YCKSS Prelim P2

Name: Index Number: Class: YIO CHU KANG SECONDARY SCHOOL O-LEVEL PRELIMINARY EXAMINATION 2024 SECONDARY FOUR EXPRESS CHEMISTRY 6092/02 Paper 2 1 hour 45 minutes 28 August 2024 (Wednesday) No Additional Materials are required. 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. You may use an HB pencil for any diagrams or graphs. Do not use staples, paper clips, 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. 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. The use of an approved scientific calculator is expected, where appropriate. For Examiner’s Use Section A / 70 Section B / 10 Total / 80 Setter: Mdm Connie Yeo This document consists of 22 printed pages and 2 blank pages.

2 4E PRELIM EXAM 2024 6092/02 Section A [70 marks] Answer all the questions in this section in the spaces provided. A1 The diagram shows part of the Periodic Table. Answer these questions using only the elements shown in the diagram. Each element can be used once, more than once or not at all. Write the symbol for (a) an element which is in Group 14 and Period 3, ..………...….. [1] (b) an element which is used to fill light bulbs and in the manufacture of steel, ……………… [1] (c) an element whose ions in aqueous solution gives a yellow precipitate on reaction with aqueous silver nitrate, ……………… [1] (d) an element which forms an ion of type Y3-, ……………… [1] (e) an element which is a catalyst for the hydrogenation of alkenes, ……..……… [1] (f) two elements which combine to form a compound which causes acid rain. ..……… and ………… [1] [Total: 6]

3 4E PRELIM EXAM 2024 6092/02 A2 The graph below shows how the pH changes when aqueous sodium hydroxide is added slowly to 5.0 cm3 of 0.100 mol/dm3 sulfuric acid until the alkali is in excess. (a) Calculate the concentration of sodium hydroxide solution that completely neutralised 5.0 cm3 of 0.100 mol/dm3 sulfuric acid. concentration = …………………………. mol/dm3 [2] (b) The experiment was repeated using ethanoic acid of the same concentration as the sulfuric acid. Other conditions were kept constant. (i) Deduce the volume of ethanoic acid required for the neutralisation reaction. ……………………………………………………………………………………….. (ii) Explain your answer in (b)(i). ……………………………………………………………………………………….. ……………………………………………………………………………………….. ……………………………………………………………………………………….. [2] volume of sodium hydroxide added / cm3 pH 0.0 7.0 14.0 5.0 10.0 15.0

4 4E PRELIM EXAM 2024 6092/02 A2 (c) Sulfuric acid is a strong acid whereas ethanoic acid is a weak acid. Describe the difference between a strong acid and a weak acid. Include equations to support your answer. ……………………………………………………………………...………………………. ………………………………………………………………………...……………………. …………………………………………………………………………...…………………. ……………………………………………………………………………...………………. [2] [Total: 6] A3 Resistivity is a property that describes the extent to which a material opposes the flow of electric current through it. The lower the resistivity of the material, the more readily electric current can flow through the material, the better its electrical conductivity. The table below shows the resistivity values of three precious metals and carbon. metal resistivity (Ωm) at 20 oC carbon (diamond) 1.00 x 10 12 carbon (graphite) gold 2.44 x 10-8 platinum 1.06 x 10-7 silver 1.59 x 10-8 (a) With reference to their bonding and structures, explain the difference in resistivity between diamond and the precious metals. ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… [2] (b) A student commented that graphite’s resistivity will be similar to diamond’s since they contain the same element carbon. Do you agree with the student’s comment? Briefly explain your reasoning. ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… [1]

5 4E PRELIM EXAM 2024 6092/02 A3 (c) Precious metals sold commercially often have a purity of about 90-99.9%. Explain why precious metals are sold commercially in the form of alloys instead of the pure metal. ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… [2] (d) The resistivity values given in the table are measured at 20 C. Using kinetic particle theory, describe and explain how you would expect the resistivity of the materials to change if the temperature was raised to 40 C. ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… [2] [Total: 7] A4 Alkynes are a homologous series of organic compounds. Alkynes are unsaturated hydrocarbons containing carbon-carbon (C≡C) triple bonds. The table below shows the names, formulae and boiling points of some alkynes. name formula boiling point / oC ethyne C 2H2 84 23.2 butyne C 4H6 8.1 pentyne C 5H8 40.2 (a) (i) Deduce the general formula for alkynes. …………..……………… [1] (ii) Give one other evidence that suggest that the alkynes are a homologous series. ……………………………………………………………………………………….. [1]

6 4E PRELIM EXAM 2024 6092/02 A4 (b) Give the name and full structural formula of the alkyne member with 3 carbon atoms. name : ………………………………………. full structural formula : [2] (c) (i) Name the two products formed when alkynes undergo complete combustion. ……………………….………………………………………………………………. [1] (ii) Ethyne burns with a sootier flame compared to ethene. Do you agree with this statement? Explain your answer. ………………………….……………………………………………………………. ……………………….……….……………………………………………………… [1] [Total: 6]

7 4E PRELIM EX