2025 JC2 Prelims H2 Chem Paper 3 QP_TJC

9729 / TJC Prelims / 2025 DO NOT WRITE IN THIS MARGIN [Turn over TEMASEK JUNIOR COLLEGE 2025 JC2 PRELIMINARY EXAMINATION Higher 2 CANDIDATE NAME CENTRE NUMBER S INDEX NUMBER Chemistry 9729/03 Paper 3 Free Response Questions 15 September 2025 2 hours Candidates answer on the Question Paper. Additional Materials: Data Booklet READ THESE INSTRUCTIONS FIRST Write your name, civics class, centre number 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. 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 This document consists of 27 printed pages and 1 blank page. For Examiner’s Use Paper 3 Q1 Q2 Q3 Q4 Q5 Total /80

2 DO NOT WRITE IN THIS MARGIN 9729 / TJC Prelims / 2025 DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN Section A Answer all the questions in this section. 1 Schweizer's reagent is used in purifying cellulose . This dark blue compound has the formula, [Cu(NH3)4(H2O)2](OH)2 and contains the tetraamminediaquacopper(II) cation, [Cu(NH3)4(H2O)2]2+. (a) Explain the origin of the dark blue colour of the tetraamminediaquacopper(II) cation. [3] ................................ ................................ ................................ ................................ ............. ................................ ................................ ................................ ................................ ............. ................................ ................................ ................................ ................................ ............. ................................ ................................ ................................ ................................ ............. ................................ ................................ ................................ ................................ ............. ................................ ................................ ................................ ................................ ............. ................................ ................................ ................................ ................................ .......