Cambridge IGCSE Sciences - Co-ordinated (Double) 0654 — 2013 May/June Paper 3 · Variant 1

This document consists of 34 printed pages and 2 blank pages. IB13 06_0654_31/3RP © UCLES 2013 [Turn over *3484444856* UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS International General Certificate of Secondary Education CO-ORDINATED SCIENCES 0654/31 Paper 3 (Extended) May/June 2013 2 hours 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 a 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. A copy of the Periodic Table is printed on page 36. 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 © UCLES 2013 0654/31/M/J/13 For Examiner's Use 1 (a) Table 1.1 shows the numbers of protons, neutrons and electrons in four atoms, A, B, C and D. Table 1.1 atom protons neutrons electrons A 2 2 2 B 1 1 1 C 1 0 1 D 2 1 2 (i) Explain which one of the atoms, A, B, C or D, has the highest nucleon number (mass number). atom explanation [1] (ii) Explain which pair of atoms chosen from A, B, C and D are isotopes of helium. atom and atom explanation [2]

3 © UCLES 2013 0654/31/M/J/13 [Turn over For Examiner's Use (b) Fig. 1.1 shows containers of hydrogen and helium. H2 He hydrogen molecule helium atom Fig. 1.1 (i) Describe, in terms of electrons, how a chemical bond forms between two hydrogen atoms. You may draw a diagram of a hydrogen molecule if it helps you to answer this question. [2] (ii) Explain why helium exists as single atoms and not as molecules. [1]

4 © UCLES 2013 0654/31/M/J/13 For Examiner's Use (c) Hydrogen is often included in the reactivity series of metals. Use the idea of reactivity to explain the observations shown in Fig. 1.2. dilute hydrochloric acid burning splint zinc pop dilute hydrochloric acid silver no reaction Fig. 1.2 [3]

5 © UCLES 2013 0654/31/M/J/13 [Turn over Please turn over for Question 2.

6 © UCLES 2013 0654/31/M/J/13 For Examiner's Use 2 (a) A fishing boat is floating on the sea. The fishing boat uses echo sounding to detect a shoal of fish. This is shown in Fig. 2.1. shoal of fish Fig. 2.1 Short pulses of sound are sent out from the boat. The echo from the shoal of fish is detected by a receiver on the boat 0.2 seconds later. Sound waves travel through water at a speed of 1600 m / s. (i) Calculate the distance of the shoal of fish below the boat. State the formula that you use and show your working. formula working [2] (ii) The sound waves have a wavelength of 0.25 m. Calculate the frequency of the waves. State the formula that you use and show your working. formula working [2]

7 © UCLES 2013 0654/31/M/J/13 [Turn over For Examiner's Use (b) Water waves are a renewable energy resource. Outline two advantages of using renewable energy resources. 1 2 [2] (c) Fig. 2.2 shows an iceberg floating in the sea. water vapour in air air sea water ice Fig. 2.2 (i) Which material named on Fig. 2.2 best fits the statement below? “The particles are able to move, are randomly arranged and are closely packed.” [1] (ii) Name the process by which water molecules in the sea become water molecules in the air. [1]

8 © UCLES 2013 0654/31/M/J/13 For Examiner's Use 3 Fig. 3.1 shows an insect-pollinated flower cut in half. anther stigma ovule ovary wall petal filament sepal position of nectary Fig. 3.1 (a) (i) List the structures, labelled in Fig. 3.1, that are the male parts of the flower. [1] (ii) List the structures, labelled in Fig. 3.1, that are the female parts of the flower. [1] (iii) The nectary produces a sugar solution. Explain how the positions of the anthers, stigma and nectary help insect pollination to take place. [3]

9 © UCLES 2013 0654/31/M/J/13 [Turn over For Examiner's Use (b) After pollination, the ovule inside the ovary may be fertilised. The ovary develops into a fruit, and the ovule develops into a seed. (i) Draw a labelled diagram to show how one named fruit is dispersed by wind. [2] (ii) State why dispersal of seeds is important to a species of plant. [1]

