YCKSS Sc(Chem) Prelim

BP - 329 Name: lndex Number: Class: YIO CHU KANG SECONDARY SCHOOL O.LEVEL PRELIMINARY EXAMINATION 2024 SECONDARY FOUR EXPRESS scrENcE (PHYSTCS / CHEMTSTRY) Paper 1 Additional Material: Optical Answer Sheet (OAS) 5086/01 t hour 23 August 2024 (Friday) READ THESE INSTRUCTIONS FIRST Write in soft pencil on the OAS. Do not use staples, paper clips, glue or correction fluid. Write your name, index number and class on the OAS in the spaces provided. There are fofi questions on this paper. Answer all questions. For each question there are four possible answers A, B, c and D. Choose the one you consider conect and record your choice in soft pencil on the separate OAS Read the instructions on the OAS very carefully. Each conect answer will score one mark. A mark will not be deducted for a wrong answer. Any rough working should be done in this question paper. The use of an approved scientific calculator is expected, where appropriate. The colours of some common metal hydroxides are given on page 8. A copy of the Periodic Table is printed on page 9. For Examiner's Use 40 Setters: Mdm Toh Lee Wah This document consists of 9 printed pages. I

BP - 331 1 An acidic gas T is denser than air and insoluble in water. Which method(s) can be used to collect the gas? 1 32 A B c D A B c D 2 only 3 only 1and2 2and3 2 Bromine is a liquid at 20 'C. What is the melting point and boiling point for bromine? melting poinv 'C boiling poinY 'C A B c D -22 -8 -7 25 -3 -33 59 103 3 What changes occur when a gas at 200 "C becomes a solid at -5'C? 4 What ions are present in iron([l) sulfate, Fe2(SO4)3? Fe2' and SO+2- Fe2* and SO+3- Fe3* and SOr2- Fe3' and SOr} separation of Particles energy of particles attractive forces between particles A B c D decreases decreases increases increases decreases increases decreases increases increases decreases increases decreases I m I

BP- 332 5 The diagram shows the molecule ethyl propanoate. o // cH3-cH2 - c \ o-GH2-CHs How many bonding pairs of electrons are there in the molecule? A B c D A B c D 7 16 17 20 6 Aqueous solution R is gradually added to aqueous solution S. The changes in pH are shown on the graph. pH 11 13 12 1l r0 9 I 7 E I 3 2 1 0 10 rt 20 25 30 35 10 45 50 volume of R added/ cm3 What are R and S? R S A B c D aqueous ammonia ethanoic acid hydrochloric acid sodium hydroxide ethanoic acid sodium hydroxide aqueous ammonia hydrochloric acid 7 which substance does not produce coppe([) sulfate when added to dilute sulfuric acid? copper copper(tr) carbonate copper(tr) hydroxide coppe(Il) oxide 0 5 I

BP - 333 8 Which element contains the least number of atoms in 1 g? carbon iodine iron orygen I A B c D Aqueous sodium hydroxide and aqueous ammonia were added separately to two different aqueous solutions each containing the same metatlic ion. ln both cases, a white precipitate was formed which dissolved when excess sodium hydroxide or aqueous ammonia was added. What is the ion? Ca2' Cu2* K- Zn2t {O A simplified version of the Periodic Table shows four elements with the code lefters, W, X, Y and Z. Which of the following statements is conect? A W is a metal while X, Y and Z are non-metals. B W and X are solid but Y and Z are gases at room temperature. C W and X are in the same group with the same number of electron shells. D W and X form an ionac compound while Y and Z a form covalent compound 11 Which element in the table is an alkali metal? melting point t"c density i g/cm3 A B c D -39 -7 98 1093 '13.60 3.10 0.97 8.92 A B c D w x Y f-] I z I I

