2023 RI H2 Chem Prelims P3 Questions

RAFFLES INSTITUTION 2023 YEAR 6 PRELIMINARY EXAMINATION Higher 2 CANDIDATE NAME CLASS INDEX NUMBER CHEMISTRY 9729/03 Paper 3 Free Response 20 September 2023 2 hours Candidates answer on the Question Paper. Additional Materials: Data Booklet READ THESE INSTRUCTIONS FIRST Do not open this question booklet until you are told to do so. Write your name, class and index number 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. The use of an approved scientific calculator is expected, where appropriate. A Data Booklet is provided. Do not write anything in it. You are reminded of the need for good English and clear presentation in your answers. 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 Total 1 / 20 (Circle the question you have answered) / 80 2 / 20 4 / 20 3 / 20 5 / 20 This document consists of 27 printed pages and 1 blank page.

2 © Raffles Institution 2023 9729/03/S/23 [Turn Over Section A Answer all the questions in this section. 1 (a) Elemental silicon does not occur naturally and is obtained from SiO2 in rocks. (i) Silicon has a similar structure to diamond. However, the melting point of silicon at 1414 C is lower than that of diamond at 3550 C. Explain this difference with reference to the structure and bonding of silicon and diamond. [2] (ii) Describe the difference in the acid-base behaviour of A l2O3 and SiO 2. Write relevant equations to illustrate your answer. [3] ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ………………………………………………………………………………………………

3 © Raffles Institution 2023 9729/03/S/23 [Turn Over (b) The standard enthalpy change of formation, Hf,