, 0.75 Q and 0.50 Q, where Q is a unit of concentration. (a) • She places limewater in a test-tube. • She places a delivery tube in the limewater. • She places hydrochloric acid of concentration 1.00 Q in another test-tube. • She adds ten marble chips to the acid in the test-tube and starts a stopclock. • She quickly attaches the bung of the delivery tube so that the gas produced passes into the limewater as shown in Fig. 2.1. hydrochloric acid bung delivery tube limewater marble chips Fig. 2.1 • She stops the stopclock at the first appearance of a white precipitate in the limewater. • She records in Table 2.1 this time t1 to the nearest second for concentration 1.00 Q. • She repeats the procedure above and records in Table 2.1 the time t2 to the nearest second for concentration 1.00 Q. The stopclock readings of t1 and t2 for concentration 1.00 Q are shown in Fig. 2.2. Read the stopclocks to the nearest second and record the values in Table 2.1 on page 6. [2] min t1 sec min t2 sec readings for hydrochloric acid of concentration 1.00 Q Fig. 2.2

6 0653/63/O/N/16 © UCLES 2016 Table 2.1 concentration of hydrochloric acid / Q time t1 for white ppt. to appear / s time t2 for white ppt. to appear / s average time ta for white ppt. to appear / s speed of reaction, 1 ta 1.00 0.75 49 57 53 0.50 82 86 84 (b) She repeats the procedure in (a), firstly using hydrochloric acid of concentration 0.75 Q and then using concentration 0.50 Q. The results of these experiments are shown in Table 2.1. (i) Calculate the average time ta for the concentration of 1.00 Q and record the value in Table 2.1. [1] (ii) For each concentration of hydrochloric acid calculate 1 ta . 1 ta is a measure of the speed of reaction. Record in Table 2.1 the values to three decimal places. [1]

7 0653/63/O/N/16 © UCLES 2016 [Turn over (c) (i) On the grid provided, plot a graph of the speed of reaction against the concentration of hydrochloric acid used. Draw the most appropriate straight line or curve through the origin. [3] 0 0 0.20 0.40 0.60 0.80 1.00 0.10 0.30 0.50 concentration of hydrochloric acid / Q 0.70 0.90 speed of reaction, 1 ta (ii) Using your graph state the relationship between the speed of the reaction and the concentration of hydrochloric acid. … …[1]

8 0653/63/O/N/16 © UCLES 2016 (d) The student considers the results in Table 2.1. She is unhappy about the results for one of the concentrations of hydrochloric acid. Suggest which concentration and state why the times are less satisfactory than the other results. concentration … reason … … [1] (e) Explain why it is important to replace the marble chips for each different experiment. … …[1]

9 0653/63/O/N/16 © UCLES 2016 [Turn over 3 A student investigates the total resistance of different combinations of identical resistors. She sets up the circuit shown in Fig. 3.1. A R R R switch power source X Y Fig. 3.1 (a) She switches on the circuit by closing the switch and measures the potential difference V between X and Y and then switches off by opening the switch. (i) Complete Fig. 3.1, to show how the voltmeter is connected to measure the potential difference V. [2] (ii) Fig. 3.2 shows the voltmeter reading. 0 1 2 3 V Fig. 3.2 Record the voltmeter reading V. V = … V [1]

10 0653/63/O/N/16 © UCLES 2016 (iii) The student closes the switch, records the current I shown on the ammeter and then opens the switch. Fig. 3.3 shows the ammeter reading. A 0.6 0.8 1.0 0.4 0.2 0 Fig. 3.3 Record the ammeter reading I. I = … A [1] (iv) Calculate the total resistance RT of the combination of the three resistors in Fig. 3.1 using the equation: RT = V I Include the unit of resistance in your answer. RT = … unit = … [2] (b) The student disconnects the resistors from the circuit and reconnects the resistors in the circuit so that all three resistors are in series between points X and Y as shown in Fig. 3.4. A R R R switch power source X Y Fig. 3.4 She closes the switch and measures the potential difference VS between X and Y and the current IS. Her readings are shown in Table 3.1 on page 11.

