2022 PLMGS Chem Prelims P2

1 CANDIDATE NAME CLASS CLASS INDEX NO CENTRE NUMBER S INDEX NO CHEMISTRY 6092/02 Paper 2 19 August 2022 1 hour 45 minutes Candidates answer on the Question Paper. No Additional Materials are required. READ THESE INSTRUCTIONS FIRST Write your name and index number 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 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. Answer all questions 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. For Examiner’s Use Section A Section B 7 8 9 E/O Total A copy of the Periodic Table is printed on page 2. The use of an approved scientific calculator is expected, Paya Lebar Methodist Girls’ School (Secondary) Preliminary Examination 2022 Secondary 4 Express

2 where appropriate. This document consists of 25 printed pages[Turn Over

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4 Section A Answer all the questions in this section in the spaces provided. The total mark for this section is 50. A1 The formulae of some elements are given in the following list. Al Cu Fe H2 Na O2 Mg Choose elements from the list to answer the questions. (a) Which elements in the list are transition metals? (b) Which element is commonly used as a sacrificial protection metal to prevent rusting? (c) Choose one element which shows both metallic and non-metallic character. (d) Which element can be extracted from its ore by heating with carbon? (e) Which element can react with steam but not cold water? [5] [Total: 5] A2 This question is about elements in Group V of the Periodic Table. (a) The table shows some properties of the Group V elements. [Turn Over

5 element density at room temperature in g/cm3 melting point in 0C nitrogen 1.17 x 10-3 -210 phosphorus 2.34 44 arsenic 5.73 antimony 631 bismuth 9.80 272 Use the information in the table to: (i) Predict the density of antimony. [1] (ii) Suggest why it is difficult to predict the melting point of arsenic. [1] (b) The structure of two compounds of phosphorus, R and S, are shown. (i) Explain in terms of structure and bonding why compound R has a high melting point and compound S has a low melting point. [4]

6 compound R compound S (ii) Draw the ‘dot and cross’ diagram for compound S. Show only the outer most shell electrons. [2] (c) An oxide of phosphorus has the formula P4O10. (i) Calculate the percentage of phosphorus in P4O10. [2] [Turn Over

7 (ii) State the oxidation state of phosphorus in the compounds in the table below. Compound Oxidation state of phosphorus compound S P4O10 [2] [Total: 12] A3 A student investigated the reaction of iron with chlorine using the apparatus shown in Fig. 3A.

8 Fig. 3A The word equation for the reaction is iron + chlorine → iron chloride The student made several measurements and recorded her results in Table 3B. Mass in g glass tube 51.56 glass tube and iron 56.04 glass tube and iron chloride 64.56 Table 3B (a) Explain why the chlorine gas must be continued to pass through the apparatus until the iron has cooled down. [1] (b) (i) Calculate the mass of iron and chlorine in iron chloride. [2] chlorine gas in excess chlorine gas out iron heat glass tube [Turn Over

9 mass of iron = ……………………. g mass of chlorine = ……………….. g (ii) Calculate the simplest whole number ratio of number of moles of iron : number of moles of chlorine atoms in iron chloride [2] number of moles of iron : number of moles of chlorine atoms = …….. : ………... (iii) Hence, determine the balanced chemical equation for the reaction. [1] [Total: 6] A4 In Experiment 1, magnesium ribbon reacts with dilute hydrochloric acid. Mg (s) + 2HCl (aq) → MgCl2 (aq) + H2 (g)

10 Fig. 4A shows the volume of hydrogen gas produced at 200C as the reaction proceeds for Experiment 1. The acid is in excess. Fig. 4A (a) Based on the information from Fig. 4A, calculate the mass of magnesium that was used in the reaction. [2] Experiment 1 [Turn Over