Cambridge IGCSE Sciences - Co-ordinated (Double) 0654 — 2014 May/June Paper 2 · Variant 2

This document consists of 28 printed pages. IB14 06_0654_22/7RP © UCLES 2014 [Turn over *1914321836* Cambridge International Examinations Cambridge International General Certificate of Secondary Education CO-ORDINATED SCIENCES 0654/22 Paper 2 (Core) May/June 2014 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 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. A copy of the Periodic Table is printed on page 28. 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 2014 0654/22/M/J/14 1 (a) Select elements from the list below to complete the left hand column in Table 1.1. Each element may be used once, more than once or not at all. aluminium chlorine copper helium potassium sulfur Table 1.1 element use of element filling weather balloons making food containers sterilising drinking water [3] (b) Table 1.2 shows properties of four elements A, B, C and D. Table 1.2 element melting point / °C electrical conductivity reaction with water A –39 high none B –220 very low reacts quickly C –112 very low none D 181 high reacts quickly Use the information in Table 1.2 to suggest which of the elements A, B, C and D could be: (i) non-metals, and [1] (ii) an element in Group 0 of the Periodic Table, [1] (iii) an element in Group I of the Periodic Table. [1]

3 © UCLES 2014 0654/22/M/J/14 [Turn over (c) A student carries out an experiment involving copper chloride solution, using the apparatus shown in Fig. 1.1. bubbles of gas copper chloride solution graphite anode graphite cathode d.c. power supply metallic layer forming on the electrode Fig. 1.1 (i) Name the process shown in Fig. 1.1. [1] (ii) Write a word equation for the overall chemical reaction that occurs during the process shown in Fig. 1.1. + [2]

4 © UCLES 2014 0654/22/M/J/14 2 (a) A skier takes part in a downhill race. He accelerates from rest. After 30 seconds, he reaches a maximum speed of 12 m / s. He continues at this speed for another 10 seconds. The race is then completed and he slows down and stops after a total time of 50 seconds. On the grid, draw a speed / time graph of the motion of the skier. You will need to complete the scale on each axis. s per m speed 0 0 time / s [3]

5 © UCLES 2014 0654/22/M/J/14 [Turn over (b) For 10 seconds, the skier travels at a constant speed of 12 m / s. Calculate the distance travelled by the skier during the 10 seconds. State the formula that you use and show your working. formula working distance = m [2] (c) The skier travels to the top of the slope using a chair lift. (i) Name the type of the energy the chair lift has when it is moving. [1] (ii) Name the type of energy the skier has gained when he reached the top of the slope. [1] (iii) State the name of the unit used to measure energy and give its symbol. unit = symbol = [1]

6 © UCLES 2014 0654/22/M/J/14 3 Fig. 3.1 shows a reflex arc involved in withdrawing the hand from a painful stimulus. painful stimulus response Fig. 3.1 (a) State one of the seven characteristics of living things which is being shown when someone withdraws their hand from a painful stimulus. [1] (b) (i) On the diagram, label the motor (effector) neurone, the relay (connector) neurone and the sensory neurone. [3] (ii) Which of these neurones is entirely inside the central nervous system? [1] (iii) Explain the advantage of having the reflex arc going through the central nervous system, instead of having the receptor connected directly to the muscle. [1] (c) In another response, a person sees a sharp object coming towards their hand, and the person moves their hand away to avoid the object. Describe how this type of response is different from a simple reflex action. [2]

7 © UCLES 2014 0654/22/M/J/14 [Turn over (d) Explain why reflex actions could be especially important to new-born animals in the wild. [1]

8 © UCLES 2014 0654/22/M/J/14 4 (a) (i) Hydrogen and carbon are elements. The gaseous hydrocarbon, propane, is a compound. Use these examples to explain the difference between elements and compounds. [2] (ii) State one raw material from which hydrocarbons like propane can be obtained. [1] (iii) State the name of a process that can be used to separate propane gas from the raw material you have named in (ii). [1] (iv) State one use of propane. [1] (b) Fig. 4.1 shows a simplified diagram of a process that is used to produce hydrocarbons known as alkenes. reaction vessel containing a catalyst at high temperature saturated hydrocarbons mixture of products including alkenes Fig. 4.1 (i) Name the process shown in Fig. 4.1. [1]

9 © UCLES 2014 0654/22/M/J/14 [Turn over (ii) State what is meant by the word saturated when it is used to describe hydrocarbon molecules. [1] (iii) Table 4.1 shows some of the compounds produced during the process shown in Fig. 4.1. Table 4.1 compound produced methane ethene propene State which of the compounds shown in Table 4.1 are examples of alkenes. [1] (iv) Complete the diagram below to show the structure of one molecule of ethene. H C [2]

