NYJC Prelim H2 Chem 9729 P3

[Turn Over NANYANG JUNIOR COLLEGE JC 2 PRELIMINARY EXAMINATION Higher 2 CANDIDATE NAME CLASS TUTOR’S NAME CHEMISTRY 9729/03 Paper 3 Free Response September 2025 2 hours Candidates answer on the Question Paper. Additional Materials: Data Booklet READ THESE INSTRUCTIONS FIRST Write your name 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. Answer all questions in the spaces provided on the Question Paper. If additional space is required, you should use the pages at the end of this booklet. The question number must be clearly shown. Section A Answer all questions. Section B Answer one question. A Data Booklet is provided. The use of an approved scientific calculator is expected, where appropriate. 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 1 / 22 2 / 20 3 / 18 4 / 20 5 / 20 Total / 80 This document consists of 28 printed pages. H

2 H2 Chemistry 9729/03 NYJC J2/2025 Prelim Section A Answer all the questions in this section. 1 (a) The pH values of the solutions of four chlorides are given in Table 1.1. Table 1.1 compound pH of 1.0 mol dm−3 solution BeCl2 x NaCl 7.0 AlCl3 3.0 PCl5 1.0 (i) Explain the difference in pH values of solutions of NaCl, AlCl3 and PCl5, in terms of the structures of the chlorides. Include appropriate equation(s) in your answer. [4] (ii) Using the Data Booklet, suggest how the pH value of 1.0 mol dm −3 solution of BeCl2 compares to 1.0 mol dm−3 solution of AlCl3. Explain your answer. [2] (iii) At certain temperatures, aluminum chloride exists as A l2Cl6 molecules. Draw the structure of Al2Cl6. Label the co-ordinate bonds on your structure. [1]

3 H2 Chemistry 9729/03 NYJC J2/2025 Prelim [Turn Over (b) Beryllium, in Period 2, is the only element in Group 2 that shares very similar chemical properties with aluminium which is in Period 3. Describe the similarities in their acid-base behaviour and explain why beryllium oxide reacts similarly like aluminium oxide. Illustrate the reactions of beryllium oxide with equations. [2]

4 H2 Chemistry 9729/03 NYJC J2/2025 Prelim (c) BrCl reacts with benzene in the presence of AlCl3 in an electrophilic substitution reaction to produce bromobenzene. (i) Explain why bromobenzene is made in preference to chlorobenzene during the reaction. [1] (ii) Hence, draw the electrophilic substitution mechanism of the reaction. [2] (iii) The posit