10 © UCLES 2013 0654/31/M/J/13 For Examiner's Use 4 Petroleum (crude oil) and rock salt occur naturally in the Earth’s crust. (a) Petroleum is a mixture that contains thousands of different compounds. Many of these compounds are alkanes. Draw the structure of the alkane molecule that contains eight hydrogen atoms. Use short lines to represent covalent bonds. [2] (b) When petroleum is refined, it is separated into simpler mixtures. Fig. 4.1 shows a simplified diagram of a distillation column that is used to refine petroleum. hot petroleum A B C D Fig. 4.1 (i) Describe how the temperature inside the apparatus changes from position D to position A. [1]

11 © UCLES 2013 0654/31/M/J/13 [Turn over For Examiner's Use (ii) Explain, in terms of intermolecular forces and the size of molecules, why the average boiling point of the fraction at B differs from the average boiling point of the fraction at C. [3] (c) Rock salt contains mainly sodium chloride which is a compound of the alkali metal, sodium, and the halogen, chlorine. (i) Explain why the uncombined elements sodium and chlorine are not found in the Earth’s crust. [1] (ii) Describe the changes in electron configuration when sodium atoms (2,8,1) react with chlorine atoms (2,8,7) to form sodium chloride. [2]

12 © UCLES 2013 0654/31/M/J/13 For Examiner's Use (iii) Explain, in terms of its structure, why sodium chloride forms crystals which have a regular shape. You should draw a simple diagram of the structure to help you to answer this question. [3]

13 © UCLES 2013 0654/31/M/J/13 [Turn over Please turn over for Question 5.

14 © UCLES 2013 0654/31/M/J/13 For Examiner's Use 5 Milk is a liquid produced by cows, goats and other mammals, on which they feed their young. (a) Table 5.1 shows the mass of some of the substances in 100 g samples of milk from three mammals. Table 5.1 substance cow’s milk goat’s milk water-buffalo’s milk protein / g 3.2 3.1 4.5 fat / g 3.9 3.5 8.0 carbohydrate / g 4.8 4.4 4.9 calcium / mg 120 100 195 (i) Which substance shown in Table 5.1 is present in the samples of milk in the smallest quantity? [1] (ii) Suggest which substance, not shown in Table 5.1, is present in the samples of milk in the largest quantity. [1] (iii) Explain one way in which drinking water-buffalo’s milk might be better for a person’s health than drinking goat’s milk. [2] (iv) Explain one way in which drinking cow’s milk might be better for a person’s health than drinking water-buffalo’s milk. [2]

15 © UCLES 2013 0654/31/M/J/13 [Turn over For Examiner's Use (v) Explain why calcium does not need to be digested in the human alimentary canal. [1] (b) Milk can be used for making yoghurt. • Bacteria are added to the milk. The milk is kept at a temperature of 40 °C. • The bacteria convert lactose in the milk to lactic acid. • When the pH has reached about 4.5, the yoghurt is moved to a refrigerator at a temperature of 3 °C. (i) Explain why the milk is kept at a temperature of 40 °C after the bacteria have been added to it. [2] (ii) Suggest why the yoghurt is kept in a refrigerator at a temperature of 3 °C. [1] (iii) Milk has a pH of about 6.5. Explain why the pH of milk changes during the manufacture of yoghurt. [1]

16 © UCLES 2013 0654/31/M/J/13 For Examiner's Use 6 (a) In a store, two workers are lifting 5 kg bags of flour onto the shelves. There are five shelves, 0.4 m apart. The lowest shelf is 0.4 m from the floor. Fig. 6.1 shows the two workers. 0.4 m 0.4 m 0.4 m 0.4 m 0.4 m shelf 5 shelf 4 shelf 3 shelf 2 shelf 1 worker Y worker X Fig. 6.1 (i) Worker X lifts three bags from the floor to shelf 2. Worker Y lifts one bag from the floor to shelf 5. Worker X says that he has done more work than worker Y. Use calculations of the work done to explain whether or not he is correct. State the formula that you use. formula [2] (ii) Each worker lifts one bag from the floor to shelf 2. Worker X does this more quickly than worker Y. Which worker exerted the higher power during their lift? Explain your answer. [1]