10 © UCLES 2014 0654/22/M/J/14 5 A student carries out a series of experiments to investigate magnetism. (a) Fig. 5.1 shows the apparatus used in the first experiment. N S piece of iron stand thread magnet Fig. 5.1 A piece of unmagnetised iron is brought close to a suspended permanent magnet. Describe what the student observes. [1] (b) (i) Fig. 5.2 shows the apparatus used in the second experiment. N S N S stand thread magnet magnet Fig. 5.2 Another permanent magnet is brought close to the suspended magnet. Describe what the student observes. [1]

11 © UCLES 2014 0654/22/M/J/14 [Turn over (ii) Fig. 5.3 shows how the apparatus used in the second experiment is rearranged for the third experiment. N S N S stand thread magnet magnet Fig. 5.3 Describe what the student observes. [1] (iii) State a general rule of magnetism shown by these experiments. [1] (c) Fig. 5.4 shows a circuit containing three lamps connected in series. Z Y X Fig. 5.4 (i) The current through lamp X is 0.5 A. State the current through lamp Y. current = A [1]

12 © UCLES 2014 0654/22/M/J/14 (ii) The voltage across lamp X is 1.5 V. Show that the resistance of lamp X is 3 Ω. State the formula that you use and show your working. formula working resistance = Ω [2] (iii) Each of the lamps has a resistance of 3 Ω. Calculate the combined resistance of the three lamps in series. Show your working. resistance = Ω [2]

13 © UCLES 2014 0654/22/M/J/14 [Turn over 6 The graph in Fig. 6.1 shows the rate of removal of trees (deforestation) in a tropical rainforest in part of South America between the years 2000 and 2012. 2000 2012 2011 2010 2009 2008 2007 2006 2005 2004 2003 2002 2001 year 1500 1000 500 0 area of forest cleared / km2 Fig. 6.1 (a) (i) Describe how the rate of clearing of the forest changed between 2007 and 2012. [2] (ii) Suggest a possible reason for the change in the rate of clearing between 2007 and 2012. [1] (b) One of the effects of deforestation is that it can contribute to an increase in the carbon dioxide concentration of the Earth’s atmosphere. (i) Explain why deforestation might have this effect. [2]

14 © UCLES 2014 0654/22/M/J/14 (ii) Explain why an increase in the carbon dioxide concentration of the Earth’s atmosphere is undesirable. [2] (c) State two other effects of deforestation, apart from causing an increase in atmospheric carbon dioxide. 1 2 [2] (d) Suggest two reasons why people cut down trees. 1 2 [2]

15 © UCLES 2014 0654/22/M/J/14 [Turn over 7 The isotope technetium-99 is used in medical tests as a radioactive tracer. It emits γ-(gamma) radiation that medical equipment can detect in the human body. (a) State the meaning of the term isotope. [1] (b) Fig. 7.1 shows the results of an experiment to measure how the radioactivity of technetium-99 changes with time. 0 4 8 12 time / hours activity of isotope / counts per second 16 20 24 28 2000 1600 1200 800 400 0 Fig. 7.1 The results plotted in Fig. 7.1 have already been corrected for a background radiation of 50 counts per second. (i) Explain what is meant by the term background radiation. [1] (ii) Sketch on Fig. 7.1, the graph for the results before the correction for background radiation. [2]

16 © UCLES 2014 0654/22/M/J/14 (c) Use lines to link the three types of radiation on the left with their correct property on the right. Draw only three lines. α (alpha) radiation β (beta) γ (gamma) cannot pass through several sheets of paper property not dangerous can pass through 1 cm of lead has a negative charge [2] (d) γ-rays are one part of the electromagnetic spectrum. Fig. 7.2 shows an incomplete electromagnetic spectrum. gamma-rays X-rays visible light infra-red microwaves Fig. 7.2 (i) Use words from the list to complete the electromagnetic spectrum in Fig. 7.2. infra-sound radio waves seismic waves ultrasound ultraviolet water waves [2] (ii) State the part of the electromagnetic spectrum which has the shortest wavelength. [1]

17 © UCLES 2014 0654/22/M/J/14 [Turn over (e) Fig. 7.3 shows a balloon being rubbed by a cloth. balloon cloth Fig. 7.3 The cloth becomes positively charged. The balloon becomes negatively charged. Explain in terms of electrons why this happens. [2]

