Cambridge IGCSE Sciences - Co-ordinated (Double) 0654 — 2015 Oct/Nov Paper 2 · Variant 2

This document consists of 29 printed pages and 3 blank pages. DC (CW/FD) 104349/3 © UCLES 2015 [Turn over Cambridge International Examinations Cambridge International General Certificate of Secondary Education * 8 6 2 3 0 3 7 6 8 7 * CO-ORDINATED SCIENCES 0654/22 Paper 2 (Core) October/November 2015 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, graphs, tables or rough working. 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 0654/22/O/N/15 © UCLES 2015 1 Fig. 1.1 shows a compost bin. Gardeners use these bins to produce compost which is a useful fertiliser for plants. They put weeds, dead leaves and other garden waste into the bin. Over time, these break down to produce the fertiliser. removable lid garden waste placed in here compost bin fertiliser is removed here Fig. 1.1 (a) Name the process that breaks down the garden waste into fertiliser for plants. …[1] (b) The organisms that break down the garden waste are respiring aerobically. (i) Name two substances that they would produce in their respiration. 1 … 2 …[2] (ii) Name two mineral ions that the fertiliser will contain. 1 … 2 …[2]

3 0654/22/O/N/15 © UCLES 2015 [Turn over (iii) Suggest two things that a gardener could do to help the organisms in the compost bin to respire more quickly. 1 … 2 …[2] (c) Greenhouse gases are released as the compost is produced in the bin. (i) State the name of a greenhouse gas. …[1] (ii) Describe the environmental effect of increased amounts of greenhouse gases in the atmosphere. … …[1]

4 0654/22/O/N/15 © UCLES 2015 2 (a) A student carries out an experiment to investigate the reactivities of metals. She adds dilute hydrochloric acid to four test-tubes each containing one of the four metals, calcium, copper, magnesium and zinc. (i) Name the gas produced when metals react with dilute hydrochloric acid. …[1] (ii) Describe a test and its result for the gas you have named in (i). test … result …[2] (iii) The student’s observations are shown in Table 2.1. Complete the table by writing the names of the four metals, calcium, copper, magnesium and zinc into the correct boxes. Table 2.1 observation metal … … … … [2] (iv) Explain why potassium and sodium must not be included in this investigation. … … …[2]

5 0654/22/O/N/15 © UCLES 2015 [Turn over (b) Fig. 2.1 shows a ring made of an alloy of gold. ring made of an alloy of gold Fig. 2.1 Alloys of gold usually cost less than pure gold. Suggest one other advantage of making a ring from an alloy of gold rather than pure gold. … …[1]

6 0654/22/O/N/15 © UCLES 2015 3 (a) Fig. 3.1 shows a speed / time graph for a train. 0 0 5 10 15 20 25 30 50 100 150 time / s speed m / s 200 250 300 Fig. 3.1 (i) Describe the motion of the train over the first 100 seconds. …[1] (ii) On Fig. 3.1, mark with an X the point at which the train stops moving. [1] (b) Fig. 3.2 shows some of the forces acting on the train. 35 000 N 65 000 N F Fig. 3.2 The engine of the train produces a thrust of 65 000 N. There is a 35 000 N force opposing the motion due to friction in the wheels. The train is travelling at a constant speed. (i) Force F is another force opposing the motion due to friction. Suggest what is causing this force. …[1]

7 0654/22/O/N/15 © UCLES 2015 [Turn over (ii) The train travels at a constant speed. Calculate the size of force F. Show your working. force = … N [1] (c) The engine is powered by diesel fuel. The combustion of diesel fuel releases energy, which is transformed into kinetic energy. (i) State the form of energy stored in a fuel. …[1] (ii) Only 20% of the energy stored in the diesel fuel is transformed into kinetic energy. The rest of the energy is transformed into other forms of energy. State one of these other forms of energy. …[1] (d) The track for the train is composed of short lengths of steel rails with small gaps left between them. This is shown in Fig. 3.3. Fig. 3.3 Suggest the reason for leaving these small gaps. … … …[2]

