2022 GMSS Chem Prelims P2

80 Candidate Name Class Index Number ___________________________________________________________ CHEMISTRY Paper 2 6092/02 Sec 4 Express Additional materials : Nil 1 hour 45 minutes 22 Aug 2022 READ THESE INSTRUCTIONS FIRST Write your name, index number and class on all the work you hand in. Write in dark blue or black pen. Do not use staples, paper clips, highlighters, glue or correction fluid. Section A Answer all questions in the spaces provided. Section B Answer all three questions, the last question is in the form either/or. Write your answers in the spaces provided. At the end of the examination, hand in Section A and Section B 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 24. For Examiner’s Use Section A /50 B9 /10 B10 / 10 B11 /10 Total This document consists of 24 printed pages. [Turn over Geylang Methodist School (Secondary) Preliminary Examination 2022

2 GMS(S)/Chem/P2/PRELIM/2022/4E Section A Answer all the questions in this section in the spaces provided. The total mark for this section is 50. A1 The following ionic equations represent some common reactions. A Ba2+ (aq) + SO42− (aq) → BaSO4 (s) B 2Cl− (aq) → Cl2 (g) + 2e− C Cr3+ (aq) + 3e− → Cr (s) D Cu2+ (aq) + 2OH− (aq) → Cu(OH)2 (s) E H+ (aq) + OH− (aq) → H2O (l) F 2I− (aq) + Br2 (aq) → I2 (aq) + 2Br− (aq) Use the letters A, B, C, D, E or F to answer the following questions. You may use the letters once, more than once or not at all. (a) Which equation shows a reaction that forms a white precipitate? ……………………………………………………………………………………….. [1] (b) Which equation shows only reduction? ………………………………………………………………………………………. [1] (c) Which equation shows the neutralisation of a dilute acid by an aqueous alkali? ………………………………………………………………………………………. [1] (d) Which equation shows a displacement reaction? ………………………………………………………………………………………. [1] [Total: 4]

3 GMS(S)/Chem/P2/PRELIM/2022/4E A2 A sample of black ink contains a mixture of red, blue and yellow dyes. Usually, the solvent used to separate the dyes in black ink is a mixture of ethanol and water. The coloured dyes have different R f values in solvents with different compositions of ethanol as shown in the graph below. (a) Using evidence from the graph, predict the colours of the separated spots observed when the solvent used consists of 40% ethanol in the mixture. ……………………………………………………………………………………. [1] (b) State the Rf value of blue dye on the chromatogram when the solvent is a mixture of 32 cm3 of ethanol and 168 cm3 of water.