Cambridge IGCSE Science - Combined 0653 — 2015 Oct/Nov Paper 2 · Variant 3

This document consists of 23 printed pages and 1 blank page. DC (NH/SG) 104363/4 © UCLES 2015 [Turn over * 1 7 7 9 7 5 3 1 8 7 * COMBINED SCIENCE 0653/23 Paper 2 (Core) October/November 2015 1 hour 15 minutes 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 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 24. At the end of the examination, fasten all your work securely together. The number of marks is given in brackets [ ] at the end of each question or part question. Cambridge International Examinations Cambridge International General Certificate of Secondary Education

2 0653/23/O/N/15 © UCLES 2015 1 (a) Fig. 1.1 shows the human gas exchange system. Fig. 1.1 On Fig. 1.1, draw label lines with names to show the larynx, the trachea, a bronchus. [3] (b) Some people suffer from asthma which affects the bronchioles of the gas exchange system. Fig. 1.2 shows cross sections of a normal bronchiole and a bronchiole of a person who has asthma. wall of bronchiole airway normal bronchiole bronchiole of a person with asthma airway mucus wall of bronchiole Fig. 1.2

3 0653/23/O/N/15 © UCLES 2015 [Turn over The airflow towards the alveoli is reduced if a person has asthma. Describe two features visible in Fig. 1.2 which could reduce the airflow in the bronchiole of the person suffering from asthma. 1 … 2 …[2] (c) A study is carried out to compare the breathing of people with asthma with the breathing of healthy people. The volumes of air inhaled in one minute are measured and an average is calculated for both groups. Both groups of people are tested while resting. Results average volume inhaled by a healthy person = 5.8 dm3 / minute. average volume inhaled by a person with asthma = 12.5 dm3 / minute. (i) Calculate the average percentage of extra air the person with asthma inhales per minute compared with a healthy person. Show your working. answer = … % [2] (ii) Suggest two ways in which the breathing of an asthmatic person is likely to be different from a normal person’s breathing in order to inhale a greater volume of air. 1 … 2 …[2]

4 0653/23/O/N/15 © UCLES 2015 2 Fig. 2.1 shows apparatus used to investigate the temperature changes which occur during some chemical processes. temperature sensor connected to computer insulated cup water Fig. 2.1 A citric acid solution can be made by dissolving citric acid crystals in water. The temperature sensor is placed in the water and the computer starts to log data. After 10 seconds some citric acid crystals are added to the water in a cup. The mixture is stirred until the crystals dissolve. After another 40 seconds some magnesium ribbon is placed in the solution. Fig. 2.2 shows the computer display of temperature change for the first 100 seconds. 0 0 5 10 15 20 25 30 35 temperature / °C 40 10 20 30 40 50 60 70 80 90 100 time / s citric acid added to water magnesium placed in solution Fig. 2.2

5 0653/23/O/N/15 © UCLES 2015 [Turn over (a) Complete the following sentences, choosing from the words below. decreases exothermic oxidation endothermic increases stays the same As the citric acid dissolves in the water the temperature … . This is an … process. [1] (b) Fig. 2.3 shows the appearance of the contents of the cup during the experiment. magnesium citric acid solution gas bubbles Fig. 2.3 Gas bubbles rise from the surface of the magnesium. Name the gas produced. …[1] (c) The experiment is repeated using a greater mass of citric acid dissolved in the same mass of pure water. This increases the concentration of the citric acid. Describe the effect on the reaction with magnesium caused by increasing the concentration of the citric acid. … …[1] (d) By referring to the reactivity series, explain how the results of these experiments would change if copper was used instead of magnesium. … … …[2]

6 0653/23/O/N/15 © UCLES 2015 3 Fig. 3.1 shows a girl on a skateboard track. A B C D Fig. 3.1 Fig. 3.2 shows a speed/time graph of the girl as she travels. 10 8 6 4 2 0 0 1 2 3 4 5 6 time/s speed m/s A B C D Fig. 3.2 (a) (i) Name the force that causes the girl to move down the skateboard track from A to B. …[1]