18 © UCLES 2014 0654/22/M/J/14 8 (a) State two reasons why plants need water. 1 2 [2] (b) Transpiration is the loss of water from a plant to the atmosphere. (i) Name the part of the plant where most of this water loss occurs. [1] (ii) State the source of water used by plants to replace these losses in transpiration. [1] (c) Fig. 8.1 shows how the rate of transpiration from a mahogany tree varied over a period of two days. rate of transpiration 00.00 06.00 12.00 18.00 24.00 time / hours 06.00 12.00 18.00 24.00 day 1 day 2 Fig. 8.1 (i) Describe how the rate of transpiration of the mahogany tree changed between 03.00 and 12.00 hours on day 1. [2]

19 © UCLES 2014 0654/22/M/J/14 [Turn over (ii) State the time at which the rate of transpiration was highest on day 1. [1] (iii) Suggest one reason why the rate of transpiration was highest at this time. [1] (iv) Between 10.00 and 13.00 on day 2, the rate of transpiration decreased. State how this could be explained by a change in the external conditions. [1]

20 © UCLES 2014 0654/22/M/J/14 9 (a) Fig. 9.1 shows one atom of the element sulfur. This sulfur atom has a nucleon number of 32. L M Fig. 9.1 (i) Name the parts labelled L and M in Fig. 9.1. L M [2] (ii) State what is meant by the term nucleon number of 32. [2] (b) (i) Fig. 9.2 shows the structure of one molecule of sulfur dioxide. S O O Fig. 9.2 Deduce whether ionic or covalent chemical bonds are present in a sulfur dioxide molecule. Explain your answer. type of bond explanation [1]

21 © UCLES 2014 0654/22/M/J/14 [Turn over (ii) Explain why the presence of sulfur dioxide in the atmosphere causes the water in some lakes to become acidic. [2] (c) Fig. 9.3 shows apparatus used to measure the rate of reaction between magnesium and dilute sulfuric acid. water gas measuring cylinder magnesium dilute sulfuric acid Fig. 9.3 (i) State two ways in which the rate of the reaction can be increased. 1 2 [2] (ii) Name the two products of the reaction. 1 2 [2]

22 © UCLES 2014 0654/22/M/J/14 10 (a) Drinks such as lemonade often contain sugar. (i) Describe how sugar is used in the body. [2] (ii) Explain one way in which too much sugar in the diet can be harmful to health. [2] (b) Fig. 10.1 shows the ingredients of a canned lemonade drink, and nutritional information about the lemonade. LEMONADE Nutritional information (per 100 cm3): Ingredients: water, sucrose, glucose syrup, citric acid, flavouring, colouring, preservative energy protein fats carbohydrates of which sugars salt fibre 145 kJ trace trace 9.5 g 8.5 g trace 0.3 g Fig. 10.1 (i) Most of the carbohydrate in the lemonade drink is sugar. Describe how you could test the lemonade drink to see if it contains reducing sugar. [2]

23 © UCLES 2014 0654/22/M/J/14 [Turn over (ii) Explain what is meant by fibre, and state why fibre is important in the diet. [2] (iii) Although the drink is called ‘lemonade’, it does not contain any lemons. Name a vitamin that would be in the drink if it contained lemons, and describe why this vitamin is important in the body. vitamin importance in the body [2] (c) Name a carbohydrate that is a large molecule made from smaller simple sugar units. [1]

24 © UCLES 2014 0654/22/M/J/14 11 (a) Fig. 11.1 is a ray diagram showing a lens being used to light a fire. light ray Fig. 11.1 (i) State the name that is given to the shape of the lens shown in Fig. 11.1. [1] (ii) State what name is given to the distance between the lens and the fire in Fig. 11.1. [1] (iii) On Fig. 11.1 label the principal focus with the letter P. [1] (b) Fig. 11.2 shows a wave. Fig. 11.2 On Fig. 11.2 mark and label (i) one wavelength, [1] (ii) the amplitude of the wave. [1]

25 © UCLES 2014 0654/22/M/J/14 [Turn over (c) Table 11.1 lists the highest and lowest sound frequencies of some musical instruments. Table 11.1 musical instrument lowest frequency / Hz highest frequency / Hz flute 260 2640 guitar 70 1170 piano 30 4190 trumpet 170 1050 violin 200 3520 (i) A person’s singing voice has a frequency range from 200 Hz to 900 Hz. State which instrument has a similar frequency range. [1] (ii) State which instrument can produce the sound with the highest pitch. [1] (iii) State the lowest and highest values of frequency that can be heard by a human. lowest Hz highest Hz [2] (d) A trumpet is made of brass. The volume of the brass used to make the trumpet is 200 cm3 and it has a mass of 1500 g. Calculate the density of brass. State the formula that you use and show your working. State the unit of your answer. formula working density = unit [3]