17 © UCLES 2013 0654/31/M/J/13 [Turn over For Examiner's Use (iii) Each 5 kg bag of flour has a volume of 5500 cm3. Calculate the average density of the bag of flour. State your answer in g / cm3. State the formula that you use and show your working. formula working g / cm3 [2] (b) The store has a fire alarm, which detects an increase in temperature. The fire alarm circuit has a resistor R, a thermistor and a buzzer connected to the battery shown in Fig. 6.2. R Fig. 6.2 Explain what happens to the current in the fire alarm circuit when the temperature increases. [3]

18 © UCLES 2013 0654/31/M/J/13 For Examiner's Use (c) Three boys, A, B and C, walk together from their school to a store. They stay at the store for a few minutes and then return to school. When they leave the store, • one boy walks back to school at a steady pace, • one boy walks back to school at a slower steady pace, • one boy slows down gradually as he walks back to school. The graph in Fig. 6.3 shows how their speeds vary with time. 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0 0 100 200 300 400 500 time / s speed / m per s 600 700 800 900 1000 boys boys A, , B and and C boy boy B boy boy A boy boy C boy A boy C boy B boys A, B and C Fig. 6.3 (i) Calculate the distance of the store from the school. Show your working. [2] (ii) For how many seconds do the boys stay in the store? s [1] (iii) Which boy slowed down on his way back to school? Explain your answer. [1]

19 © UCLES 2013 0654/31/M/J/13 [Turn over For Examiner's Use 7 The metal vanadium is mixed with iron and carbon to make vanadium steel. (a) (i) Vanadium metal may be obtained by reducing vanadium oxide with magnesium. Suggest the word chemical equation for this reaction. [1] (ii) Vanadium is a transition metal and magnesium is in Group 2 of the Periodic Table. Suggest two differences in properties between vanadium and magnesium. 1 2 [2]

20 © UCLES 2013 0654/31/M/J/13 For Examiner's Use (b) Sulfuric acid is made in industry by the Contact Process. Fig. 7.1 shows a simplified flow diagram of part of the Contact Process. sulfur dioxide and oxygen sulfur trioxide many small pieces of vanadium oxide reaction vessel Fig. 7.1 A mixture of the gases sulfur dioxide and oxygen passes over the surface of solid vanadium oxide inside the reaction vessel. The unbalanced equation for the reaction that occurs in the reaction vessel is shown below. Balance the equation and explain why it does not contain the formula of vanadium oxide. SO2 + O2 SO3 explanation [2]

21 © UCLES 2013 0654/31/M/J/13 [Turn over For Examiner's Use (c) 1.00 kg of a sample of concentrated sulfuric acid contains 98% by mass of H2SO4 molecules. Calculate the number of moles of H2SO4 molecules in 1.00 kg of this sample of concentrated sulfuric acid. Show your working. [3]

22 © UCLES 2013 0654/31/M/J/13 For Examiner's Use 8 The addition of a harmful substance to the environment is called pollution. Three examples of pollution caused by human activities are • acid rain, • fertilisers entering rivers and lakes, • the release of too much carbon dioxide into the atmosphere. (a) Describe how acid rain is caused. [2] (b) Explain what happens in a lake after large quantities of fertilisers are washed into it. [4] (c) Explain how cutting down forests can result in an increase in the carbon dioxide concentration in the atmosphere. [2]

