Cambridge IGCSE Sciences - Co-ordinated (Double) 0654 — 2013 May/June Paper 2 · Variant 1

This document consists of 31 printed pages and 1 blank page. IB13 06_0654_21/3RP © UCLES 2013 [Turn over *3463335646* UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS International General Certificate of Secondary Education CO-ORDINATED SCIENCES 0654/21 Paper 2 (Core) 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 32. 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 0654/21/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 1 0 1 B 8 8 8 C 1 1 1 D 15 16 15 (i) Explain which one of the atoms, A, B, C or D, has a nucleon number (mass number) of 16. atom explanation [2] (ii) Explain which pair of atoms chosen from A, B, C and D are isotopes of hydrogen. atom and atom explanation [2] (iii) Use the information in Table 1.1 to explain why atoms are electrically neutral. [2]

3 © UCLES 2013 0654/21/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) Hydrogen is usually described as a non-metal. Name the type of chemical bond joining the atoms in a hydrogen molecule. [1] (ii) Suggest why helium exists as uncombined atoms. [1] (iii) State one use of helium. [1]

4 © UCLES 2013 0654/21/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 Fig. 1.2 [2]

5 © UCLES 2013 0654/21/M/J/13 [Turn over For Examiner's Use 2 (a) A fishing boat is floating on the sea. A fisherman drops a heavy anchor from the boat. The anchor accelerates as it falls through the water. Name the downward force which makes the anchor accelerate. [1] (b) A 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. Calculate the distance of the shoal of fish below the boat. State the formula that you use and show your working. formula working m [2]

6 © UCLES 2013 0654/21/M/J/13 For Examiner's Use (c) (i) Water waves are a renewable energy resource. Outline two advantages of using renewable energy resources. 1 2 [2] (ii) Fig. 2.2 shows how water waves can be used to produce electricity. waves water movement causes air to move in and out of the air chamber waves make water rise and fall in air chamber air chamber turbine generator Fig. 2.2 Using the information in Fig. 2.2, describe two of the energy transfers that are involved in changing the kinetic energy of the waves into electrical energy. [2]

7 © UCLES 2013 0654/21/M/J/13 [Turn over For Examiner's Use (d) Fig. 2.3 shows an iceberg floating in the sea. water vapour in air air sea water ice Fig. 2.3 (i) Which material named on Fig. 2.3 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] (iii) Name the process by which water changes to ice. [1]

8 © UCLES 2013 0654/21/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 Fig. 3.1 (a) Draw lines to link each structure to its function. petal structure anther stigma sepal protects the flower when it is a bud function receives pollen produces pollen attracts insects to the flower [3] (b) After pollination, the ovule inside the ovary may be fertilised. The ovary develops into a fruit, and the ovule develops into a seed. List three factors that all seeds need for germination. 1 2 3 [3]

9 © UCLES 2013 0654/21/M/J/13 [Turn over For Examiner's Use (c) Plants use flowers for sexual reproduction. State two ways in which asexual reproduction differs from sexual reproduction. 1 2 [2]

10 © UCLES 2013 0654/21/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 hydrocarbons known as alkanes. (i) Draw the structure of the alkane molecule that contains two carbon atoms. Use short lines to represent covalent bonds. [2] (ii) Name the alkane that is the main constituent of natural gas. [1] (iii) Fig. 4.1 shows the structure of a hydrocarbon molecule. C C C C H H H H H H H H Fig. 4.1 Describe what is observed when this hydrocarbon is shaken with a solution of bromine. [1]

11 © UCLES 2013 0654/21/M/J/13 [Turn over For Examiner's Use (b) When petroleum is refined, it is separated into fractions. Fig. 4.2 shows a simplified diagram of apparatus that is used to refine petroleum. hot petroleum refinery gas diesel oil (gas oil) Fig. 4.2 (i) State the full name of the process shown in Fig. 4.2. [1] (ii) Refinery gas and diesel oil are used as fuels. Name the two compounds that are formed when alkanes in these fuels undergo complete combustion. and [2] (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 element sodium is not found in the Earth’s crust. [1] (ii) When a piece of sodium is placed into a container of chlorine gas, sodium and chlorine atoms are changed into electrically charged atoms known as ions. Describe briefly what happens when sodium atoms and chlorine atoms are changed into ions. [2]

12 © UCLES 2013 0654/21/M/J/13 For Examiner's Use (iii) Explain briefly why the sodium ions and chloride ions bond together in sodium chloride. [2]