8 0654/22/O/N/15 © UCLES 2015 (e) The steel rails are made from steel blocks. Each block is a cube, with sides of 0.5 m. The density of steel is 7800 kg / m3. (i) Calculate the volume of a steel block in m3. Show your working. volume = … m3 [1] (ii) Calculate the mass of the block of steel in kilograms. State the formula that you use and show your working. formula working mass = … kg [2]

9 0654/22/O/N/15 © UCLES 2015 [Turn over 4 Fig. 4.1 shows a liquid fossil fuel being extracted from rock layers beneath the sea bed. layers of rock liquid fossil fuel drilling rig sea bed Fig. 4.1 (a) Name the fossil fuel being extracted. …[1]

10 0654/22/O/N/15 © UCLES 2015 (b) The material extracted from the rock is a mixture of hydrocarbons. Fig. 4.2 shows a simplified diagram of industrial apparatus being used to separate simpler mixtures, P and Q, from the fossil fuel. 400 °C 40 °C 3 4 hot fossil fuel Fig. 4.2 (i) Name the process shown in Fig. 4.2. …[1] (ii) Mixture P is gaseous. State one use for mixture P. …[1] (iii) Mixture Q is liquid and used as car fuel. Name mixture Q. …[1]

11 0654/22/O/N/15 © UCLES 2015 [Turn over (c) Fig. 4.3 shows the structure of a hydrocarbon molecule. C H C H H H H H Fig. 4.3 (i) State the chemical formula and name of the hydrocarbon shown in Fig. 4.3. chemical formula … name … [2] (ii) Draw the structure of an unsaturated hydrocarbon molecule that has the same number of carbon atoms as the molecule in Fig. 4.3. [2]

12 0654/22/O/N/15 © UCLES 2015 (d) Fig. 4.4 shows a simplified diagram of an industrial process in which alkenes are produced from alkanes. mixture of large alkane molecules heat catalyst mixture of small alkane and alkene molecules Fig. 4.4 (i) Name the process shown in Fig. 4.4. …[1] (ii) Describe a chemical test used to distinguish between an alkane and an alkene. test … … result for an alkane … … result for an alkene … … [3]

13 0654/22/O/N/15 © UCLES 2015 [Turn over Please turn over for Question 5.

14 0654/22/O/N/15 © UCLES 2015 5 An athlete does a two-hour training session every day. Fig. 5.1 shows how the amount of glycogen in his liver changed over a period of two days. 0.00 4.00 8.00 day 1 day 2 12.00 16.00 20.00 0.00 4.00 8.00 12.00 16.00 20.00 0.00 0 5 10 20 percentage of liver mass made up of glycogen / % training session training session Fig. 5.1 (a) (i) For day 1, state the percentage of the liver mass that was made up of glycogen at the start of the training session, … at the end of the training session. … [2] (ii) Explain why the amount of glycogen changed during the training sessions. … … …[2]

15 0654/22/O/N/15 © UCLES 2015 [Turn over (iii) The amount of glycogen in the liver changed between the two training sessions. Describe this change and explain why it happened. description … … … explanation … … …[3] (iv) Suggest an explanation for the different shape of the graph after the training session on day 2, compared to after the training session on day 1. … … …[1] (b) Glycogen is a carbohydrate. (i) Name the chemical elements present in a carbohydrate. … … … [3] (ii) Name the smaller molecules that form the basic units of a large glycogen molecule. …[1] (c) During a training session, the athlete will secrete adrenaline. (i) Suggest how the adrenaline would affect the amount of glycogen in the liver. Explain your answer. … …[1] (ii) State one other effect of adrenaline on the body. … …[1]

16 0654/22/O/N/15 © UCLES 2015 6 (a) A cyclist has a mirror placed on his handlebars so that he can see behind him. The cyclist sees a taxi in his mirror as shown on Fig. 6.1. TA X I Fig. 6.1 Describe two characteristics of an image seen in a plane mirror. 1 … 2 …[2] (b) A reflector on the back of the bicycle is made from many small glass prisms, one of which is shown in Fig. 6.2. 45° P glass prism Fig. 6.2 A ray of light is incident on the back surface of the prism at point P at an angle of 45°. The critical angle for glass is 42°. (i) Explain why light does not leave the prism at point P. … …[1]

