Cambridge A Level Physical Science 8780 — 2017 Oct/Nov Paper 4 · Variant 1

* 4 7 5 9 2 1 9 8 8 6 * This document consists of 12 printed pages. DC (SC/SW) 139277/4 © UCLES 2017 [Turn over PHYSICAL SCIENCE 8780/04 Paper 4 Advanced Practical Skills October/November 2017 1 hour 30 minutes Candidates answer on the Question Paper. Additional Materials: As listed in the Confidential Instructions READ THESE INSTRUCTIONS FIRST Write your Centre number, candidate number and name on all the work you hand in. Give details of the practical session and laboratory, where appropriate, in the boxes provided. Write in dark blue or black pen. You may use a pencil for any diagrams or graphs. Do not use staples, paper clips, glue or correction fluid. DO NOT WRITE IN ANY BARCODES. Answer both questions. You will be allowed to work with the apparatus for a maximum of 45 minutes for each question. Electronic calculators may be used. You are advised to show all working in calculations. Use of a Data Booklet is unnecessary. Qualitative Analysis Notes are printed on pages 11 and 12. 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. Cambridge International Examinations Cambridge International Advanced Subsidiary Level For Examiner’s Use 1 2 Total Session Laboratory

2 8780/04/O/N/17 © UCLES 2017 1 In this experiment you will use a potential divider circuit to determine the resistance of an unknown resistor N. The circuit in Fig. 1.1 has been set up for you. A uniform resistance wire is taped to a metre rule. N 0 cm 100 cm moveable contact L resistance wire A switch S1 power supply P power supply Q switch S2 B C D E F 47 Ω 47 Ω 47 Ω 47 Ω 47 Ω 47 Ω X V metre rule Fig. 1.1 (a) The voltmeter is initially connected at point A. Close both switches S1 and S2. Place and hold the moveable contact on to the resistance wire at the 10 cm mark on the metre rule. Record the reading shown on the voltmeter. voltmeter reading … V Place and hold the moveable contact on to the wire at the 90 cm mark on the metre rule. Record the reading shown on the voltmeter. voltmeter reading … V [1] (b) Length L is the length of resistance wire between the 0 cm mark on the metre rule and the moveable contact when the voltmeter, connected at point A, has a reading of zero. (i) Adjust the position of the moveable contact on the resistance wire until you find the position at which the voltmeter reading is zero. Measure and record the length L. L = …cm [1]

3 8780/04/O/N/17 © UCLES 2017 [Turn over (ii) Use your apparatus to find the range of values of L for which the voltmeter reading is zero. range is from … cm to … cm. Use this range to determine the uncertainty in the value of L recorded in (b)(i). uncertainty = ± …cm [2] Open both switches S1 and S2. (c) You are going to determine the value of L with the voltmeter connected at points B, C, D, E and F. (i) There is a significant uncertainty in the measurement of length L. Describe how you will proceed to ensure that, for each position of the voltmeter, the distance L is as accurate as possible. … … … …[1]

4 8780/04/O/N/17 © UCLES 2017 (ii) Table 1.1 has been partly prepared, with the values of the resistance R between point X and the points A, B, C, D, E and F already recorded. Extend Table 1.1 to allow you to record all the readings you take and the accurate readings of L. [1] Table 1.1 voltmeter position resistance R / Ω A 47 B 94 C 141 D 188 E 235 F 282 (iii) Close both switches S1 and S2. Take appropriate measurements with the voltmeter connected at each of the points B, C, D, E and F to enable you to complete your extended Table 1.1. Include your readings for the voltmeter positioned at A, from (b). [2] Open both switches S1 and S2. (d) (i) On the grid provided, the axes have already been drawn and the origin has been labelled for you. Plot your accurate values of R / Ω on the y-axis and L / cm on the x-axis. Draw the straight line of best fit. [3] (ii) Calculate the gradient of the graph. Show your working. gradient = … [1]

5 8780/04/O/N/17 © UCLES 2017 [Turn over 0 resistance R / Ω length L / cm 0

6 8780/04/O/N/17 © UCLES 2017 (e) The relationship between R and L is of the form shown, where T and U are constants. R = TL + U Determine the values of T and U. Give appropriate units for each. T = … unit … U = … unit … [2] (f) From (e) deduce the resistance of the unknown resistor N. resistance = … Ω [1] [Total: 15]