13 © UCLES 2013 0654/21/M/J/13 [Turn over For Examiner's Use 5 Milk is a liquid produced by cows and other mammals, on which they feed their young. Table 5.1 shows the mass of some of the substances in 100 g samples of milk from two mammals. Table 5.1 substance cow’s milk water-buffalo’s milk protein / g 3.2 4.5 fat / g 3.9 8.0 carbohydrate / g 4.8 4.9 calcium / mg 120 195 (a) Which substance shown in Table 5.1 is present in the samples of milk in the smallest quantity? [1] (b) Suggest which substance, not shown in Table 5.1, is present in the samples of milk in the largest quantity. [1] (c) Explain why both cow’s milk and water-buffalo’s milk produce a violet colour when tested with biuret solution. [1] (d) Predict the colour you would see if you added iodine solution to cow’s milk. Explain your answer. colour explanation [2] (e) List the components of milk, shown in Table 5.1, that provide energy. [1]

14 © UCLES 2013 0654/21/M/J/13 For Examiner's Use (f) Explain one way in which drinking water-buffalo’s milk might be better for a person’s health than drinking cow’s milk. [2] (g) State and explain which substance in Table 5.1 does not need to be digested in the human alimentary canal. [2]

15 © UCLES 2013 0654/21/M/J/13 [Turn over 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, 0.5 m apart. The lowest shelf is 0.5 m from the floor. Fig. 6.1 shows the two workers. 0.5 m 0.5 m 0.5 m 0.5 m 0.5 m shelf 5 shelf 4 shelf 3 shelf 2 shelf 1 worker Y worker X Fig. 6.1 (i) Describe the energy change when a bag of flour falls off the shelf. energy is changed into energy. [2] (ii) What happens to the energy of the flour as it hits the floor? [1] (iii) Worker X lifts a bag of flour onto shelf 2. Worker Y lifts a bag of flour onto shelf 4. Which worker has done more work? Explain your answer. [1] (iv) State the unit in which work and energy are measured. [1]

16 © UCLES 2013 0654/21/M/J/13 For Examiner's Use (v) 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]

17 © UCLES 2013 0654/21/M/J/13 [Turn over For Examiner's Use (b) 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. 6.2 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. 6.2 (i) Calculate the distance of the store from the school. Show your working. m [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? State a reason for your answer. boy because [2]

18 © UCLES 2013 0654/21/M/J/13 For Examiner's Use 7 The metal vanadium is mixed with iron and carbon to make vanadium steel. (a) (i) State the general name for mixtures containing metals. [1] (ii) Vanadium steel is used to make tools such as spanners (wrenches) and turbine blades in jet engines. VANADIUM STEEL VANADIUM STEEL Suggest one advantage of vanadium steel compared to mild steel. [1] (iii) Vanadium metal may be obtained by reacting vanadium oxide with magnesium. The equation for the reaction is vanadium oxide + magnesium vanadium + magnesium oxide Explain which substance is reduced in this reaction. substance explanation [2] (iv) Vanadium is a transition metal and magnesium is in Group 2 of the Periodic Table. Suggest two properties of vanadium which are typical of transition metals and which are not possessed by magnesium. 1 2 [2]

19 © UCLES 2013 0654/21/M/J/13 [Turn over For Examiner's Use (b) Vanadium oxide is an important catalyst which is used in making sulfuric acid in the chemical industry. Fig. 7.1 shows a simplified diagram of the reaction vessel which contains vanadium oxide. sulfur dioxide and oxygen sulfur trioxide many small pieces of vanadium oxide reaction vessel Fig. 7.1 In this reaction vessel, sulfur dioxide and oxygen react together on the surface of vanadium oxide. (i) State what is meant by the term catalyst. [2] (ii) Use the information in Fig. 7.1 to suggest the word chemical equation for the reaction between sulfur dioxide and oxygen. [1] (iii) Explain why it is very important that none of the gas mixture involved in making sulfuric acid escapes into the air inside the factory. [2]

20 © UCLES 2013 0654/21/M/J/13 For Examiner's Use 8 Fig. 8.1 shows some organisms that live in and around a pond. heron water snails yellow water lily fish fish not to scale Fig. 8.1 (a) Herons eat fish. Water snails eat water plants, such as yellow water lilies. Tick all the boxes that correctly describe each organism. producer consumer carnivore herbivore heron water snail yellow water lily [3] (b) The addition of a harmful substance to the environment is called pollution. Two examples of pollution caused by human activities are • untreated sewage entering a pond, • the release of methane into the atmosphere. (i) Explain why untreated sewage entering a pond may cause fish to die. [2]