17 0654/22/O/N/15 © UCLES 2015 [Turn over (ii) On Fig. 6.2, draw the path of the ray of light as it leaves point P and travels through the glass and then back into the air again. [2] (c) The air in a bicycle tyre exerts a pressure on the walls of the tyre. Describe, in terms of particles, how a gas exerts a pressure on the walls of a tyre. … … … …[2] (d) As the cyclist rides, he cools down by sweating. The sweat evaporates from the surface of the cyclist’s skin. Explain, in terms of particles, why sweating cools the skin. … … … …[2]

18 0654/22/O/N/15 © UCLES 2015 7 Fig. 7.1 shows the male reproductive system, as seen from the side. X Y Fig. 7.1 (a) (i) On Fig. 7.1, label the urethra and the sperm duct. [2] (ii) Name the structures labelled X and Y. X … Y … [2] (b) State two functions of the testes. 1 … 2 …[2]

19 0654/22/O/N/15 © UCLES 2015 [Turn over (c) Sperm cells are mobile (able to move). Fig. 7.2 shows how mobility of sperm cells varies with temperature. 10 0 50 75 100 15 20 temperature / °C percentage of maximum mobility / % 25 30 Fig. 7.2 (i) State the temperature at which the sperm cells are most mobile. …[1] (ii) Suggest why decreased sperm mobility would reduce a man’s fertility. … …[1] (iii) Human core body temperature is 37 °C. Use this information and the information in Fig. 7.2 to explain the advantage of the testes being in the scrotum. … … …[2]

20 0654/22/O/N/15 © UCLES 2015 8 (a) Two cars A and B are left in the hot sun during the day. Car A is painted black and car B is painted white. car A painted black car B painted white Fig. 8.1 Energy from the sun heats both cars. State the method of energy transfer between the Sun and the Earth. …[1] (b) Car A has two headlights and two rear lights. The lamp inside each light is connected in parallel with each of the other lamps across a 12 V battery. (i) Complete the circuit diagram below to show how the lamps are connected to the battery. Include one switch in the circuit which will control the two lamps inside the headlights and a second switch which will control the two lamps inside the rear lights. Label clearly the lamps for the two headlights and the two rear lights. 12 V [4]

21 0654/22/O/N/15 © UCLES 2015 [Turn over (ii) The current passing through one lamp in a headlight is 4.8 A. Show that the resistance of this lamp is 2.5 Ω. State the formula that you use and show your working. formula working [2] (iii) Two other lamps in the car are connected in series with each other. Each lamp has a resistance of 14 Ω. Calculate the combined resistance of the two lamps connected in series. resistance = … Ω [1]

22 0654/22/O/N/15 © UCLES 2015 (c) Some cars are fitted with proximity detectors to warn the driver when the car is too close to other objects. These detectors use ultrasound. Fig. 8.2 shows a car fitted with an ultrasound proximity detector. car Fig. 8.2 (i) The ultrasound waves used have a frequency of 40 000 Hz. This means that they are usually outside the audible range of a human. Write down the normal audible human range. … Hz to … Hz [2] (ii) State the meaning of the term frequency. … …[1] (iii) An ultrasound wave is emitted from the sensor in the car and the wave, reflected from a nearby object, is received 0.002 s later. The speed of ultrasound waves in air is 34 000 cm / s. Calculate the distance of the car from the nearby object. State the formula that you use and show your working. formula working distance = … cm [2]

23 0654/22/O/N/15 © UCLES 2015 [Turn over 9 Nitrogen is an element in Group V of the Periodic Table. (a) A nitrogen atom has a proton number of 7 and a nucleon number of 14. (i) State the number of electrons in a nitrogen atom. …[1] (ii) Describe the composition of the nucleus of this nitrogen atom. … … …[2] (iii) Explain in terms of numbers of protons and electrons why the nitride ion, N3–, has a negative electrical charge. … …[1]