23 © UCLES 2013 0654/31/M/J/13 [Turn over For Examiner's Use 9 (a) Fig. 9.1 shows a mobile phone (cell phone) and battery charger. Input 220 V Output 5 V Fig. 9.1 A transformer inside the battery charger reduces the 220 V mains supply to the 5 V used to charge the mobile phone battery. The transformer has 40 turns on its secondary coil. Calculate the number of turns on the primary coil of the transformer in the battery charger. State the formula that you use and show your working. formula working [2] (b) Describe and explain how transformers are used in the large scale transmission of electricity. [3]

24 © UCLES 2013 0654/31/M/J/13 For Examiner's Use 10 (a) Fig. 10.1 shows apparatus a student used to investigate the reaction between a white powder and dilute hydrochloric acid. The student predicted which gas would be given off in her experiment and chose to test the gas using limewater. side-arm test-tube dilute hydrochloric acid white powder limewater Fig. 10.1 State the gas that the student predicted would be given off. Explain your answer. name of gas explanation [2]

25 © UCLES 2013 0654/31/M/J/13 [Turn over Question 10 continues over the page.

26 © UCLES 2013 0654/31/M/J/13 For Examiner's Use (b) The student investigated the temperature change when sodium hydrogencarbonate was added to excess dilute hydrochloric acid. Fig. 10.2 shows the apparatus she used. temperature sensor insulated beaker reaction mixture Fig. 10.2 Temperature measurements were displayed on the computer screen as a graph of temperature against time. This graph is shown in Fig. 10.3. 0 1 2 3 4 time / min 5 6 7 8 20 15 10 5 0 temperature / °C start of start of experiment experiment start of experiment Fig. 10.3 (i) On the graph, mark with an X the point where sodium hydrogencarbonate was added to the dilute hydrochloric acid. [1] (ii) Calculate the temperature change shown in Fig. 10.3 that occurred during the reaction. [2]

27 © UCLES 2013 0654/31/M/J/13 [Turn over For Examiner's Use (iii) Use the results shown in Fig. 10.3 to explain, in terms of chemical energy and heat energy, the energy transformation that occurred during the reaction. [2] (c) The student’s teacher then set up the apparatus shown in Fig. 10.4 in a fume cupboard. neutral full range indicator solution (Universal Indicator) strong heat mixture of solid reactants Fig. 10.4 The teacher heated the mixture of reactants. A gas was given off which did not change the colour of the indicator. The teacher told the student • that the gas was an oxide of carbon, • that the relative formula mass of the gas molecules was 28. (i) State and explain why the observation involving the indicator shows that the gas produced was not carbon dioxide. [2] (ii) Use the value of the relative formula mass to deduce the chemical formula of the gas produced in this experiment. [2]

28 © UCLES 2013 0654/31/M/J/13 For Examiner's Use 11 Fig. 11.1 shows the human gas exchange system. Fig. 11.1 (a) Use label lines to label each of these structures on Fig. 11.1. trachea bronchus larynx [3] (b) Gas exchange takes place across the surface of the alveoli in the lungs. List three features of alveoli that help gas exchange to take place quickly. 1 2 3 [3]

29 © UCLES 2013 0654/31/M/J/13 [Turn over For Examiner's Use (c) The gas exchange system is protected from pathogens and harmful substances by a tissue, containing goblet cells and ciliated cells, that lines the nose, trachea and bronchi. Fig. 11.2 shows part of this tissue inside the nose. goblet cell to opening of nostril to lungs thin layer of mucus cilia Fig. 11.2 Describe how the tissue shown in Fig. 11.2 helps to stop harmful substances getting into the lungs. [2]