7 0653/23/O/N/15 © UCLES 2015 [Turn over (ii) The force acting on the girl has a value of 500 N. State the name of the unit whose symbol is N. …[1] (b) State the main energy transformations as the girl travels from A to D. from … energy to … energy to … energy. [2] (c) Describe the motion of the girl between points A and B, … B and C. …[2] (d) Use Fig. 3.2 to calculate the distance travelled by the girl between points B and C. State the formula you use and show your working. formula working distance = … m [2]

8 0653/23/O/N/15 © UCLES 2015 4 (a) Vitamins are needed in small quantities as part of a balanced diet. One vitamin is vitamin C. (i) State what is meant by the term balanced diet. … …[1] (ii) Explain why we need vitamin C in our diet. … …[1] (iii) Suggest why vitamin C does not need to be digested. … … …[2] (b) Table 4.1 gives details about the vitamin C content of some fruits. Table 4.1 fruit mass of vitamin C in 100 g fruit / mg mass of vitamin C in an average portion / mg apple 6 8 kiwifruit 98 74 mango 28 57 orange 53 70 watermelon 10 27 The recommended daily allowance (RDA) of vitamin C for humans is 60 mg. (i) State which of the fruits listed in Table 4.1 provide the RDA of vitamin C in just one portion. Explain your answer. … … …[2]

9 0653/23/O/N/15 © UCLES 2015 [Turn over (ii) Calculate the mass of mango needed to supply a full RDA of vitamin C. Show your working. answer = … g [2] (c) Citrus fruits provide a good source of vitamin C. However, many of them are weakly acidic. (i) Explain why the acid in the citrus fruits could be harmful for teeth if a lot of fruit is eaten. … …[1] (ii) Describe what a person can do to reduce the effects on the teeth of eating the acidic fruit. … …[1]

10 0653/23/O/N/15 © UCLES 2015 5 (a) On Fig. 5.1 draw one line from each property to show whether it describes metals or non-metals. One line has been drawn for you. properties metals non-metals good conductors of electricity form acidic oxides often have low melting points are malleable are strong Fig. 5.1 [2] (b) Fig. 5.2 shows Period 3 of the Periodic Table. A Na 23 11 Sodium Mg 24 12 Magnesium Al 27 13 Aluminium Si 28 14 Silicon P 31 15 Phosphorus S 32 16 Sulfur Cl 36.5 17 Chlorine Ar 40 18 Argon Fig. 5.2 Draw an arrow in box A which points towards the metals and away from the non-metals. [1]

11 0653/23/O/N/15 © UCLES 2015 [Turn over (c) Table 5.1 shows some observations made after a piece of sodium is dropped into some water containing full-range indicator (Universal Indicator). Complete Table 5.1 to explain each observation. Table 5.1 observation explanation bubbles of gas indicator changes from green to purple [2] (d) Sodium reacts with chlorine to form sodium chloride. (i) Fig. 5.3 shows diagrams that represent the particles in each substance. – – – + – – + – – + + + – + + – + + A B C Fig. 5.3 Complete Table 5.2 to show which diagram, A, B or C, represents each substance. Table 5.2 substance diagram chlorine sodium sodium chloride [2]

12 0653/23/O/N/15 © UCLES 2015 (ii) Describe, in terms of the loss or gain of electrons, how sodium and chloride ions are formed from sodium and chlorine atoms. … … …[2] (iii) Describe how the sodium ions and chloride ions are held together. … …[1] (iv) Zinc chloride can be made by reacting zinc with chlorine. Zinc chloride contains half as many zinc ions as chloride ions. State the chemical formula of zinc chloride. … [2]

13 0653/23/O/N/15 © UCLES 2015 [Turn over Please turn over for Question 6.