24 0654/22/O/N/15 © UCLES 2015 (b) Fig. 9.1 shows apparatus which can be used to make ammonia, NH3. The piston of gas syringe A is pushed in slowly, and the mixture of nitrogen and hydrogen moves through the small pieces of heated iron into gas syringe B. gas syringes iron heat mixture containing ammonia piston heat A A B B mixture of nitrogen and hydrogen Fig. 9.1 Some nitrogen reacts with hydrogen on the surface of the heated iron. (i) Construct a word equation for the reaction that occurs in the apparatus shown in Fig. 9.1. + [1] (ii) Describe a chemical test used to show that ammonia is produced. State the result of this test. test … result …[2] (iii) The iron in this reaction acts as a catalyst. State the meaning of the term catalyst. … … …[2] (c) Suggest the name of an acid that reacts with ammonia to produce ammonium sulfate. …[1]

25 0654/22/O/N/15 © UCLES 2015 [Turn over 10 (a) In many power stations, energy is transferred to turbines to turn generators. (i) A nuclear power station usually has a greater efficiency than a power station which burns fossil fuels. Explain the meaning of the term efficiency. … …[1] (ii) In a nuclear power station, fission of uranium-235 nuclei takes place. Describe what happens to the nuclei of uranium-235, in this process. … …[1] (b) In a nuclear power station, technicians work close to radioactive sources. These sources emit α-radiation, β-radiation and γ-radiation. (i) State which of these radiations is part of the electromagnetic spectrum. …[1] (ii) State which of these radiations does not have an electric charge. …[1] (iii) Describe two effects, harmful to the technicians, from ionising radiation emitted by radioactive sources. 1 … … 2 … …[2] (iv) State one way in which these workers could be protected from ionising radiation. … …[1]

26 0654/22/O/N/15 © UCLES 2015 11 Fig. 11.1 shows part of the gas exchange surface of a leaf. mesophyll cells water nucleus chloroplast cell wall Fig. 11.1 (a) Using the information in Fig. 11.1, state two ways in which this surface is adapted for efficient gas exchange. 1 … 2 …[2] (b) (i) Name the gas that is entering the cells of the leaf from the air during a period of bright sunlight. …[1] (ii) Name the process by which this gas moves into the cells of the leaf. …[1] (c) The mesophyll cells shown in Fig. 11.1 are found in the middle of a leaf. Name three other types of cell that leaves contain. 1 … 2 … 3 …[3]

27 0654/22/O/N/15 © UCLES 2015 [Turn over 12 (a) Fig. 12.1 shows a small piece of potassium being added to water. The water is coloured green by full-range indicator solution (Universal Indicator). beaker water containing full-range indicator potassium Fig. 12.1 (i) Explain why potassium is an example of an element and water is an example of a compound. potassium is an element because … … water is a compound because … …[2] (ii) State and explain the colour change observed in the beaker when the potassium reacts with the water. green colour change … to … explanation … …[2] (iii) During the reaction between potassium and water, the piece of potassium melts. Explain this observation. … …[1] (iv) When lithium is used instead of potassium in the experiment the colour change in (ii) is the same. Predict one observation that will be different. … …[1]

28 0654/22/O/N/15 © UCLES 2015 (b) Chloramine, NH2Cl, is a compound that is added to water supplies as one of the processes used in drinking water purification. Fig. 12.2 shows the structure of a chloramine molecule. N Cl H H Fig. 12.2 (i) Predict the type of chemical bonding between the atoms in a chloramine molecule. Explain your answer. type of bonding … explanation … …[2] (ii) Suggest how chloramine helps to purify drinking water supplies. … …[1] (iii) State one other process that is used in the purification of drinking water. …[1]

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32 0654/22/O/N/15 © UCLES 2015 Group The Periodic Table of the Elements 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 91 238 231 147 237 244 243 247 247 251 252 257 258 259 260 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 82 209 209 210 222 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 55 226 223 Ra Radium 88 a X b a = relative atomic mass X = atomic symbol b = atomic (proton) number Key DATA SHEET * 58–71 Lanthanoid series † 90–103 Actinoid series The volume of one mole of any gas is 24dm3 at room temperature and pressure (r.t.p.). 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.