30 © UCLES 2013 0654/31/M/J/13 For Examiner's Use (d) An experiment was carried out to find out how passive smoking affects the activity of the goblet cells and cilia. Six people sat in a closed room. On day 1, they breathed normal, clean air. On day 2, they breathed air containing cigarette smoke. After one hour, an aerosol containing a radioactive isotope of technetium, 99Tc, was sprayed into each person’s nose. This isotope produces gamma radiation. The researchers measured the radioactivity in each person's nostrils for 40 minutes. This was done on both days. The faster the cilia and goblet cells were working, the faster the 99Tc was removed from the nose. Table 11.1 shows the results. Table 11.1 percentage of radioactivity remaining after 40 minutes person day 1 after breathing clean air day 2 after breathing air containing cigarette smoke 1 65 26 2 84 49 3 67 96 4 23 51 5 40 91 6 78 24 (i) Suggest why the researchers used a source that emits gamma radiation, rather than one that emits alpha radiation. [2] (ii) Which three persons’ results showed that breathing air containing cigarette smoke slowed down the rate at which their cilia and goblet cells worked? [1]

31 © UCLES 2013 0654/31/M/J/13 [Turn over For Examiner's Use (iii) Suggest how exposure to cigarette smoke could affect the health of these three people. [4]

32 © UCLES 2013 0654/31/M/J/13 For Examiner's Use 12 (a) Electromagnetic waves are transverse waves. Draw labelled diagrams to explain the difference between a transverse wave and a longitudinal wave. [3] (b) Fig. 12.1 shows a person using a periscope to look over a wall. wall mirror mirror Fig. 12.1 (i) On Fig. 12.1 draw a ray diagram to explain how the person can see over the wall. [3]

33 © UCLES 2013 0654/31/M/J/13 For Examiner's Use (ii) An image formed in a plane mirror is called a virtual image. Explain the meaning of the term virtual image. [1] (c) Fig. 12.2 shows a lens being used to observe an object O. The focal length of the lens is 3.0 cm. The diagram is drawn full scale. lens lens lens O Fig. 12.2 (i) On Fig. 12.2 draw two rays from the top of the object O that meet at the image. Label the image X. [3] (ii) Measure the height of the object O and the height of the image X. object height image height [1] (iii) Calculate the magnification. Show your working. [2]

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36 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. University of 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. © UCLES 2013 0654/31/M/J/13 Group 140 Ce Cerium 58 141 Pr Praseodymium 59 144 Nd Neodymium 60 Pm Promethium 61 150 Sm Samarium 62 152 Eu Europium 63 157 Gd Gadolinium 64 159 Tb Terbium 65 162 Dy Dysprosium 66 165 Ho Holmium 67 167 Er Erbium 68 169 Tm Thulium 69 173 Yb Ytterbium 70 175 Lu Lutetium 71 232 Th Thorium 90 Pa Protactinium 91 238 U Uranium 92 Np Neptunium 93 Pu Plutonium 94 Am Americium 95 Cm Curium 96 Bk Berkelium 97 Cf Californium 98 Es Einsteinium 99 Fm Fermium 100 Md Mendelevium 101 No Nobelium 102 Lr Lawrencium 103 1 H Hydrogen 1 7 Li Lithium 3 23 Na Sodium 11 24 Mg Magnesium 12 40 Ca Calcium 20 45 Sc Scandium 21 48 Ti Titanium 22 51 V Vanadium 23 52 Cr Chromium 24 55 Mn Manganese 25 56 Fe Iron 26 59 Co Cobalt 27 59 Ni Nickel 28 64 Cu Copper 29 65 Zn Zinc 30 70 Ga Gallium 31 27 Al Aluminium 13 11 B Boron 5 12 C Carbon 6 14 N Nitrogen 7 16 O Oxygen 8 19 F Fluorine 9 28 Si Silicon 14 31 P Phosphorus 15 32 S Sulfur 16 35.5 Cl Chlorine 17 40 Ar Argon 18 20 Ne Neon 10 4 He Helium 2 73 Ge Germanium 32 75 As Arsenic 33 79 Se Selenium 34 80 Br Bromine 35 84 Kr Krypton 36 39 K Potassium 19 88 Sr Strontium 38 89 Y Yttrium 39 91 Zr Zirconium 40 93 Nb Niobium 41 96 Mo Molybdenum 42 Tc Technetium 43 101 Ru Ruthenium 44 103 Rh Rhodium 45 106 Pd Palladium 46 108 Ag Silver 47 112 Cd Cadmium 48 115 In Indium 49 119 Sn Tin 50 122 Sb Antimony 51 128 Te Tellurium 52 127 I Iodine 53 131 Xe Xenon 54 137 Ba Barium 56 139 La Lanthanum 57 * 178 Hf Hafnium 72 181 Ta Tantalum 73 184 W Tungsten 74 186 Re Rhenium 75 190 Os Osmium 76 192 Ir Iridium 77 195 Pt Platinum 78 197 Au Gold 79 201 Hg Mercury 80 204 Tl Thallium 81 207 Pb Lead 82 209 Bi Bismuth 83 Po Polonium 84 At Astatine 85 Rn Radon 86 Fr Francium 87 227 Ac Actinium 89 9 Be Beryllium 4 I II III IV V VI VII 0 85 Rb Rubidium 37 133 Cs Caesium 55 226 Ra Radium 88 The volume of one mole of any gas is 24 dm3 at room temperature and pressure (r.t.p.). a X b a = relative atomic mass X = atomic symbol b = proton (atomic) number Key *58-71 Lanthanoid series 90-103 Actinoid series DATA SHEET The Periodic Table of the Elements