7 8780/04/O/N/17 © UCLES 2017 [Turn over 2 (a) Solution P contains either chloride or sulfate ions. (i) Carry out tests on a 1 cm depth sample of solution P in a test-tube, to test for chloride ions. In a clean test-tube, carry out tests on a 1 cm depth sample of solution P, to test for sulfate ions. Record details of the reagents you used in the tests and your observations for each test in Table 2.1. Table 2.1 anion reagents used observations chloride sulfate Identify the anion present in solution P. anion present … [2]

8 8780/04/O/N/17 © UCLES 2017 (ii) Solution P contains magnesium ions and ions of a second metal. Test a 1 cm depth sample of solution P in a clean test-tube with aqueous sodium hydroxide. In a clean test-tube, test a 1 cm depth sample of solution P with aqueous ammonia. Record your observations for each test in Table 2.2. Table 2.2 reagent observations aqueous sodium hydroxide aqueous ammonia Identify the second metal ion present in solution P. second metal ion present … [3]

9 8780/04/O/N/17 © UCLES 2017 (b) You are provided with solutions X, Y and Z. Solution X is 1.00 mol dm−3 sulfuric acid. Solution Y is alkaline. Solution Z is acidic. (i) Experiment 1. Step 1. Place a clean polystyrene cup into a 250 cm3 beaker. The beaker is to prevent the cup from falling over. Step 2. Use a 50 cm3 measuring cylinder to transfer 40.0 cm3 of X into the polystyrene cup. Step 3. Measure the temperature of X to 0.2 °C and record this initial temperature in Table 2.3. Step 4. Use a clean measuring cylinder to add 50.0 cm3 of Y into the polystyrene cup. Step 5. Stir the mixture with the thermometer and measure the highest temperature reached. Record this in Table 2.3. Table 2.3 experiment initial temperature / °C highest temperature / °C temperature rise / °C 1 2 [4] (ii) Experiment 2. Repeat steps 1 to 5 of experiment 1 using solution Z instead of solution X. Complete Table 2.3 by calculating the temperature rises for experiments 1 and 2. Suggest why the temperature rises in experiments 1 and 2 are different. … … …[1] [Turn over

10 8780/04/O/N/17 © UCLES 2017 (c) Suggest what effect using a glass beaker instead of a polystyrene cup in experiment 1 might have on the temperature rise. Give a reason for your answer. … …[1] (d) There is 1.00 mol of sulfuric acid in 1000 cm3 of solution X. Solution Y is in excess in both experiments. Solution Z was prepared by reacting magnesium ribbon with 1.00 mol dm−3 sulfuric acid. The equation for the reaction is shown. Mg(s) + H2SO4(aq) MgSO4(aq) + H2(g) (i) Calculate the concentration of sulfuric acid in Z by using the ratio of temperature rises in experiments 1 and 2. concentration of sulfuric acid in Z … mol dm−3 [1] (ii) Calculate the number of moles of sulfuric acid in 100 cm3 of Z. This is the remaining sulfuric acid which did not react with the magnesium ribbon when solution Z was prepared. moles of sulfuric acid in 100 cm3 of Z … [1] (iii) Calculate the number of moles of sulfuric acid in 100 cm3 of Z that reacted with the magnesium ribbon. moles of sulfuric acid that reacted with magnesium ribbon … [1] (iv) Calculate the mass of the magnesium ribbon used to make 100 cm3 of Z. mass of magnesium ribbon … g [1] [Total: 15]

11 8780/04/O/N/17 © UCLES 2017 Qualitative Analysis Notes Key: [ppt. = precipitate] 1 Reactions of aqueous cations cation reaction with NaOH(aq) NH3(aq) aluminium, Al3+(aq) white ppt. soluble in excess white ppt. insoluble in excess ammonium, NH4 +(aq) no ppt. ammonia produced on heating – barium, Ba2+(aq) no ppt. (if reagents are pure) no ppt. calcium, Ca2+(aq) white ppt. with high [Ca2+(aq)] no ppt. chromium(III), Cr3+(aq) grey-green ppt. soluble in excess giving dark green solution grey-green ppt. insoluble in excess copper(II), Cu2+(aq) pale blue ppt. insoluble in excess blue ppt. soluble in excess giving dark blue solution iron(II), Fe2+(aq) green ppt. turning brown on contact with air insoluble in excess green ppt. turning brown on contact with air insoluble in excess iron(III), Fe3+(aq) red-brown ppt. insoluble in excess red-brown ppt. insoluble in excess magnesium, Mg2+(aq) white ppt. insoluble in excess white ppt. insoluble in excess manganese(II), Mn2+(aq) off-white ppt. rapidly turning brown on contact with air insoluble in excess off-white ppt. rapidly turning brown on contact with air insoluble in excess zinc, Zn2+(aq) white ppt. soluble in excess white ppt. soluble in excess