21 © UCLES 2013 0654/21/M/J/13 [Turn over For Examiner's Use (ii) Methane is produced by bacteria and other decomposers breaking down organic waste material in rubbish dumps. Describe how air pollution by methane can harm the environment. [2]

22 © UCLES 2013 0654/21/M/J/13 For Examiner's Use 9 (a) Complete the following sentences choosing from the terms below. Each term may be used once, more than once or not at all. current parallel potential difference resistance series watt A flow of electric charge is called a . An ammeter is used to measure . A drives a current between two points in a circuit. [3] (b) A student investigated how a change in potential difference across a lamp affected the current flowing through the lamp. She used wires to connect the components shown in Fig. 9.1 to make a circuit. 1 2 3 0 V A + – + – 0.4 0.6 0.8 1.0 0.2 0 Fig. 9.1 (i) Using the correct circuit symbols, draw a diagram to show the circuit she used. [4]

23 © UCLES 2013 0654/21/M/J/13 [Turn over For Examiner's Use (ii) The student measured the current passing through a wire when a potential difference was applied across it. Calculate the resistance of the wire when a potential difference of 0.3 V is applied and the current measured is 0.5 A. State the formula that you use and show your working. formula working Ω [2] (c) Electricity is often transmitted through overhead power cables hung from pylons. If these cables are put up on a hot summer day, they are hung loosely from the pylons as shown in Fig. 9.2. Fig. 9.2 Suggest why the cables are hung loosely. [2]

24 © UCLES 2013 0654/21/M/J/13 For Examiner's Use 10 (a) Sodium hydrogencarbonate, NaHCO3, is a white solid compound. State the number of different elements that are shown combined in the formula, NaHCO3. [1] (b) Fig. 10.1 shows apparatus a student used to investigate the reaction between sodium hydrogencarbonate and dilute hydrochloric acid. side-arm test-tube dilute hydrochloric acid sodium hydrogencarbonate full range indicator solution (Universal Indicator) Fig. 10.1 The student observed that the indicator changed colour from green to orange. Explain this observation. [2]

25 © UCLES 2013 0654/21/M/J/13 [Turn over For Examiner's Use (c) The student investigated the temperature change when sodium hydrogencarbonate was added to excess dilute hydrochloric acid. Fig. 10.2 shows the apparatus she used. dilute hydrochloric acid sodium hydrogencarbonate thermometer Fig. 10.2 Table 10.1 shows the temperature measurements the student made. Table 10.1 temperature of the acid before the reaction / °C 19.0 temperature of the reaction mixture after reaction / °C 12.0 (i) Calculate the temperature change that occurred during the reaction. °C [2] (ii) State the term that is used to describe chemical reactions that cause this type of temperature change. [1] (d) A soluble calcium compound can be made by reacting lemon juice with finely powdered egg shells, which are made mainly of calcium carbonate. Lemon juice contains a relatively low concentration of acid. Suggest why the egg shells are used in the form of a fine powder. [2]

26 © UCLES 2013 0654/21/M/J/13 For Examiner's Use 11 Fig. 11.1 shows the human gas exchange system. A B C Fig. 11.1 (a) Name structures A, B and C. A B C [3] (b) Table 11.1 shows the differences in the composition of inspired and expired air. Table 11.1 gas percentage in inspired air percentage in expired air nitrogen 78 oxygen 21 17 carbon dioxide 0.04 4 noble gases 1 (i) Complete Table 11.1. [1] (ii) Name one noble gas that is present in air. [1]

27 © UCLES 2013 0654/21/M/J/13 [Turn over For Examiner's Use (iii) Explain why the air that we breathe out (expired air) contains less oxygen and more carbon dioxide than the air we breathe in. [2] (iv) Describe how you could show that expired air contains more carbon dioxide than inspired air. You can use a diagram if it helps your answer. [3]

28 © UCLES 2013 0654/21/M/J/13 For Examiner's Use (c) An athlete exercised on a treadmill. The treadmill measured her power output, in watts. The faster she ran, the greater her power output. (i) Explain why the athlete’s power output was greater when she ran faster. [2]