CAMBRIDGE INTERNATIONAL EXAMINATIONS International General Certificate of Secondary Education MARK SCHEME for the May/June 2013 series 0654 CO-ORDINATED SCIENCES 0654/31 Paper 3 (Extended Theory), maximum raw mark 120 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 May/June 2013 series for most IGCSE, GCE Advanced Level and Advanced Subsidiary Level components and some Ordinary Level components.

Page 2 Mark Scheme Syllabus Paper IGCSE – May/June 2013 0654 31 © Cambridge International Examinations 2013 1 (a) (i) (A) sum of protons and neutrons is greatest / nucleon number is sum of protons and neutrons / most protons and neutrons ; [1] (ii) A and D ; proton number 2 shows helium ; (isotopes) have same number of protons but different, numbers of neutrons / (atomic) mass ; [max 2] (b) (i) atoms share electrons ; electron pair (is shared) ; electron pair lies between nuclei / shields nuclear repulsion ; [max 2] (ii) helium (atoms) inert / stable / unreactive / do not (need to) bond ; reference to complete (outer) shell ; [max 1] (c) pop (test) indicates hydrogen (given off) / hydrogen is given off ; zinc displaces hydrogen / reacts with HCl to produce hydrogen / silver does not react with HCl to produce hydrogen ; zinc more reactive than hydrogen ; silver less reactive than hydrogen (so no reaction) ; [max 3] [Total: 9] 2 (a) (i) (distance =) speed × time ; = 1600 × 0.2 / 2 = 160 m ; [2] (ii) (frequency =) velocity / wavelength, or velocity = frequency × wavelength ; frequency = 1600 / 0.25 = 6400 Hz ; [2] (b) less fossil fuels used up / fossil fuels are conserved ; no emissions causing acid rain ; no CO2 emissions / greenhouse gases ; (reduced) greenhouse effect / global warming / consequences e.g. climate change / changed weather patterns etc.; [max 2] (c) (i) sea water ; [1] (ii) evaporation ; [1] [Total: 8]

