208 aozz tad BOTSWANA EXAMINATIONS COUNCIL Botswana General Certificate of Secondary Education CANDIDATE NAME 7 CENTRE ] CANDIDATE. NUMBER l NUMBER SCIENCE: DOUBLE AWARD 0569/03, Paper 3 Theory October/November 2020 2hours Candidates answer on the Question Paper. No Additional Materials are required READ THESE INSTRUCTIONS FIRST Write your candidate name, Centre number and candidate number in the spaces provided at the top of this page. Write in dark blue or black pen. You may use a soft pencil for any diagrams, graphs or rough working, Do not use staples, paper clips, highlighters, glue or correction fluid, DO NOT WRITE IN ANY BARCODES. ‘Answer all questions. Write your answers in the spaces provided on the Question Paper. ‘The number of marks is given in brackets [ ] at the end of each question or part question. ‘You may lose marks if you do not show your working or if you do not use appropriate units. You may use a calculator. A copy of the Periodic Table is printed on page 20. For Examiner's. Use el~alolalale|ry|= 10 "1 12 13 14 Total This document consists of 17 printed pages and 3 blank pages. © BEC 2020 [Turn over2 For exeminers 1 A shopkeeper lifts a bag of sugar of 12.5kg from the floor to a shelf of height 1.2m in 8.56s. (a) State the main energy change that occurs on the bag as it is being lifted. to (2) (b) State the relationship between work and energy. (c) Calculate (i) the work done in lifting the bag of sugar, (g= 10N/kg) 268 work done = J 2] (ii) the power developed by the shopkeeper. power = Ww 12) § © BEC 2020 0569103/0N20eae 2 sariers 2 Fig. 2.1 shows two rods of the same size placed in hot water. One rod is made of steel and the other is made of wood. steel rod, wooden rod hot water Fig. 2.1 (a) State the rod that would feel hotter when the top of each rod is touched after 5 minutes. Explain your answer. 204 rod explanation (] (b) State two ways in which thermal energy is being lost from the hot water. 1 2. (2) (c) Describe how the thermal eneray is transferred through a solid 5 [2 BEC 2020 oss10a10120 [Turn over4 3 Fig. 3.1 shows sound waves produced by a loudspeaker. Cis the compression and R is the rarefaction. I Fig. 3.1 ATS loudspeaker (a) State the type of waves produced by the loudspeaker. & {b) On Fig. 3.1, mark the wavelength of the wave. {c) (i) 75 complete waves pass a point in one second, State the frequency of the wave. frequency = (ii) The wavelength of the wave is 4.2m. Calculate the speed of the wave. q speed = © BEC 2020 os690s/01N20 M1) Hz [1] ..m/s [2] For lexemners Use’ie ecomnars 4° Fig. 4.1 shows an electric circuit A battery with a 12.0V electromotive force is connected in series with a 2.0 resistor, resistor R and meter P. 12.0V —--4—— 7 R 2.00 Fig. 4.1 264 {a) State the meaning of 12.0 electromotive force. (] {b) Meter P is used to measure the rate of flow of charge State the name of meter P. (1 (c) A voltmeter connected across R reads 4.0V. Calculate the potential difference across the 2.0. resistor. A027 potential difference = Vt] (a) Determine the resistance of resistor R. resistance of R = 2B] i (e) The 2.02 resistor is now connected in parallel with resistor R. State the effect of this change on the reading of meter P. Explain your answer. effect explanation (2) © BEC 2020 os6a/03/01N720 [Turn over5 & 6 Fig, 5.1 shows a simple alternating current generator. to cathode ray oscilloscope Fig. 5.1 (a) State the name of component X. (1) (b) Describe how the generator produces a current. (3) (c) Fig. §.2 shows how the output voltage varies with time. time! voltage Fig. 5.2 The speed of rotation of the coil is doubled. ‘Suggest the effect this will have on the amplitude and the frequency of the waveform. amplitude frequency ....... [2] © BEC 2020 ‘0568/0a/0m/20 lexamners7 poe 6 Fig. 6.1 shows a sign placed on the door of a room (a) State the meaning of the sign. (1) (b) State any two precautions to be taken when entering the room. 1 2 (2) © Bec 2020 56910310120 [urn overexaminers Use 7 Fig. 7.1 shows an outline of the Periodic Table. The letters S, T, U, V, W, X, Y and Z are not symbols of elements. Vv ] Fig. 7.1 Use Fig. 7.1 to answer the questions. a Choose a letter that represents an element that (a) ‘is likely to be used as a catalyst. (1) (b) bums with a ‘pop’ sound a0 (c) will vigorously react with water. (1) (d) reacts with non-metals to form a covalent compound. (1) (e) reacts with sodium to form a compound containing two atoms of sodium for every atom of the element. 