11 0653/63/O/N/16 © UCLES 2016 [Turn over Table 3.1 potential difference VS / V current IS / A 1.8 0.12 Calculate the total resistance RS of the series combination of the three resistors using the equation: RS = VS IS RS = …[1] (c) Theory suggests that because the resistors are identical: RT = 0.5 RS State whether the student’s results support the theory and justify your statement by reference to the results. statement … justification … … [1] (d) Explain why it is important to switch the circuit off between taking readings. … …[1] (e) Predict how the reading on the ammeter changes if the three resistors in Fig. 3.4 are replaced by just one of the resistors connected between X and Y. Assume that the potential difference between X and Y stays the same. … …[1]

12 0653/63/O/N/16 © UCLES 2016 4 A student investigates gas exchange in animals and plants. She uses a bicarbonate indicator to detect changes in the concentration of carbon dioxide. The chart in Fig. 4.1 shows the colour of the indicator for different concentrations of carbon dioxide. concentration of carbon dioxide low medium high colour of bicarbonate indicator purple red yellow Fig. 4.1 • The student sets up four test-tubes as shown in Fig. 4.2. A – pond weed water with bicarbonate indicator water with bicarbonate indicator B – tadpoles C – pond weed and tadpoles D – no living organism Fig. 4.2 • She places the test-tubes in the light. • She returns 2 hours later and records her observations in Table 4.1. Table 4.1 test-tube initial colour final colour change in carbon dioxide concentration (increase / decrease / no change) A red purple B red yellow C red red no change D red red

13 0653/63/O/N/16 © UCLES 2016 [Turn over (a) Fill in the last column of Table 4.1 to show what happened to the carbon dioxide concentrations after 2 hours. [1] (b) (i) Explain why the concentration of carbon dioxide changes in test-tube A. … …[1] (ii) Explain why the concentration of carbon dioxide changes in test-tube B. … …[1] (iii) Suggest why the concentration of carbon dioxide remains the same in test-tube C. … …[1] (c) Explain the purpose of test-tube D. … …[1] (d) (i) The student keeps the four test-tubes at the same temperature. State how this can be done and suggest a suitable temperature. method … temperature … [2] (ii) Suggest three other factors that the student needs to keep constant when setting up this experiment. 1 … 2 … 3 … [3]

14 0653/63/O/N/16 © UCLES 2016 5 The science class are investigating the properties of three oxides J, K and L. J is a solid, K is a liquid and L is a gas. Fig. 5.1 shows the apparatus. The teacher has not told the students the names of the oxides. solid oxide J liquid oxide K gaseous oxide L Fig. 5.1 (a) A student experiments with these three oxides. Oxide J is a black solid. • He thinks that oxide J contains oxygen combined with a metal. • He mixes the oxide with powdered charcoal and strongly heats the mixture in a crucible. • The oxide turns from black to a brown-pink coloured solid M. • The student is testing the brown-pink solid to see if it will conduct electricity. • He has started to draw a circuit diagram as shown in Fig. 5.2. (i) Complete Fig. 5.2 by adding two electrical (circuit) symbols for components that will allow the student to show that solid M conducts electricity. electrodes solid M [2] Fig. 5.2 (ii) State the name of solid oxide J. name …[1]

15 0653/63/O/N/16 © UCLES 2016 [Turn over (b) A student sets up apparatus to measure the boiling point of oxide K. When heated, oxide K boils. The student wants the vapour to pass into the condenser. Fig. 5.3 shows part of the apparatus he sets up. oxide K oxide K heat water out water in condenser Fig. 5.3 (i) Complete Fig. 5.3 including a thermometer. Draw the bulb of the thermometer in the correct place so that the accurate boiling point of the liquid will be shown on the scale. [2]

16 0653/63/O/N/16 © UCLES 2016 (ii) Fig. 5.4 shows the thermometer scale when oxide K is boiling. 100 °C 95 90 Fig. 5.4 Read the scale and record the boiling point of the oxide K. boiling point = …°C [1] (iii) The student concludes that oxide K is water. Another student says that it cannot be water because water boils at 100 °C. Suggest how the student can justify his conclusion that the oxide K is water. … …[1] (c) A student adds some limewater to a gas-jar of oxide L and replaces the lid. He shakes the gas-jar and the limewater turns milky. State the name of oxide L. name … [1] (d) The procedure used in (a) does not work for all metal oxides. An alternative procedure is to react the solid oxide with nitric acid to produce metal ions in solution. State how a student can identify the metal ion in the solution produced from solid M. In your answer include the testing reagent and how the metal ion may be identified from the observations. … … … …[2]

17 0653/63/O/N/16 © UCLES 2016 [Turn over Please turn over for Question 6.

