LVSS PRELIM 2023 4NA SCI CHEM P4

LOYANG VIEW SECONDARY SCHOOL Preliminary Examination 2023 Secondary Four Normal (Academic) CANDIDATE NAME : ……………………………………………………………….......... CLASS : …………………. INDEX NUMBER : ……………. SCIENCE (CHEMISTRY) 5105/04 Paper 4 3 Aug 2023 Papers 3 and 4: 1 hour 15 minutes Candidates answer on the Question Paper. No Additional Materials are required. READ THESE INSTRUCTIONS FIRST Write your name, class and index number on all the work you hand in. Write in dark blue or black pen on both sides of the paper. You may use an HB pencil for any diagrams or graphs. Do not use staples, paper clips, highlighters, glue or correction fluid. Answer all questions in Section A and any two questions in Section B. The use of an approved scientific calculator is expected, where appropriate. In calculations, you should show all the steps in your working, giving your answer at each stage. You are advised to spend no more than 30 minutes on Paper 3. You may proceed to answer Paper 4 as soon as you have completed Paper 3. A copy of the Periodic Table is printed on page 11. At the end of the examination hand in your answers to Paper 3 and Paper 4 separately. The number of marks is given in brackets [ ] at the end of each question or part question. Setter: Mdm Elvina Abu Hasan For Examiner’s Use Section A / 14 Section B / 16 Total / 30 This paper consists of 11 printed pages.

2 Section A Answer all the questions in the spaces provided. 1 The positions of 8 elements in the Periodic Table are shown in Fig. 1.1. The letters A to H do not represent the chemical symbols of the elements. Fig. 1.1 (a) Which element, A to H, forms an ion with a charge of +2? ……………………………………………………………………………………......[1] (b) Explain why element H is unreactive? ……………………………………………………………………………………......[1] (c) An atom of element X has an electronic structure of 2,7. Which element, A to H, will have properties most similar to X? ………………………………………………………………………………...…….. [1] [Total: 3] 2 Reacting an acid with a base is a common method of preparing salts. This is known as an acid-base reaction. Table 2.1 gives details of three salts that can be prepared by acid-base reactions. Table 2.1 salt formula relative formula mass, Mr copper(II) sulfate CuSO4 160 magnesium nitrate Mg(NO3)2 sodium sulfate Na2SO4 (a) Use data from the Periodic Table to complete Table 2.1 by calculating the relative formula mass, Mr, of magnesium nitrate and sodium sulfate. [2]

3 (b) Calculate the mass of 0.5 mol of magnesium nitrate, Mg(NO3)2. mass of magnesium nitrate = ……………………….. g [1] (c) (i) Identify the acid and base required to produce sodium sulfate. acid ………………………………………………………….. base .…………………………………………………… [1] (ii) At the end of the reaction between the acid and base from (c)(i), a solution of sodium sulfate is produced. Describe how pure and dry crystals of sodium sulfate can be obtained from its solution. ……………………………………………………………………………………. ……………………………………………………………………………………. ……………………………………………………………………………………. ………………………………………………………………………………... [2] (iii) State the pH of a pure solution of sodium sulfate. ...……………………………………………………………………………… [1] [Total: 7]

4 3 Some of the substances found in the exhaust fumes of a motorcar are shown in Fig. 3.1. Fig. 3.1 (a) Complete Table 3.1 using the names of the substances shown. Each substance can be used only once. Table 3.1 description name of substance a greenhouse gas causes acid rain a noble gas [2] (b) (i) Carbon monoxide is a toxic gas. Explain why carbon monoxide is harmful to human beings. ……………………………………………………………………………………. …..……………………………………………………………………………. [1] nitrogen steam nitrogen dioxide hydrocarbon argon oxygen carbon dioxide carbon monoxide

5 (ii) Fig. 3.2 shows a water heater. Fig. 3.2 Carbon monoxide can be formed when some of the air holes in a water heater get blocked. Explain why this is so. ……………………………………………………………………………………. …..………………………………….…………………………………...……. [1] [Total: 4] combustion products hot water out gas burning in air cold water in air holes

6 Section B (16 marks) Answer any two question in the spaces provided. Write your answers in the spaces provided. 4 Fig. 4.1 shows how iron is extracted in a blast furnace with coke and limestone. Fig. 4.1 (a) (i) State the purpose of adding limestone to the blast furnace. …..……………………………………………………………………………. [1] (ii) The chemical equation below shows the reaction between iron( III) oxide and carbon monoxide that occurs in the blast furnace. Balance the chemical equation by writing the correct numeral s in the blanks provided. …..… Fe2O3 + …….. CO → …..… Fe + …..… CO2 [1] (b) An experiment was set up to investigate the rusting of iron. Five identical iron nails, each weighing 5 g, were used. Each nail was given a different treatment. The nails were left outside in the air for ten weeks, and then reweighed. The results are shown in Table 4.1. Table 4.1 nail treatment mass at start / g mass after ten weeks / g P covered in grease 5.0 5.2 Q coated with zinc 5.0 5.1 R painted 5.0 5.3 S plastic coated 5.0 5.0 T untreated 5.0 6.3

7 (i) State the conditions required for iron to rust. ………….…………………………………………………………………….. [1] (ii) Bicycle frames are made from steel which is an iron alloy. Based on the results in Table 4.1, suggest which treatment gives the best protection against rusting for the frames and explain why. ……………………………………………………………………………………. ……………………………………………………………………………………. ………….…………………………………………………………………….. [2] (iii) Steel is an alloy which contains some carbon atoms mixed with iron atoms. The diagram below shows the arrangement of atoms in steel. Fig. 4.2 Using the diagram shown, explain why steel is harder than pure iron. ……………………………………………………………………………………. ……………………………………………………………………………………. ………….…………………………………………………………………….. [2] (c) Aluminium is a metal which does not rust. It can be recycled many times without losing its properties. State another advantage of recycling aluminium metal. ……………………………………………………………………………………….. [1] [Total: 8]

8 5 Fluorine, chlorine and bromine are Group VII elements found in the Periodic Table . They are also commonly known as halogens. Halogens exist as diatomic molecules. (a) State the meaning of ‘diatomic’. ……………………………………………………………………………………….. [1] (b) The arrangement of electrons in bromine is 2,8,18,7. Explain why bromine is found in Group VII and Period 4 of the Periodic Table. Group VII …………………………………………………….………………………… .……………………………………………………………….……………………….… Period 4 ………………………………………………………………………………... .……………………………………………………………….……………………… [2] (c) Draw a ‘dot and cross’ diagram to show the arrangement of all the electrons in a molecule of fluorine. [2] (d) (i) Halogens can undergo displacement reaction. Put a tick (✓) if there is a reaction between chlorine and aqueous solutions of sodium chloride, sodium bromide and sodium iodide. halogen reaction with sodium chloride reaction with sodium bromide reaction with sodium iodide chlorine [1] (ii)