2020 SNGS Y4IP EOY P2

This document consists of 20 printed pages [Turn over Name: _________________________ ( ) Class: ___________ YEAR FOUR INTEGRATED PROGRAMME END-OF-YEAR ASSESSMENT __________________________________________________________________________ CHEMISTRY Paper 2 2 October 2020 1 h 45 minutes __________________________________________________________________________ READ THESE INSTRUCTIONS FIRST Write your name, register number, and class on all the work you hand in. Write in dark blue or black pen. You may use a soft pencil for any diagrams or graphs. Do not use highlighters, glue, correction fluid or correction tape. Answer all questions. Write all answers on the blanks provided in the question paper. The use of a scientific calculator is expected, where appropriate. You are reminded of the need for clear presentation in your answers. A copy of the Periodic Table is provided on page 2. The number of marks is given in brackets [ ] at the end of each question or part question. The total number of marks for this paper is 80. For Examiner’s Use Section A (50) Section B (30) Total (80)

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3 Section A Answer all the questions in this section in the spaces provided. The total mark for this section is 50. A1 Choose from the following substances to answer the questions below. aluminium sulfate ammonium chloride argon calcium carbonate iodine lead(II) hydroxide manganese(IV) oxide nickel nitrogen dioxide Each substance can be used once, more than once or not at all. List the substance that is (a) in the solid state at room temperature and can be used to lower the activation energy of a reaction, ………………………………………………………………………………………… [1] (b) used to fertilise soil, ………………………………………………………………………………………… [1] (c) added to the blast furnace to remove impurities in the extraction of iron, ………………………………………………………………………………………… [1] (d) amphoteric, ………………………………………………………………………………………… [1] (e) prepared by adding excess metal carbonate to dilute ac id, followed by crystallization, ………………………………………………………………………………………… [1] (f) separated from a mixture by sublimation. ………………………………………………………………………………………… [Total: 6 Marks] [1]

4 A2 Kelly attempted to separate a homogeneous liquid mixture containing three substances that are soluble in each other. The table below shows the melting and boiling points of the three substances. substance melting point / °C boiling point / °C W -114 55 X -95 80 Y 50 340 Kelly carried out fractional distillation and recorded the total volume of distillate collected at various temperatures . She stopped the experiment once the thermometer reached a reading of 85 °C. (a) State the substance(s) remaining in the mixture at the end of this experiment. ………………………………………………………………………………………… [1] (b) Sketch the graph of temperature against total volume of distillate collected as the thermometer’s reading increased from 50 °C to 85 °C. [2]

5 Chromatography was carried out on substance Y and a toxic dye separately using water as the solvent. The results obtained are shown in chromatogram A and chromatogram B respectively. (c) Determine the Rf value of substance Y. Show your working clearly and leave your answer to 2 decimal places. ………………………………………………………………………………………… [1] (d) Does the toxic dye contain substance Y? Explain your answer. ………………………………………………………………………………………… [1] (e) When carrying out chromatography, explain briefly why the start line should be drawn with a pencil and not a pen. ………………………………………………………………………………………… ………………………………………………………………………………………… [Total: 6 Marks] [1]

6 A3 The structure of five chemical substances are shown below. (a) Which of the structure above is an element? ……………………………………. [1] (b) Which of the structure(s) above melt over a range of temperatures? ………………………………………………………………………………………… [1] (c) Which of the following structures is unable to conduct electricity in any state? ………………………………………………………………………………………… [1] (d) State the type of particles present in structure II when it is in the gaseous state. D escribe the arrangement and movement of those particles in the gaseous state. ………………………………………………………………………………………… ………………………………………………………………………………………… [2]

7 (e) In terms of bonding and structure, explain whether structure IV can conduct electricity in the solid state. ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… [Total: 7 Marks] [2] A4 During the extraction of copper, its sulfides are commonly blasted in furnaces with hot air to liberate sulfur dioxide gas as shown in the equation below. Cu2S + O2 → 2Cu + SO2 (a) Describe a test that can be carried out to prove that the gas liberated is sulfur dioxide. Include any relevant observations. ………………………………………………………………………………………… ………………………………………………………………………………………… [2] (b) Is Cu 2S oxidised, reduced or both in the equation above? Explain your answer using oxidation numbers. ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… [3]

8 (c) The furnaces release flue gas that contains mainly air and sulfur dioxide. Since s ulfur dioxide gas is harmful for the environment, it can be removed from the flue gas using a ‘scrubber’ that contains compound X and water. Write a balanced equation to represent the removal of sulfur dioxide by X. ………………………………………………………………………………………… [Total: 6 Marks] [1] A5 Group II elements show similar trends in physical and chemical properties as Group I elements down the group . The trend s of some properties of Group II elements are as shown. Group II elements Trends Mg Down Group II, 1. melting and boiling point decreases 2. reducing power ………………….. 3. ease of Group II carbonate decomposition decreases Ca Sr Ba (a) Fill in the blank above with the most appropriate word. [1] (b) Explain the trend in melting point down Group II in terms of bonding and structure. ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… [2]

9 (c) Predict what wi ll be observed when barium is added to a beaker of water. Include observations from any relevant confirmation test(s) as well. ………………………………………………………………………………………… ………………………………………………………………………………………… [2] (d) Explain the trend in the ease of Group II carbonate decomposition. ………………………………………………………………………………………… ………………………………………………………………………………………… [2] (e) Can strontium be extracted from its oxide using carbon? Explain your answer. ………………………………………………………………………………………… ………………………………………………………………………………………… [1] (f) A student attempted to protect calcium metal from corrosion by attaching a piece of magnesium strip to it via a wire. Will her attempt be successful? Explain your answer. ………………………………………………………………………………………… ………………………………………………………………………………………… [2] (g) Group II elements undergo exothermic reactions with Group VII halogens to form salts. State the chemical formula of the Group VII element that will have the most exothermic reaction with barium.