® IGCSE is the registered trademark of Cambridge International Examinations. CAMBRIDGE INTERNATIONAL EXAMINATIONS Cambridge International General Certificate of Secondary Education MARK SCHEME for the October/November 2015 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 October/November 2015 series for most Cambridge IGCSE®, Cambridge International A and AS Level components and some Cambridge O Level components.

Page 2 Mark Scheme Syllabus Paper Cambridge IGCSE – October/November 2015 0654 22 © Cambridge International Examinations 2015 1 (a) decomposition / decay / respiration ; [1] (b) (i) carbon dioxide ; water ; [2] (ii) nitrate ; magnesium ; other named essential mineral ion ; [max 2] (iii) keep the compost bin warm ; mix / aerate the compost ; break up compost into smaller pieces ; [max 2] (c) (i) CO2 / methane ; [1] (ii) traps solar energy / causes global warming ; [1] [Total: 9] 2 (a) (i) hydrogen ; [1] (ii) lighted splint ; ‘pops’ ; [2] (iii) calcium magnesium zinc copper ;; (four correct = 2 marks, one or two correct = 1 mark) [2] (iv) potassium and or sodium very / too reactive; reference to safety of student ; [2] (b) alloy is stronger than pure gold ; [1] [Total: 8] 3 (a) (i) constant speed (of 25 m / s) ; [1] (ii) X at time 250 s ; [1] (b) (i) air resistance ; [1] (ii) 30 000 (N) ; [1]

Page 3 Mark Scheme Syllabus Paper Cambridge IGCSE – October/November 2015 0654 22 © Cambridge International Examinations 2015 (c) (i) chemical ; [1] (ii) thermal / sound ; [1] (d) rails expand during hot weather ; will buckle if no gap left ; [2] (e) (i) volume = 0.53 = 0.125 (m3) ; [1] (ii) (mass =) density × volume ; = 7800 × 0.125 = 975 (kg) ; [2] [Total: 11] 4 (a) petroleum / crude oil ; [1] (b) (i) fractional distillation ; [1] (ii) heating / cooking / other correct ; [1] (iii) gasoline / petrol ; [1] (c) (i) C2H6 ; ethane; [2] (ii) C =C double bond ; all else correct ; [2] (d) (i) cracking ; [1] (ii) (react / mix / shake with) bromine (solution) ; bromine not decolourised by alkane ; bromine decolourised by alkene ; [3] [Total: 12]

Page 4 Mark Scheme Syllabus Paper Cambridge IGCSE – October/November 2015 0654 22 © Cambridge International Examinations 2015 5 (a) (i) 8.5(%) (accept 8–9) ; 5(%) (accept 4.5–5.5) ; [2] (ii) glycogen converted to sugar / glucose ; for (increased) respiration ; provides energy (for training / muscle contraction) ; [max 2] (iii) (description): increases ; (from 5) to 8.5 / back to original level ; (explanation): glucose converted to glycogen ; energy storage ; [max 3] (iv) less food eaten / more activity on day 2 (after training) ; [1] (b) (i) carbon ; hydrogen ; oxygen ; [3] (ii) glucose ; [1] (c) (i) decrease – (no mark) adrenaline causes glycogen breakdown / increased blood glucose ; [1] (ii) increased heart rate ; AVP ; [max 1] [Total: 14] 6 (a) upright ; laterally inverted (or description) ; same size as object ; [max2] (b) (i) no refraction / total internal reflection / angle (of incidence) greater than critical angle ; [1] (ii) ray reflects at P and on opposite side of prism ; emergent ray parallel to incident ray ; [2] (c) particles constantly in motion ; collide with walls of tyre ; force of collisions exerts a pressure ; [max 2]