26 © UCLES 2014 0654/22/M/J/14 12 (a) (i) State one reason why fertilisers are added to soil in which crops are grown. [1] (ii) Some of the compounds in fertilisers contain the element nitrogen. State two other elements, needed by growing crops, that are usually added to soil in fertilisers. 1 2 [2] (iii) Fertilisers contain compounds such as ammonium nitrate and urea. Ammonium nitrate has the chemical formula NH4NO3. Urea has the chemical formula (NH2)2CO. Calculate the total number of atoms that are shown combined in the formula of urea. [1] (b) (i) A student is given a white solid and is told that it is either ammonium nitrate or ammonium sulfate. She adds sodium hydroxide solution to some of the solid contained in a test-tube, and then warms the mixture gently. Fig. 12.1 shows what the student observed. gentle heat mixture of white solid and sodium hydroxide solution damp red litmus paper litmus paper turns blue Fig. 12.1

27 © UCLES 2014 0654/22/M/J/14 Explain the observation shown in Fig. 12.1. [2] (ii) The student then makes an aqueous solution of the white solid and adds hydrochloric acid and barium chloride solution. State what would be observed, if anything, if the white solid is ammonium nitrate, ammonium sulfate. [2] (c) Calcium carbonate is another compound that is sometimes added to soil. State and explain how calcium carbonate can improve the quality of soil used for crops. [2]

28 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. 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 2014 0654/22/M/J/14 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 2014 series 0654 CO-ORDINATED SCIENCES 0654/22 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 2014 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 2014 0654 22 1 (a) helium ; aluminium ; chlorine ; [3] (b) (i) B and C (both needed) ; [1] (ii) C ; [1] (iii) D ; [1] (c) (i) electrolysis ; [1] (ii) copper chloride → copper + chlorine ;; (L.H.S ; + R.H.S ;) [2] [Total: 9] 2 (a) suitable scales ; all four key points identified ; only positive gradient for acceleration, only negative gradient for deceleration, horizontal straight line for constant speed ; [3]

Page 3 Mark Scheme Syllabus Paper IGCSE – May/June 2014 0654 22 (b) distance = speed × time ; = 12 × 10 = 120 (m) ; [2] (c) (i) kinetic ; [1] (ii) gravitational potential energy ; [1] (iii) joule and J (both required) ; [1] [Total: 8] 0 10 20 30 40 50 60 12 10 8 6 4 2 0 time / s speed / m per s

Page 4 Mark Scheme Syllabus Paper IGCSE – May/June 2014 0654 22 3 (a) sensitivity / movement ; [1] (b) (i) three neurones correctly labelled as below ;;; [3] (ii) relay / connector ; [1] (iii) behaviour more flexible / coordinated with other responses / can be controlled by the brain ; [1] (c) conscious / consciously controlled ; not automatic ; always involves the brain ; [max 2] (d) do not need to be learned / protect the young animal from danger ; [1] [Total: 9] 4 (a) (i) hydrogen and carbon (each) contains one type of atom / is found in the Periodic Table / cannot be broken down into simpler substances ; propane contains different atoms (allow elements) bonded together / can be broken down into simpler substances / into elements ; [2] (ii) petroleum / natural gas ; [1] (iii) fractional distillation ; [1] (iv) heating / lighting / burners / cooking / vehicle fuel / refrigerant / feedstock ; [1] sensory neurone motor neurone painful stimulus response relay neurone

Page 5 Mark Scheme Syllabus Paper IGCSE – May/June 2014 0654 22 (b) (i) (catalytic) cracking ; [1] (ii) only single bonds (in a molecule) / contains maximum possible hydrogen atoms ; [1] (iii) ethene and propene (both required) ; [1] (iv) (2 × C and 4 × H; all else correct) ; [2] [Total: 10] 5 (a) (magnet) moves towards / attraction ; [1] (b) (i) (magnet) moves towards / will line up / owtte ; [1] (ii) magnet moves away from / is repelled by ; [1] (iii) like poles repel / unlike poles attract / only magnets repel ; [1] (c) (i) 0.5 (A) ; [1] (ii) (R) = Ι V ; = 0.5 1.5 = 3 (Ω) ; [2] (iii) (R =) R1 + R2 + R3 = 3 + 3 + 3 ; = 9 (Ω) ; [2] [Total: 9] 6 (a) (i) decreased ; from 1350 to 400 km2 (over 5 year period) / by 950 km2 (over 5 year period) / use of numbers ; rapid decrease, then slower ; [max 2] (ii) government regulation / increased awareness / reduced demand for timber / land / decreased areas of forest remaining ; [1] (b) (i) fewer trees absorbing CO2 ; by photosynthesis ; [2] H H C H H C