18 0653/63/O/N/16 © UCLES 2016 6 A student is given three liquids labelled R, S and T. The student has a mass balance, a 50 cm3 measuring cylinder and samples of the three liquids. • She places the measuring cylinder on the balance and weighs it. She records the mass in Table 6.1. • She adds liquid R to the measuring cylinder until the total mass is approximately 60 g. She records the actual mass in Table 6.1. • She measures the volume of liquid R. • She repeats the procedure using samples of the other two liquids with the same measuring cylinder. (a) (i) Fig. 6.1 shows the measuring cylinders for liquids R and S. Read the volumes to the nearest 0.5 cm3 and record the values in Table 6.1. 40 cm3 cm3 30 20 50 40 30 liquid R liquid S [2] Fig. 6.1 Table 6.1 liquid R S T mass of measuring cylinder + liquid / g 60.1 59.9 60.0 mass of measuring cylinder / g 25.5 25.5 25.5 mass of liquid / g 34.6 34.4 34.5 volume of liquid in measuring cylinder / cm3 34.5 density of liquid / g per cm3 1.0

19 0653/63/O/N/16 © UCLES 2016 [Turn over (ii) Explain how the student makes sure that her readings from the measuring cylinder are as accurate as possible. You may draw a diagram to help your explanation. … …[1] (b) Use the data in Table 6.1 and the formula below to calculate the densities of liquids R and S. Record the densities in Table 6.1 to one decimal place. density = mass volume [2] (c) (i) Name a piece of apparatus that the student could use to add the last few drops of liquid to the measuring cylinder so that the total mass is close to 60 g. …[1] (ii) Suggest a reason why the student does not need to make the total mass exactly 60.0 g to calculate density. … …[1] (iii) The student knows that her results for the densities of the liquids will be slightly inaccurate. She repeats the experiment two more times, giving three results for the volumes and masses of each liquid. Suggest how she can use the results of the three experiments to find more reliable values for the densities of the liquids. … …[1]

20 0653/63/O/N/16 © UCLES 2016 Permission to reproduce items where third-party owned material protected by copyright is included has been sought and cleared where possible. Every reasonable effort has been made by the publisher (UCLES) to trace copyright holders, but if any items requiring clearance have unwittingly been included, the publisher will be pleased to make amends at the earliest possible opportunity. To avoid the issue of disclosure of answer-related information to candidates, all copyright acknowledgements are reproduced online in the Cambridge International Examinations Copyright Acknowledgements Booklet. This is produced for each series of examinations and is freely available to download at www.cie.org.uk after the live examination series. Cambridge International Examinations is part of the Cambridge Assessment Group. Cambridge Assessment is the brand name of University of Cambridge Local Examinations Syndicate (UCLES), which is itself a department of the University of Cambridge. (d) (i) Liquid T is water. Hydrocarbon oils float on water. State which of the liquids, R or S, is a hydrocarbon oil and give a reason for your answer. liquid … because … …[1] (ii) The third liquid is an aqueous solution of a salt. The student pours 10 cm3 of each of the liquids R, S and T into one new measuring cylinder. She stirs the mixture and allows it to settle. Complete Fig. 6.2 to show what she would observe when the mixture has settled. Label your diagram. 50 cm3 40 30 20 10 [1] Fig. 6.2

® IGCSE is the registered trademark of Cambridge International Examinations. This document consists of 7 printed pages. © UCLES 2016 [Turn over Cambridge International Examinations Cambridge International General Certificate of Secondary Education COMBINED SCIENCE 0653/63 Paper 6 Alternative to Practical October/November 2016 MARK SCHEME Maximum Mark: 60 Published This mark scheme is published as an aid to teachers and candidates, to indicate the requirements of the examination. It shows the basis on which Examiners were instructed to award marks. It does not indicate the details of the discussions that took place at an Examiners’ meeting before marking began, which would have considered the acceptability of alternative answers. Mark schemes should be read in conjunction with the question paper and the Principal Examiner Report for Teachers. Cambridge will not enter into discussions about these mark schemes. Cambridge is publishing the mark schemes for the October/November 2016 series for most Cambridge IGCSE®, Cambridge International A and AS Level components and some Cambridge O Level components.