29 © UCLES 2013 0654/21/M/J/13 [Turn over For Examiner's Use (ii) The athlete was connected to a machine that measured the rate and depth of her breathing. Fig. 11.2 shows how her depth of breathing changed when she ran with different power outputs. 0 50 100 150 200 250 3 2 1 0 power output when running / W volume of air breathed in with each breath / dm3 Fig. 11.2 Describe how the athlete’s depth of breathing changed when she ran with a greater power output. [2] (iii) State one other way in which her breathing would change when she ran with a greater power output. [1]

30 © UCLES 2013 0654/21/M/J/13 For Examiner's Use 12 (a) Light energy travels to the Earth from the Sun. State whether this transfer of energy is by conduction, convection or radiation. Explain your answer. [2] (b) Light waves may change their direction when they travel from air into glass. Name this effect. [1] (c) When an object is viewed in a plane mirror, an image can be seen. Tick the boxes next to the three characteristics which correctly describe the image. same way up as object upside down compared to object same size as object smaller than object larger than object laterally inverted not laterally inverted [2]

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32 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 0654/21/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 0654/21 Paper 2 (Core 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 21 © Cambridge International Examinations 2013 1 (a) (i) B ; sum of protons and neutrons is 16 ; [2] (ii) A and C ; proton number 1 shows hydrogen (so it has to be these two) ; (isotopes) have same number of protons but different numbers of neutrons ; [max 2] (iii) numbers of protons and electrons are the same ; protons positive electrons negative ; charges (of protons and electrons) cancel ; [max 2] (b) (i) covalent ; [1] (ii) helium is inert / unreactive / stable / no need to bond (to become stable) ; reference to complete outer shell ; [max 1] (iii) airships / balloons / other correct ; [1] (c) pop (test) indicates hydrogen (given off) ; zinc reacts to displace hydrogen ; zinc more reactive than hydrogen ; [max 2] [Total: 11] 2 (a) gravity ; [1] (b) (distance =) speed × time ; = 1600 × 0.2 / 2 = 160 (m) ; [2] (c) (i) less fossil fuels used up ; reduce global warming ; no CO2 emissions ; no acid rain emissions ; will not run out; [max 2] (ii) transfer of KE to PE as water moves up chamber ; transfer of KE to air inside chamber ; transfer of KE of air to KE of (rotation of) turbine ; transfer of KE of turbine to KE of generator ; transfer of KE of generator to electrical energy ; [max 2]

Page 3 Mark Scheme Syllabus Paper IGCSE – May/June 2013 0654 21 © Cambridge International Examinations 2013 (d) (i) sea water ; [1] (ii) evaporation ; [1] (iii) freezing / solidification ; [1] [Total: 10] 3 (a) all four correct for 3 marks two or three correct for 2 marks one correct for 1 mark ;;; [3] (b) water ; suitable temperature / warmth ; air / oxygen [3] (c) no gametes ; no fertilisation ; no zygote ; no (genetic) variation ; only one parent / plant ; no meiosis ; [max 2] [Total: 8] petal structure anther stigma sepal protects the flower when it is a bud function receives pollen produces pollen attracts insects to the flower

Page 4 Mark Scheme Syllabus Paper IGCSE – May/June 2013 0654 21 © Cambridge International Examinations 2013 4 (a) (i) chain of two carbon atoms joined by single bond ; only six hydrogen atoms correctly bonded to carbon ; [2] (ii) methane ; [1] (iii) colour change orange to colourless ; [1] (b) (i) fractional distillation / fractionation; [1] (ii) carbon dioxide; water (ignore vapour) ; [2] (c) (i) too reactive / compounds much more stable ; [1] (ii) electrons are transferred ; both get a full shell; sodium atoms lose (one) electron / outer shell electron / become 2,8 ; chlorine atoms gain (one) electron / complete outer shell / become 2,8,8 ; [max 2] (iii) ions have opposite electrical charges ; opposites attract / (which have a) strong attractive (force) / strong attraction ; [2] [Total: 12] 5 (a) calcium ; [1] (b) water ; [1] (c) they contain protein ; [1] (d) orange / brown / yellow ; it does not contain starch ; [2] (e) protein, fat and carbohydrate ; [1] (f) has more calcium ; for, teeth / bones ; OR has more protein; for making / cells / enzymes; [max 2] (g) calcium ; can be absorbed as it is / it is already small enough to be absorbed ; [2] [Total: 10]