Page 3 Mark Scheme Syllabus Paper IGCSE – May/June 2013 0654 31 © Cambridge International Examinations 2013 3 (a) (i) anther, filament ; [1] (ii) ovary wall, ovule, stigma ; [1] (iii) insect gets nectar (from nectary) / insect goes to nectary ; anthers / stigma, inside petals ; insect has to brush against them ; pollen picked up from anthers ; pollen deposited on stigma ; [max 3] (b) (i) ‘named’ fruit drawn with feature to allow wind dispersal (e.g. wings, parachute) ; annotation comments on this feature ; [2] (ii) spread to, new / larger, areas / reduce competition ; [1] [Total: 8] 4 (a) chain of three carbon atoms joined by single bonds ; eight hydrogen atoms correctly bonded to carbon ; i.e. ;; [max 2] (b) (i) decreases (from D to A) ; [1] (ii) (boiling range) / boiling point, is lower at B than C ; (average) molecular size is lower at B / the smaller the molecular size the lower the boiling point.; (mean) intermolecular attraction lower at B / the lower the intermolecular force the lower the boiling point.; so less (heat) energy needed to separate molecules / boil the mixture ; intermolecular attraction is lower for smaller molecules ; [max 3] (c) (i) too reactive / elements unstable / they would react / compounds (much) more stable ; [1] (ii) sodium atoms lose one electron / outer shell electron / become 2.8 ; chlorine atoms gain one electron / complete their outer shell / become 2.8.8 ; [2] (iii) particles shown as positively and negatively charged ; ions shown alternating in ratio 1:1 ; shape shown as square / cube ; [3] [Total: 12]

Page 4 Mark Scheme Syllabus Paper IGCSE – May/June 2013 0654 31 © Cambridge International Examinations 2013 5 (a) (i) calcium ; [1] (ii) water / H2O ; [1] (iii) has more calcium ; for, teeth / bones ; OR has more protein ; for making new, proteins / cells / enzymes / growth / repair of tissue ; OR if specifically in the context of famine conditions or nutrition of infants has more fat ; for survival of adults in famine conditions / for infant growth ; [max 2] (iv) has less fat / use of data ; reference to risk of, obesity / heart disease ; [2] (v) can be absorbed as it is / idea that it consists of particles small enough (to be absorbed) ; [1] (b) (i) to speed up the process ; reference to enzymes ; idea of enzymes working faster at this temperature ; [max 2] (ii) slows / stops enzymes working / to keep it fresh / the idea that enzymes stop working (so well) ; [1] (iii) acid produced ; [1] [Total: 11]

Page 5 Mark Scheme Syllabus Paper IGCSE – May/June 2013 0654 31 © Cambridge International Examinations 2013 6 (a) (i) (work =) force × distance ; X’s work is 120 J and Y’s work is 100 J (so X does more work) ; [2] (ii) worker X (no mark) power = work ÷ time, or power α 1 ÷ time, or power is, rate of doing work ÷ work done per second, or how quickly work is done, so worker X uses more power ; [1] (iii) (density =) mass / volume ; = 5000 / 5500 = 0.91 (g / cm3) ; [2] (b) resistance of thermistor goes down ; current goes up ; reference to V = IR ; (supply) voltage is constant ; [max 3] (c) (i) 1.2 × 240 (with or without units) / use of (distance =) speed × time, or area under graph ; 288 m ; [2] (ii) 240 (s) ; [1] (iii) boy C (no mark) (line on) graph goes down (so speed was changing) / owtte / use of data ; [1] [Total: 12] 7 (a) (i) vanadium oxide + magnesium → vanadium + magnesium oxide ; [1] (ii) vanadium has higher density ; vanadium has higher melting point ; vanadium can act as catalyst ; vanadium forms coloured compounds ; [max 2] (b) 2SO2 + O2 → 2SO3 ; vanadium oxide is a catalyst / is not (permanently) changed ; [2] (c) Mr of H2SO4 = 98 ; 98% of 1 kg = 0.98 (kg) = 980 (g) ; number of moles = mass ÷ molar mass 980 ÷ 98 = 10 (moles) ; [3] [Total: 8]