Page 2 Mark Scheme Syllabus Paper Cambridge IGCSE – October/November 2016 0653 63 © UCLES 2016 Question Answers Marks 1(a) Nutrient tested for Testing solution Heat needed? (Yes / no) Protein Biuret no Reducing sugar Benedict’s yes Starch Iodine no 3 correct reagents = 2, 1 correct = 1;; 1 mark for heat for reducing sugar only ; 3 1(b) Testing solution used Initial colour Colour after test Benedict’s solution Blue blue biuret solution Blue purple/lilac iodine brown brown purple / lilac for protein ; negative colours brown and blue ; 2 1(c) Benedict's: yellow / green / orange / red ; iodine: blue-black ; 2 1(d) same volume of juice and lemonade ; same volume of Benedict’s solution ; yellow / green for small amount of reducing sugar OR orange / red for high(er) amount of reducing sugar ; 3 Total: 10

Page 3 Mark Scheme Syllabus Paper Cambridge IGCSE – October/November 2016 0653 63 © UCLES 2016 Question Answers Marks 2(a) 30 ; 32 ; 2 2(b)(i) 31 ; 1 2(b)(ii) 0.032 0.019 / 0.018, 0.012 / 0.011 ; 1 2(c)(i) linear scale for vertical axis using at least half of the grid ; all three points plotted correctly to within half a small square ; best appropriate straight line or curve through the origin ; 3 2(c)(ii) as concentration increases speed increases ; 1 2(d) 0.75 and difference between them is much greater than difference between other pairs / % difference greater than other pairs / % difference greater than 10% ; 1 2(e) (reacted chips have) smaller surface area / (already reacted chips will) react slower ; 1 Total: 10

Page 4 Mark Scheme Syllabus Paper Cambridge IGCSE – October/November 2016 0653 63 © UCLES 2016 Question Answers Marks 3(a)(i) correct symbol for voltmeter ; correct parallel (voltmeter) connection between X and Y ; 2 3(a)(ii) 1.9 (V) ; 1 3(a)(iii) 0.24 (A) ; 1 3(a)(iv) 7.9 ; Unit Ω / ohm ; 2 3(b) 15 (Ω) ; 1 3(c) YES (no mark) and values of RT and 0.5 RS are close enough / difference can be attributed to experimental error ; 1 3(d) resistors become hot / temperature affects resistance ; 1 3(e) increases ; 1 Total: 10

Page 5 Mark Scheme Syllabus Paper Cambridge IGCSE – October/November 2016 0653 63 © UCLES 2016 Question Answers Marks 4(a) Test- tube Initial colour Final Colour Change in CO2 concentration (increase / decrease / no change) A red purple decrease B red yellow increase C red red (no change) D red red no change changes for A and B correct ; anything other than no change for D = no marks 1 4(b)(i) photosynthesis (removes CO2) ; 1 4(b)(ii) respiration (produces CO2) ; 1 4(b)(iii) rate of photosynthesis and respiration is matched ; 1 4(c) control / to show no change without organisms ; 1 4(d)(i) water bath ; between 10–40 °C ; 2 4(d)(ii) volume of water ; number / size of tadpoles ; size of pondweed ; amount of indicator ; light intensity ; type of water ; type of pondweed ; max 3 Total: 10

Page 6 Mark Scheme Syllabus Paper Cambridge IGCSE – October/November 2016 0653 63 © UCLES 2016 Question Answers Marks 5(a)(i) symbol for cell / DC power supply ; symbol for ammeter or lamp ; 2 5(a)(ii) copper oxide / CuO ; 1 5(b)(i) thermometer and stopper ; thermometer bulb opposite to the side-arm ; 2 5(b)(ii) 99.5 (°C) ; 1 5(b)(iii) (0.5 less than 100) within experimental error / inaccuracy of thermometer / height above sea level ; 1 5(c) carbon dioxide / CO2 ; 1 5(d) sodium hydroxide solution / add ammonia solution ; colour of ppt. / specific example, e.g. blue ppt. = Cu2+ ; 2 Total: 10 Question Answers Marks 6(a)(i) 29.0 ; 41.0 ; 2 6(a)(ii) eye level / bottom of meniscus ; 1 6(b) 1.2 (1.193103448275862) ; 0.8 (0.8390243902439024463) ; 2 6(c)(i) (teat / dropping) pipette ; 1 6(c)(ii) formula takes it into account ; 1

Page 7 Mark Scheme Syllabus Paper Cambridge IGCSE – October/November 2016 0653 63 © UCLES 2016 Question Answers Marks 6(c)(iii) find the average / mean (of the three results for each liquid) ; 1 6(d)(i) S and because it is less dense than water / liquid T ; 1 6(d)(ii) oil / S on top (ecf) with one line at 20 ; (water and salt solution or water and solution R) 1 Total: 10