2024 Prelims ACJC H2 Chem P3 (QP)

This document consists of 30 printed pages and 2 blank pages. Anglo-Chinese Junior College JC2 Preliminary Examination Higher 2 CANDIDATE NAME FORM CLASS 2 TUTORIAL CLASS 2CH INDEX NUMBER CHEMISTRY Paper 3 Free Response Candidates answer on the Question Paper. Additional Materials: Data Booklet 9729/03 27 August 2024 2 hours READ THESE INSTRUCTIONS FIRST Write your index number and name 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. Circle the number of the question you have attempted. 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 Examiners’ use only Section A 1 / 20 2 / 20 3 / 20 Section B 4 / 5 / 20 Presentation Total / 80

2 © ACJC2024 9729/Preliminary Examination/2024 [Turn over Section A Answer all the questions in this section. 1 (a) Describe the variation in the behaviour of Period 3 chlorides NaCl, AlCl3 and PCl5 separately with water. Write equations for any reactions described and state the pH of the resultant solutions. [3] ………………………………………………………………………………………………………… ………………………………………………………………………………………………….…….. ………………………………………………………………………………………………….…….. ………………………………………………………………………………………………….…….. ……………………………………………………………………………………………….……….. ………………………………………………………………………………………………….…….. ………………………………………………………………………………………………….…….. ………………………………………………………………………………………………….…….. ………………………………………………………………………………………………….…….. ………………………………………………………………………………………………….…….. (b) When soil becomes acidic, aluminium leeches out of minerals into the soil. High aluminium content in soil affects root growth and causes the roots to be brittle. These problems are minimised if the topsoil pH is maintained above 5.5. In a study of a soil condition, a sample of soil water was titrated with EDTA4−, a hexadentate ligand, to determine its aluminium ion concentration. equation 1 [Al(H2O)6]3+(aq) + EDTA4−(aq) [Al(EDTA)]−(aq) + 6H2O(l) (i) State the type of reaction in equation 1. [1] (ii) The concentration of aluminium ions in the soil water sample was found to be 2.90 × 10–5 mol dm–3. Calculate th