14 0653/23/O/N/15 © UCLES 2015 6 Electric power can be generated using the energy of waves on the sea. Fig. 6.1 shows a group of small wave energy converters which are anchored to the sea floor below. floating tube containing wave energy converter waves Fig. 6.1 Inside each floating tube there are several generators that convert the wave movement energy into electrical energy. (a) (i) Each floating container is 30 m long. In Fig. 6.1 each sea wave takes 10 seconds to pass along each floating container from end to end. Calculate the speed of the waves across the sea. speed = … m/s [1] (ii) A total of 10 waves passed one end of a container in 20 seconds. Calculate the frequency of the waves. Show your working and state the unit of your answer. frequency = … unit … [2] (b) The amplitude of the waves on one day was 0.5 m. State the vertical distance that each container will move through as a wave passes. distance = … m [1]

15 0653/23/O/N/15 © UCLES 2015 [Turn over (c) The generators are controlled by radio signals. A radio signal is sent from a control centre 100 km away. Fig. 6.2 shows an incomplete diagram of the electromagnetic spectrum. gamma radiation visible light Fig. 6.2 Write an R in the box for the part of the spectrum where radio waves are found. [1] (d) Engineers believe wave generators will be important for supplying electrical energy in the future. These generators have advantages over older methods such as coal-fired power stations. Give one advantage of wave generators for the supply of electrical energy. … …[1]

16 0653/23/O/N/15 © UCLES 2015 7 (a) In some areas of the world large areas of forest are cleared to use the land for agriculture. However, sometimes not all of the trees are cleared from an area. Some of the largest trees are left standing and the areas in between them are cleared. This is called partial deforestation. (i) Describe and explain why partial deforestation is better than complete deforestation for the soil in the forest. … … …[2] (ii) Describe two advantages of partial deforestation compared with complete deforestation for the animal life in the forest. 1 … … 2 … …[2] (b) In some areas of the world raw sewage is discharged into rivers or lakes. This can cause problems for plants and animals that live in the water. (i) Explain why the sewage reduces the amount of dissolved oxygen in the water. … … …[2] (ii) When sewage is added to water it can affect the transparency of the water by making it cloudy. Explain why this reduces the growth of aquatic plants. … … …[2]

17 0653/23/O/N/15 © UCLES 2015 [Turn over 8 A student extracts some copper from a sample of copper carbonate. (a) He adds dilute hydrochloric acid to the copper carbonate until it is all dissolved. Bubbles of carbon dioxide gas appear and a solution of copper chloride is formed. Fig. 8.1 shows the experiment during and after the reaction. dilute hydrochloric acid copper carbonate copper chloride solution Fig. 8.1 (i) Write a word equation for the reaction. + + + [2]

18 0653/23/O/N/15 © UCLES 2015 (ii) The student checks that the gas is carbon dioxide. When the reaction is complete, he collects some of the gas in a pipette. Fig. 8.2 shows how he collects the gas and then passes it through a solution X. solution X reaction mixture gas gas pipette Fig. 8.2 State the name of solution X and describe the effect of carbon dioxide on its appearance. name … effect … …[2]

19 0653/23/O/N/15 © UCLES 2015 [Turn over (b) The student places the copper chloride solution that he has made into the electrolysis cell shown in Fig. 8.3. power supply + – anode cathode copper chloride solution Fig. 8.3 (i) Complete Fig. 8.3 by labelling each electrode to show the product formed. [2] (ii) Choose from the following phrases to complete the sentences about electrolysis. a covalent compound an element a hydrocarbon an ionic compound a mixture Copper chloride solution is the electrolyte because copper chloride is … During electrolysis copper chloride breaks up into simpler substances each of which is … Pure water does not undergo electrolysis because it is … [3]

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21 0653/23/O/N/15 © UCLES 2015 [Turn over 9 Fig. 9.1 shows a small electrical immersion heater for heating a drink in a cup. Fig. 9.1 (a) As the drink is heated, the liquid level in the cup rises slightly. Describe what is happening that causes the liquid level to rise. … …[1] (b) State the main method of thermal energy transfer involved in (i) transferring thermal energy from the hot wire inside the electrical heater to the liquid, …[1] (ii) distributing the thermal energy throughout the liquid. …[1] (c) As the drink gets hot, water vapour escapes from the surface of the liquid before the drink boils. (i) State the name of this process. …[1] (ii) Explain why this happens in terms of the molecules in the liquid. … … …[2]