Page 6 Mark Scheme Syllabus Paper IGCSE – May/June 2014 0654 22 (ii) CO2 acts as greenhouse gas / traps thermal OR infra-red energy ; global warming ; [2] (c) soil erosion / loss of soil ; flooding ; extinction of species ; loss of habitat ; [max 2] (d) to get timber ; for fuel ; clearing land for housing ; clearing land for agriculture ; clearing land for roads / factories ; [max 2] [Total: 11] 7 (a) element whose atoms contain the same number of protons but different numbers of neutrons ; [1] (b) (i) the natural ionising radiation that is always present in the environment / owtte ; [1] (ii) curve above original ; approx. 50 cps (one square) above ; [2] (c) ;; (3 correct = 2 marks, 1 correct = 1 mark) [2] α- (alpha) radiation β- (beta) γ- (gamma) cannot pass through several sheets of paper property not dangerous can pass through 1 cm of lead has a negative charge

Page 7 Mark Scheme Syllabus Paper IGCSE – May/June 2014 0654 22 (d) (i) ultraviolet (LHS) ; radiowaves (RHS) ; [2] (ii) gamma end / left hand side ; [1] (e) friction removes electrons / electrons are transferred ; from cloth to balloon ; [2] [Total: 11] 8 (a) photosynthesis ; transport ; support ; turgor ; part of cytoplasm ; [max 2] (b) (i) leaves / stomata / mesophyll ; [1] (ii) soil ; [1] (c) (i) increases ; after a delay / slowly at first, then faster ; [2] (ii) 15.00 (hours) ; [1] (iii) high temperature / windy / low humidity / high light intensity / stomata open ; [1] (iv) more cloud cover / cooler / less wind / less light / increased humidity ; [1] [Total: 9] 9 (a) (i) L nucleus ; M electron ; [2] (ii) idea that nucleons are sub-atomic particles / protons and neutrons in the nucleus ; total number of these is 32 ; [2] (b) (i) (covalent – no mark) idea that non-metallic atoms are bonded / sulfur dioxide exists as molecules / sulfur dioxide is gaseous ; [1] (ii) dissolves / reacts with (rain) water ; rain water becomes acidic / now contains (dilute) sulfuric acid ; acid rain falls into lake ; water evaporates but sulfuric acid does not ; [max 2]

Page 8 Mark Scheme Syllabus Paper IGCSE – May/June 2014 0654 22 (c) (i) increase temperature ; increase surface area of magnesium / use magnesium in powder form ; increase concentration of the acid ; [max 2] (ii) magnesium sulfate ; hydrogen ; [2] [Total: 11] 10 (a) (i) as a source of energy ; used in respiration ; [2] (ii) remains on the teeth / encourages bacterial growth ; causing dental decay ; OR causes obesity ; leading to CHD / diabetes / arthritis ; [max 2] (b) (i) use Benedict’s solution ; heat ; red / orange (ppt) ; [max 2] (ii) roughage / indigestible material / plant matter / cellulose ; prevents constipation / promotes peristalsis / AW ; [2] (iii) (vitamin) C ; for skin / gums / prevents scurvy ; [2] (c) starch / glycogen / cellulose ; [1] [Total: 11] 11 (a) (i) convex ; [1] (ii) focal length ; [1] (iii) P drawn at focus of light rays ; [1] (b) (i) distance between two identical points on consecutive waves labelled ; [1] (ii) amplitude correctly labelled ; [1] (c) (i) trumpet ; [1] (ii) piano ; [1] (iii) lowest 20 (Hz) ; highest 20 000 (Hz) ; [2]

Page 9 Mark Scheme Syllabus Paper IGCSE – May/June 2014 0654 22 (d) density = volume mass ; 200 1500 = 7.5 ; g / cm3 ; [3] [Total: 12] 12 (a) (i) increase crop yield / replace nutrients (removed by crops) ; [1] (ii) potassium ; phosphorus ; [2] (iii) 8 ; [1] (b) (i) heating an ammonium salt with sodium hydroxide releases ammonia ; ammonia turns (damp red) litmus paper blue ; ammonia is alkaline ; [max 2] (ii) no reaction / no observable change ; white precipitate / solid formed / mixture goes cloudy ; [2] (c) reduces soil acidity ; by reacting with / neutralising acid in soil ; reference to flocculation / improved drainage ; provides calcium / improves uptake of NPK ; [max 2] [Total: 10]