Page 5 Mark Scheme Syllabus Paper IGCSE – May/June 2013 0654 21 © Cambridge International Examinations 2013 6 (a) (i) (gravitational) potential ; kinetic ; [2] (ii) changed into sound / heat ; [1] (iii) worker Y (no mark) same force but bigger distance / work is force × distance and distance is bigger ; [1] (iv) joules ; [1] (v) (density =) mass ÷ volume ; = 5000 / 5500 = 0.91 (g / cm3) ; [2] (b) (i) working and / or use of speed × time ; 288 (m) ; [2] (ii) 240 (s) ; [1] (iii) boy C ; (line on) graph goes down etc. (so speed was changing / decreasing) ; [2] [Total: 12] 7 (a) (i) alloy ; [1] (ii) stronger / harder / better corrosion resistance ; [1] (assume refers to alloy) (iii) vanadium oxide ; (reduction is) removal of oxygen; (allow correct oilrig reference) [2] (iv) high density ; (relatively) high melting point ; can act as catalyst ; forms coloured compounds ; [max 2] (b) (i) substance that changes / increases rate ; but is not itself (permanently) changed ; [2] (reject catalyst oxide does not take part in reaction) (ii) sulfur dioxide + oxygen → sulfur trioxide ; [1] (iii) sulfur dioxide (or sulfur trioxide) is corrosive / harmful / irritant ; reference to corrosion of fabric of factory ; reference to specific damage to humans e.g. damage to respiratory system ; [max 2] [Total: 11]

Page 6 Mark Scheme Syllabus Paper IGCSE – May/June 2013 0654 21 © Cambridge International Examinations 2013 8 (a) producer consumer carnivore herbivore heron √ √ water snail √ √ yellow water lily √ 1 mark per correct row ;;; [3] (b) (i) eutrophication ; increased growth of algae ; reduction of (dissolved) oxygen ; reference to toxins / named toxin ; (ii) reference to greenhouse gas ; traps heat ; global warming ; reference to consequence of global warming (e.g. sea level rise, more extremes of weather, change in habitats of living organisms) ; [max 2] [Total: 7] 9 (a) current ; current ; potential difference ; [3] (b) (i) e.g. at least 3 symbols correct ; all 5 symbols correct ; ammeter in series and voltmeter in parallel ; everything else correct ; [4] (ii) V = IR ; R = 0.3 / 0.5 = 0.6 (Ω) ; [2] (c) metals contract when cold ; cables become too tight / damage pylons ; if put up tight in summer; [max 2] [Total: 11] A V

Page 7 Mark Scheme Syllabus Paper IGCSE – May/June 2013 0654 21 © Cambridge International Examinations 2013 10 (a) 4 ; [1] (b) carbon dioxide ; produces an acidic solution / lowers pH ; [2] (c) (i) decrease ; of 7 (°C) ; [2] (–7 scores both) (ii) endothermic ; [1] (d) powder has large surface area ; powder has higher rate of reaction (with acid) ; which counteracts low rate caused by relatively low acid concentration ; [max 2] [Total: 8] 11 (a) A: larynx ; B: trachea ; C: bronchiole ; [3] (b) (i) gas percentage in inspired air percentage in expired air nitrogen 78 78 oxygen 21 17 carbon dioxide 0.04 4 noble gases 1 1 both required for 1 mark ; [1] (ii) helium / neon / argon / krypton / xenon / radon ; [1] (iii) respiration ; uses oxygen and produces carbon dioxide ; oxygen diffuses into blood (from lungs) and carbon dioxide diffuses from blood (into lungs) ; [max 2] (iv) limewater / hydrogencarbonate indicator ; method bubbles both types of air through the indicator ; reference to comparison of time taken for indicator to change colour ; [3]

Page 8 Mark Scheme Syllabus Paper IGCSE – May/June 2013 0654 21 © Cambridge International Examinations 2013 (c) (i) reference to energy / work ; more energy used / more work done / per unit time ; [2] (ii) increased ; use of comparative figures (e.g. 0.5 dm3 when no power output, 2.8 dm3 at 225 W) ; reference to change of gradient at 50 W ; [max 2] (iii) faster / more breaths per minute ; [1] [Total: 15] 12 (a) radiation ; does not need a medium ; [2] (b) refraction ; [1] (c) same way up as object same size as object laterally inverted [max 2] (3 correct 2 marks, 1 or 2 correct 1 mark) ;; [Total: 5]