BP - 334 12 What are the oxidation states of chlorine in ClzO and C/O+'? -2 and -1 +1 and +3 +'l and +7 +2 and +8 13 Experiments were carried out to determine the positions of metals X, Y and Z in the reactivity series. The table shows the results. test metal X metal Y melal Z reaction between metal and hydrochloric acid effervescence no visible observation effervescence heating the metal oxide with carbon metal oxide reduced metal oxide reduced metal oxide not reduced What is the order of reactivity of these metals? most reactive ----------> least reactive A B c D z X X X z z X Z 14 Chromium is placed between zinc and iron in the reaclivity series. Which metal reduces the oxide of chromium? copper iron lead magnesium 15 During a chemical reaction, the temperature of the reaction mixture increased. Which row conectly describes the type of energy change and the transfer of heat during this reaction? type of energy change A B c D endothermic endothermic exothermic exothermic absorbed from sunoundings lost to surroundings absorbed from sunoundings lost to surroundin gs A B c D A B c D transfer of heat

BP - 335 16 Which of the following changes will increase the speed of reaction between one mole of gas T and two moles of gas U? a decrease in temperature a decrease in the mass of catalyst an increase in the particle size of catalyst a decrease in the volume of the reaction flask 17 Curve I is obtained by observing the decomposition of 100 cm3 of 1 mol/dm3 aqueous hydrogen peroxide, catalysed by manganese(tV) oxide. ZHzOz(aQ) -+ 2HzO 171 + Oz(9) il volume of oxygen formed time Which alteration to the conditions will produce curve ll? A adding some 0.'1 mol/dm3 aqueous hydrogen peroxide B lowering the temperature C using a better catalyst D using less manganese(Iv) oxide 1g 80.0 cm3 0f a sample of air is trapped in a syringe. The air is slowly passed over heated iron in a tube until there is no further decrease in volume. tron A B c D t 80 cm3 of air heat When cooled to the original temperature, what volume of gas remains? 16.8 cm3 40.0 cm3 60.0 cm3 63.2 cm3 A B c D

BP - 336 19 Which substance has a main constituent that contains only one carbon atom per molecule? bitumen kerosene naphtha natural gas 20 Which statement about vegetable oil and margarine is conect? A Both vegetable oil and margarine are liquids at room temperature. B Margarine has a higher melting point than vegetable oil. C Vegetable oil has fewer carbon-carbon double bonds than margarine D Vegetable oil is made from margarine by hydrogenation. A B c D I

BP- 339 lndex Number: Class: YIO CHU KANG SECONDARY SCHOOL PRELIMINARY EXAMINATION 2024 SECONDARY FOUR EXPRESS scrENcE (cHEMISTRY) Paper 3 5086 & 5088/03 t hour 15 minutes 28 August 2024 (Wednesday) No Additional Materials are required. READ THESE INSTRUCTIONS FIRST Write your name, index number and class on the cover page. Write in dark blue or black ink. You may use a soft pencil for any diagrams or graphs. Do not use staples, paper clips, glue or correction fluid. Section A Answer all questions in the spaces provided Section B Answer any one question in the spaces provided The number of marks is given in brackets [ ] at the end of each question or part question At the end of the examination, fasten all your work securely together. A copy of the Periodic Table is on page 16 For Examiner's Use Section A lss Section B lto Total las Setter: Mdm Toh Lee Wah This document consists of 15 printed pages and 1 blank page Name: I

BP - 340 ,| SECTION A Answer all questions in the spaces provided. Name the apparatus best used to carry out the following procedures. (a) Mix 250 cm3 each of two solutions. t11 (b) Measure the freezing point of a liquid t1l (c) Measure the time taken to melt 10.5 g of a solid. . .... ..11I (d) Collect and measure 20 cm3 of ammonia gas .........t1I [fotal: 4] Table 2.1 shows some information about four different substances, A, B, C and D when heated. Complete Table 2.1 by identirying whether substances, A, B, C and D is an element, compound or mixture. Table 2.1 substance melting poinV 'C colour other information element, compound or mixture A -10 to -6 green A colourless gas is given off. A greenish-white solid is left behind. Another gas condenses into water droplets on the sides of the test tube. 105 white It melts into a colourless liquid and tums brown on further heating. Finally, a black residue is left behind. 115 yellow It melts into a dark orange liquid. Upo