3 (1) (f) is an unreactive element. f] © BEC 2020 0s6903/0N20204 Ao 8 Iron(III) nitrate solution reacts with ammonium hydroxide solution to form iron(II) hydroxide precipitate and ammonium nitrate solution. (a) An incomplete equation for the reaction is shown. Fe(NOs)s(....) +... NHAOH(.....) > Fe(OH)a(.....) + Go) Complete the equation by: * writing the missing compound, ‘+ writing the state symbols of all the compounds, ‘+ balancing the equation (b) Calculate the relative molecular mass of iron(II) hydroxide, Fe(OH). IAs Fe, 56; O, 16; H, 1] relative molecular mass = (c) Iron(IIl) nitrate solution reacts with aqueous potassium iodide, KI. solution. The iron(III), Fe**, ion changes to iron(II), Fe2*, ion. (i) Describe a test that can be carried out to confirm the presence of the Fe** ions and state the result of the test. test result [3] (1 ‘al State the name of the process that makes Fe* ions to change to Fe® ions. (iii) Give a reason for your answer in (¢)(ii). (1) (1) examiners Us © BEC 2020 os69103/0"N20 [Turn over10 For examiners ‘Use 9 (a) An impure sample of iron(II) oxide has a mass of 2.489. The sample reacts completely with 200 cm? of 0.208 mol/dm? of dilute hydrochloric acid (i ) Calculate the number of moles in 200.cm® of 0.208 mol/dm* dilute hydrochloric acid, (2) ‘The equation for the reaction is shown. FezOs(s) + 6HCl(aq) > 2FeCh(aq) + 3H-0(9) z Use your answer to (a)(i) and the equation to calculate the number of moles of iron(IIl) oxide, Fe:Os, that reacted with the acid moles = (2) (b) (i) The relative molecular mass of Fe-Os is 160. Use your answer to (a) to calculate the mass of iron(II) oxide, FezOs, that reacted with the acid. 5 mass = re Use your answer to (b)(i) to calculate the percentage purity of the iron(II) oxide. percentage purity = pI ©BEC 2020 os69/02/01Ns20a Exorinars 40 Pentane, CsH:2, is an organic compound found in petrol. It has three structural isomers. o (a) (i) State the name of the homologous series to which pentane belongs. (1) (ii) Write the general molecular formula for this homologous series. a | (b) One of the structural formulas of the isomers of CsH:2 is shown. H HH HH Ltt tid eer HH H HOH 264 Draw two other isomers of CsHy2. (2) (c) Pentane burns in oxygen to form carbon dioxide and steam. The equation for the reaction is shown. CsHr2(l) + 802(g) + 5CO2(g) + 6H20() ‘027 i) State another type of reaction that pentane undergoes. [1] (ii) State the name of one source of CsH:2. (1) (ili) Carbon dioxide dissolves in water to form an acidic solution. ‘Suggest the pH of the solution. Explain your answer. suggestion explanation 2 BEC 2020 0569/03101N20 [Turn over12 For exomners ‘Use (d) The equation represents the cracking of pentane CsHi, pentane — ethene +Z (i) State the name of substance Z. 1 (ii) Draw a ‘dot'(*) and ‘cross'(x) diagram to show the bonding in a molecule of ethene, C:Hs. Show electrons in the outer shells only. 264 (2) 3 (© BEC 2020 osear0s/01N20413 For Exominers 41 Fig. 11.1 shows the structure of one type of a white blood cell. Fig. 14.4 {a) State the function of the cell shown in Fig. 11.1 (1) 264 (b) State two ways in which the structure of the cell shown in Fig. 11.1 differs from that of a palisade cell from a leaf. 1 2. (2) (c) The virus which causes AIDS attacks and destroys white blood cells after entering the human body. (i) State the name of the virus that causes AIDS. (11 (ii) State two ways in which this virus can be transmitted from an infected person to another person. A027 ‘i 2 (2) © BEC 2020 osss/oa/0n/20 [Turn overz 3 4 PAGS gall bladder \ BZ \ Fig. 12.4 (a) State the names of the parts labelled P and Q on Fig. 12.1 P Qa (b) State the function of the part labelled R. (c) Gastric by-pass is a surgical operation done to reduce the size of the stomach. ‘Suggest how this operation helps an obese person to lose weight. (d) Describe the effect of removing the gall bladder on the digestion of food. BEC 2020 056903/01N20 (2) [1] [3] (2) lexaroners15 13 A farmer adds a nitrate fertiliser on a field. (a) Describe how nitrate ions are absorbed by plants from the soil {b) Fig. 13.1 shows the effect of the fertiliser on plant growth B c . height of plant | D | increasing amount of fertiliser added to soil | Fig. 13.41 t (i) Explain the shape of the graph from A to B. ‘The farmer increases the amount of fertiliser and notices that from C to D some plants started dying, Explain the likely causes of the death of the plants. 2 BEC 2020 os69103/01N20 examners "Use (3] (41 Al [Turn over268 g 16 14 Lactase from a fungus is used to produce lactose-free milk. Fig. 14.1 shows how the rate of enzyme reaction is affected by temperature. rate of reaction 02040 6080100 temperature/°C. Fig. 14.1 (a) (i) Define the term enzyme. (ii) State one property of enzymes, other than being temperature sensitive. (b) Explain the shape of the graph from A to B, at B and from B to C. AtoB Btoc (c) On Fig. 14.1, draw a curve you would expect if lactase from a human being was used, rather than the lactase obtained from a fungus. © BEC 2020 (0569/03/01N/20 (2) 0) fo} [2] examiners “ise268 027 © BEC 2020 17 BLANK PAGE osesi03/01N2020 on pw) wy | sa a | ww | md | dN | od | ho « = TP me) on) col) wma) wom) waa?) we) wma wn’) cn amd) ea se em | en] | | se] mer] | eat | ent a) caine PONE Goel ge (sf en teed tenet eae ead || seuss power 1-28, - ee 44 pean ena pes |e | ems [gre [ren Fl up | wood | te | ad | mt | 6H | ony so | we | @ | ow | oo | ow ea aI =} se} @] *} __e| = et a ed en won x a as | us ou | po by au 1s ew | |i |i | om | mw | = = =) 8] | "| 8) a] san a ee wom" | ” as wv | |] & | w no a) * jw fw |e | ow |» |] « ee a] * st Ca uy ty ee ea wo Ww Ss d Is Ww eN ° es | «|e |e @ wo 7 7 7 7 o = ee ee os oe eae: | ce | Nee ero) a) n | e | a {aw fnfado Le wow 7 tt | oH 4 , Lo ofm{[nufalta |u| u i ‘dnoip Squowiala auf Jo 21921 B1poed SyL A33HS Viva sew os69/02/01N20 © BEC 2020