Page 5 Mark Scheme Syllabus Paper Cambridge IGCSE – October/November 2015 0654 22 © Cambridge International Examinations 2015 (d) heat transferred from body to sweat / absorbed by sweat from body / heat energy in body reduced by sweating ; kinetic energy of water molecules increases / water molecules move faster ; faster moving / more energetic (water) molecules escape / leave the surface / water molecules turn to gas / vapour ; break bonds / break forces of attraction between molecules ; (KE) / energy of (remaining) water molecules (in sweat) decreases ; [max 2] [Total: 9] 7 (a) (i) [2] (ii) X = prostate gland ; Y = testis ; [2] (b) sperm production ; production / secretion, of hormones / testosterone ; [2] (c) (i) 0 ºC; [1] (ii) sperm less likely to be able to reach the egg / less chance of fertilisation / owtte ; [1] (iii) scrotum is outside the main body cavity ; so lower temperature; helps maintain sperm mobility ; [max 2] [Total: 10] urethra ; sperm duct ;

Page 6 Mark Scheme Syllabus Paper Cambridge IGCSE – October/November 2015 0654 22 © Cambridge International Examinations 2015 8 (a) radiation ; [1] (b) (i) labels to head (front) lights and rear lights ; four lamps connected in parallel with battery ; switch controlling headlights ; switch controlling rear lights ; [4] (ii) (R =) I V ; = 4.8 12 (= 2.5 Ω) ; [2] (iii) 28 (Ω) ; [1] (c) (i) 20 (Hz) ; 20 000 (Hz) ; [2] (ii) number of waves generated per second (unit time) / number of waves passing a fixed point per second ; [1] (iii) distance = speed × time ; = 34 000 × 2 0.002 = 34 cm ; [2] [Total: 13] 9 (a) (i) 7; [1] (ii) contains protons and neutrons ; 7 protons and 7 neutrons ; [2] (iii) nitride has (3) more electrons than protons ; [1] (b) (i) nitrogen + hydrogen → ammonia ; [1] (ii) use of damp, red litmus / universal indicator paper ; colour change to blue / purple ; OR use hydrogen chloride gas ; white smoke / ammonium chloride ; [max 2] (iii) increases reaction rate ; without being consumed / permanently changed ; [2] (c) sulfuric (acid) ; [1] [Total: 10]

Page 7 Mark Scheme Syllabus Paper Cambridge IGCSE – October/November 2015 0654 22 © Cambridge International Examinations 2015 10 (a) (i) relationship between energy input and useful energy output ; [1] (ii) nuclei split ; [1] (b) (i) γ-radiation ; [1] (ii) γ-radiation ; [1] (iii) radiation burns ; radiation sickness ; cancer ; mutation ; damages cells ; [max 2] (iv) work behind shields / wear protective clothing / gloves / tongs ; [max 1] [Total: 7] 11 (a) folded / large surface area ; thin / permeable ; moist ; [max 2] (b) (i) carbon dioxide ; [1] (ii) diffusion ; [1] (c) epidermal cell ; guard cell ; palisade cell ; phloem ; [max 3] [Total: 7]

Page 8 Mark Scheme Syllabus Paper Cambridge IGCSE – October/November 2015 0654 22 © Cambridge International Examinations 2015 12 (a) (i) (element:) cannot be simplified / contains atoms with same proton number / contains only one type of atom / in Periodic Table ; (compound:) made of different types of atom bonded together / can be simplified / broken down into elements ; [2] (ii) (green to) blue / purple ; solution becomes alkaline / potassium hydroxide produced ; [2] (iii) reaction is exothermic / thermal energy / heat given off ; [1] (iv) less bubble / slower moving / no flame / less heat given off ; [max 1] (b) (i) covalent ; reference to bonding of non-metallic elements ; [2] (ii) kills (harmful) microorganisms / sterilises ; [1] (iii) filtration / chlorination ; (accept distillation) [1] [Total: 10]