22 0653/23/O/N/15 © UCLES 2015 10 (a) Fig. 10.1 shows a negatively charged plastic plate mounted on a plastic handle and held by a student. Fig. 10.1 Describe a method of producing a charge on a plastic object. … …[1] (b) Fig. 10.2 shows a charged metal plate mounted on a plastic handle. Fig. 10.2 Explain why the handle should be made of plastic rather than metal. … … …[2]

23 0653/23/O/N/15 © UCLES 2015 (c) Fig. 10.3 shows a circuit diagram for an electric heater, supplied with 12 V from a car battery. 12 V heater Fig. 10.3 (i) When the switch is closed, there is an electric current in the heater. State the meaning of electric current. …[1] (ii) The heater circuit is changed to include a second identical heater and two switches to switch each heater on independently. The heaters must be connected in parallel to work. Complete the circuit diagram below to include both heaters and the switches, connected so that both the heaters work and can be switched on independently. 12 V [3]

24 0653/23/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 0653 COMBINED SCIENCE 0653/23 Paper 2 (Core Theory), maximum raw mark 80 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 0653 23 © Cambridge International Examinations 2015 1 (a) bronchus correctly labelled ; trachea correctly labelled ; larynx correctly labelled ; [3] (b) smaller airway diameter ; presence of mucus obstructing flow ; [2] (c) (i) (12.5 – 5.8) = 6.7 (dm3 / min) ; ( 5.8 6.7 ×100) = 115 or 116(%) ; [2] (ii) breathe more quickly ; take deeper / bigger breaths ; [2] [Total: 9] 2 (a) decreases and endothermic ; [1] (b) hydrogen ; [1] (c) rate of reaction increases / bubbles produced more rapidly / greater temperature change / increases rate of temperature change / reaction will finish faster ; [max 1] (d) copper below hydrogen in the reactivity series ; copper will not displace hydrogen from acid / will not react ; no temperature change ; copper is less reactive than magnesium ; [max 2] [Total: 5] 3 (a) (i) weight / gravitational force ; [1] (ii) newton ; [1] (b) potential (energy)
kinetic (energy) ; kinetic (energy)
potential (energy) ; [2] (c) A to B accelerating ; B to C constant speed ; [2] (d) (distance =) speed × time 9 × 2 ; = 18 (m) ; [2] [Total: 8]

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Page 5 Mark Scheme Syllabus Paper Cambridge IGCSE – October/November 2015 0653 23 © Cambridge International Examinations 2015 7 (a) (i) reduces soil erosion ; roots of trees stabilise soil ; [2] (ii) provides habitats ; provides shelter / protection from sun / rain / predators ; maintains food supply ; [max 2] (b) (i) bacteria / microbes use it ; for respiration ; [2] (ii) (sewage) blocks / reduces light ; light is needed for photosynthesis ; [2] [Total: 8] 8 (a) (i) water in product row ; rest of equation correct ; [2] (ii) limewater ; milky / cloudy ; [2] (b) (i) (cathode) copper ; chlorine ; [2] (ii) an ionic compound ; an element ; a covalent compound ; [3] [Total: 9] 9 (a) (thermal) expansion ; [1] (b) (i) conduction ; [1] (ii) convection ; [1] (c) (i) evaporation ; [1] (ii) molecules gain more energy on heating ; molecules with enough / high / higher energy escape ; [2] [Total: 6] copper carbonate hydrochloric acid copper chloride carbon dioxide water + + +

Page 6 Mark Scheme Syllabus Paper Cambridge IGCSE – October/November 2015 0653 23 © Cambridge International Examinations 2015 10 (a) (i) (charging by) friction / rubbing with cloth / AVP ; [1] (b) plastic is an insulator ; so charge wouldn’t leak away ; OR metal is conductor ; so charge would leak away / earthed by student ; [2] (c) (i) flow of charge ; [1] (ii) workable circuit with additional heater in series / parallel and at least one switch and no short circuit ; two heaters in parallel ; both switches on parallel branches ; [3] [Total: 7]