BBSS Prelim P2

CHEMISTRY 6092/02 Paper 2 20 August 2024 0820-1005h 1 hour 45 minutes Candidates answer on the Question Paper. No Additional Materials are required. READ THESE INSTRUCTIONS FIRST Write your name, index number and class in the spaces provided at the top of this page. Write in dark blue or black pen. You may use an HB pencil for any diagrams or graphs. Do not use staples, paper clips, highlighters, glue or correction fluid. Section A Answer all questions. Write your answers in the spaces provided. Section B Answer one question. Write your answers in the spaces provided. 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. A copy of the Periodic Table is printed on page 26. The use of an approved scientific calculator is expected, where appropriate. For Examiner’s Use Section A / 70 Section B / 10 Total / 80 This document consists of 26 printed pages. Name: ………………………………………. Index No: ……… Class: ……..… Bukit Batok Secondary School GCE O LEVEL PRELIMINARY EXAMINATIONS 2024 SECONDARY 4 EXPRESS

BBSS/O PRELIM/2024/Sec4E/Chem P2 Applying past knowledge to new situations 2 Section A Answer all questions in the spaces provided. The total mark for this section is 70. 1 The following article featured in a newspaper describes how increasing global temperatures due to global warming, grounding planes at the airport. Fig. 1.1 (a) A student explained that the increase in temperature leads to fewer molecules per unit volume. Explain, using Kinetic Particle Theory, how cooler periods of the day allow more lift for the airplane to take off. …………………………………………………………..……………………………… …………………………………………………………..……………………………… ........................................................................................................................ [2]

BBSS/O PRELIM/2024/Sec4E/Chem P2 Applying past knowledge to new situations 3 (b) Environmental groups think that the shrinking of the ice caps is the result of global warming. Satellite images are used to show the area of Arctic Sea ice as shown in Fig. 1.2. Fig. 1.2 (i) Give one consequence of the reduction of Arctic Sea ice. ………………………………………………………………………..……..…… ………………………………………………………………………………... [1] (ii) Describe one possible source of global warming that has led to the reduction of Arctic ice. ………………………………………………………………………..……..…… ………………………………………………………………………………... [1] (iii) Scientists are currently developing a process called carbon capture and storage (CCS). This will reduce the problem of global warming. There are three main steps to CCS. Firstly, carbon dioxide is trapped and separated from other gases produced in coal-powered electricity plants. The captured carbon dioxide is transported to a storage location. The carbon dioxide is then stored far away from the atmosphere (underground or deep in the ocean). Suggest one reason why some scientists do not support the use of CCS. Use the information above to help you answer. ………………………………………………………………………..……..…… ………………………………………………………………………………... [1] [Total: 5] outline of area covered by Arctic Sea ice in 2000 area covered by Arctic Sea ice in 2012

BBSS/O PRELIM/2024/Sec4E/Chem P2 Applying past knowledge to new situations 4 2 Titanium (melting point of 1688 °C) can be extracted from its ore, rutile. Fig. 2.1 shows how titanium metal is extracted from rutile. Fig. 2.1 (a) Using the information provided, arrange carbon, magnesium and titanium in increasing order of reactivity, least reactive first. ……..……………………………………………………………………………….… [1] (b) Describe an example of recycling in the extraction of titanium. …………………………………………………………………………………………… ......................................................................................................................... [1] (c) Explain why an atmosphere of argon must be used in reactor 2. …..……………………………………………………………………………….………. ……..……………………………………………………………………………….… [1] (d) Describe how the titanium produced in reactor 2 can be separated from magnesium chloride. …………………………………………………………………………………………… …………………………………………………………………………………………… ......................................................................................................................... [2] [Total: 5]

BBSS/O PRELIM/2024/Sec4E/Chem P2 Applying past knowledge to new situations 5 3 (a) The Haber Process for the production of ammonia is one of the most important industrial process. Which of the following statements about this process are true and which are false? Put a tick (√) in one box in each row. true false An iron catalyst is used. The reaction is reversible and so the conditions must be chosen carefully to give the best yield. A good yield of ammonia is obtainable even without the use of high pressure. Nitrogen from the air is converted into a substance from which nitrogenous fertilisers can be easily produced. [2] (b) Ammonia is made from nitrogen. Nitrogen can be converted into ammonium and nitrate ions. Various tests are conducted using solutions A, B and C to identify compounds of ammonium and nitrate. Complete the following table with respect to solutions A, B and C. [5] Solutions tests observations identity of substance A (i) pungent gas evolved which turns damp red litmus blue ammonium sulfate (ii) white precipitate formed is insoluble in nitric acid B sodium hydroxide is added to B, until in excess (iii) copper(II) nitrate (iv) pungent gas evolved which turns damp red litmus blue C aqueous lead(II) nitrate is added to C yellow precipitate formed (v) [Total :7]

BBSS/O PRELIM/2024/Sec4E/Chem P2 Applying past knowledge to new situations 6 4 A sample of ink contains a mixture of red, blue, and yellow dyes. To separate the dyes in the ink, the solvent used is a mixture of water and ethanol. The Rf values of the coloured dyes in solvents with different percentage of ethanol present are shown in Fig. 4.1. Fig. 4.1 (a) Using the graph, explain why a pure solvent of either water or ethanol cannot be used to separate the dyes in the ink. …………………………………………………………………………………………… …………………………………………………………………………………………… …………………………………………………………………………………………… ......................................................................................................................... [2] (b) A mixture of water and ethanol was used to separate a sample of this ink. Only one spot was formed on the chromatogram. Explain why it cannot be concluded that the ink sample is a pure substance. …………………………………………………………………………………………… ......................................................................................................................... [1]

BBSS/O PRELIM/2024/Sec4E/Chem P2 Applying past knowledge to new situations 7 (c) What is the Rf value of the blue, red and yellow dyes when a solvent mixture containing 80 cm3 ethanol and 120 cm3 water is used in the chromatography? Rf value of blue dye ………. Rf value of red dye ………. Rf value of yellow dye ………. [2] (d) Is the solvent mixture in (c) appropriate to be used if required to separate the 3 dyes? Explain why. …………………………………………………………………………………………… ......................................................................................................................... [1]