Page 6 Mark Scheme Syllabus Paper IGCSE – May/June 2013 0654 31 © Cambridge International Examinations 2013 8 (a) combustion / burning, of (fossil) fuels ; sulfur dioxide produced ; (sulfur dioxide), reacts with / dissolves in / mixes with, water (in atmosphere) ; [max 2] (b) eutrophication ; increased growth of algae / surface plants ; blocks light to plants (deeper down) ; algae / plants die ; bacteria feed on them / population increases ; bacteria etc. use oxygen ; removal of oxygen kills fish ; [max 4] (c) less photosynthesis ; so less carbon dioxide removed ; OR trees burned ; producing carbon dioxide ; [max 2] [Total: 8] 9 (a) (i) V1 / V2 = N1 / N2 ; N1 = 220 × 40 / 5 = 1760 (turns) ; [2] (b) transformers increase voltage at power station ; to reduce current in cables ; to reduce energy losses ; transformers decrease voltage at point of use ; correct voltage for safe use in domestic appliances / owtte ; [max 3] [Total: 5]

Page 7 Mark Scheme Syllabus Paper IGCSE – May/June 2013 0654 31 © Cambridge International Examinations 2013 10 (a) carbon dioxide / CO2 ; limewater turns cloudy etc.(with carbon dioxide) / limewater reacts with carbon dioxide / limewater is the test reagent for CO2 ; [2] (b) (i) X shown clearly on graph at 2 min ; [1] (ii) decrease of / or negative value indicated ; 7 °C ; [2] (iii) (reaction is) endothermic / heat energy is, removed from mixture / taken in ; thermal / heat / kinetic energy converted to (internal) chemical energy ; products have more chemical energy than reactant / owtte ; [max 2] (c) (i) carbon dioxide would react with the water ; producing an acidic solution / lowering pH / CO2 is an acidic gas ; which would change the indicator colour / turn indicator orange / red ; [max 2] (ii) formula is CO ; logical statement(s) ; e.g. (must be at least one O, so) 28 – 16 = 12 (which can only be one C) OR (both carbon oxides have only one carbon atom so) 28 – 12 = 16 (so only one oxygen also) [max 2] [Total: 11]

Page 8 Mark Scheme Syllabus Paper IGCSE – May/June 2013 0654 31 © Cambridge International Examinations 2013 11 (a) [3] (b) large surface area ; reference to moist surface / owtte ; good blood supply ; thin wall ; [max 3] (c) goblet cell produces mucus ; mucus traps, bacteria / pathogens / dust / particles ; cilia sweep mucus, upwards / away from lungs / to throat ; [max 2] (d) (i) alpha would be too ionising ; reference to specific harm done by radiation – mutation / DNA damaged / cells killed / burns / cancer ; [2] (ii) (people) 3, 4 and 5 ; [1] (iii) reference to bronchitis / inflammation in airways ; (because) more mucus produced / damaged cilia unable to remove mucus (as efficiently) ; in which bacteria breed ; reference to emphysema / breakdown / destruction of alveolar walls ; so gas exchange less efficient / difficult to get enough oxygen ; reference to tar reduces efficiency of gaseous exchange ; carbon monoxide, inhibits uptake / takes the place of, oxygen by red blood cells ; reference to lung / other relevant cancer / reference to other specific disease related to smoking ; [max 4] [Total: 15] larynx trachea bronchus

Page 9 Mark Scheme Syllabus Paper IGCSE – May/June 2013 0654 31 © Cambridge International Examinations 2013 12 (a) transverse – vibration at right angles to motion ; electromagnetic waves do not need a medium ; e.g. vibration
~~~~~~  direction of wave motion longitudinal – vibration in direction of motion ; series of compressions and rarefactions ; e.g. vibration  III I I III I  direction of wave motion [max 3] (b) (i) accuracy ; straight lines ; arrow(s) in right direction ; [3] (ii) one which cannot be projected on to a screen etc. ; [1] (c) (i) any two of: one ray from top of object parallel with principal axis, then through principal focus ; one ray from top of object through optical centre of lens ; one ray from top of object through principal focus on object side of lens then parallel with principal axis ; (for 2 marks) image drawn and labelled in the correct place ; [max 3] (ii) object height = 2.0 cm, image height = 2.8 to 3.4 cm ; [1] (iii) magnification = height of image / height of object ; 3.1 / 2.0 = 1.6 ; [2] [Total: 13]