12 8780/04/O/N/17 © UCLES 2017 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. 2 Reactions of anions ion reaction carbonate, CO3 2– CO2 liberated by dilute acids chloride, Cl –(aq) gives white ppt. with Ag+(aq) (soluble in NH3(aq)) bromide, Br –(aq) gives (pale) cream ppt. with Ag+(aq) (partially soluble in NH3(aq)) iodide, I –(aq) gives yellow ppt. with Ag+(aq) (insoluble in NH3(aq)) nitrate, NO3 –(aq) NH3 liberated on heating with OH–(aq) and Al foil nitrite, NO2 –(aq) NH3 liberated on heating with OH–(aq) and Al foil NO liberated by dilute acids (colourless NO (pale) brown NO2 in air) sulfate, SO4 2–(aq) gives white ppt. with Ba2+(aq) or with Pb2+ (insoluble in excess dilute strong acids) sulfite, SO3 2–(aq) SO2 liberated with dilute acids, gives white ppt. with Ba2+(aq) (soluble in excess dilute strong acid) 3 Tests for gases gas test and test result ammonia, NH3 turns damp red litmus paper blue carbon dioxide, CO2 gives a white ppt. with limewater (ppt. dissolves with excess CO2) chlorine, Cl 2 bleaches damp litmus paper hydrogen, H2 ‘pops’ with a lighted splint oxygen, O2 relights a glowing splint sulfur dioxide, SO2 turns acidified aqueous potassium manganate(VII) from purple to colourless

® IGCSE is a registered trademark. This document consists of 3 printed pages. © UCLES 2017 [Turn over Cambridge Assessment International Education Cambridge International Advanced Subsidiary Level PHYSICAL SCIENCES 8780/04 Paper 4 Advanced Practical Skills October/November 2017 MARK SCHEME Maximum Mark: 30 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 International will not enter into discussions about these mark schemes. Cambridge International is publishing the mark schemes for the October/November 2017 series for most Cambridge IGCSE®, Cambridge International A and AS Level components and some Cambridge O Level components.

8780/04 Cambridge International AS Level – Mark Scheme PUBLISHED October/November 2017 © UCLES 2017 Page 2 of 3 Question Answer Marks 1(a) one voltmeter reading positive AND the other negative 1 1(b)(i) (L =) 30 ± 10 (cm) 1 1(b)(ii) two values of L within 1 cm apart AND including the value given in (b)(i) 1 (uncertainty = ±) half the range given in (b)(ii) 1 1(c)(i) EITHER take two or more readings AND average OR move moveable contact from beginning to end of zero range AND take the midpoint 1 1(c)(ii) table with heading for L with units AND evidence of repeat readings 1 1(c)(iii) 5 or 6 values for L (all increasing) 1 all values of L to 1 mm precision 1 1(d)(i) axes half or more of graph paper used in both x and y directions, no awkward scales 1 plotting all points plotted correctly to within ½ a square 1 line of best fit single line of best fit 1 1(d)(ii) points identified correctly AND correct use of change in R ÷ change in L 1 1(e) (T =) the value of the gradient AND correct unit 1 (U =) the y-intercept AND correct unit 1 1(f) numerical U in range of 65 to 95 1

8780/04 Cambridge International AS Level – Mark Scheme PUBLISHED October/November 2017 © UCLES 2017 Page 3 of 3 Question Answer Marks 2(a)(i) silver nitrate AND no precipitate / no reaction 1 barium nitrate / chloride AND white precipitate 1 (anion present =) sulfate (no mark) 2(a)(ii) red-brown precipitate AND insoluble in excess for sodium hydroxide 1 red-brown precipitate AND insoluble in excess for ammonia 1 iron(III) / Fe3+ 1 2(b)(i) 4 temperature readings 1 all recorded to suitable precision of 1 decimal place 1 2 temperature increases correctly calculated 1 experiment 2 increase smaller than experiment 1 increase 1 2(b)(ii) Z more dilute / less acidic than X 1 2(c) smaller temperature rise AND greater heat energy lost / poorer insulation 1 2(d)(i) calculation of molarity from ratio of temperature rises 1 2(d)(ii) calculation of moles sulfuric acid in 100 cm3 of Z 1 2(d)(iii) calculation of moles of sulfuric acid which reacted with magnesium 1 2(d)(iv) mass of magnesium 1