2024 TMJC H2 Chem Prelim P2 (QP)

CANDIDATE NAME CIVICS GROUP H2 CHEMISTRY 9729/02 Paper 2 Structured Questions 12 September 2024 2 hours Candidates answer on the Question Paper. Additional materials: Data Booklet This document consists of 22 printed pages. READ THESE INSTRUCTIONS FIRST Write your name and civics group in the spaces at the top of this page. Write in dark blue or black pen. You may use an HB pencil for any diagrams and graphs. Do not use paper clips, glue or correction fluid. Answer all questions in the spaces provided on the Question Paper. The use of an approved scientific calculator is expected, where appropriate. A Data Booklet is provided. The number of marks is given in brackets [ ] at the end of each question or part question. TAMPINES MERIDIAN JUNIOR COLLEGE JC2 PRELIMINARY EXAMINATION For Examiner’s Use Percentage Paper 1 / 30 / 15 Paper 2 1 / 13 2 / 13 3 / 17 4 / 16 5 / 16 Paper 2 Total / 75 / 30 Paper 3 / 80 / 35 Paper 4 / 55 / 20 Grand Total / 100

2 Tampines Meridian Junior College 2024 JC2 Preliminary Examination H2 Chemistry 1 Some main group elements are similar to transition elements as they are capable of showing different oxidation states. (a) Fig. 1.1 shows a sketch of the nine successive ionisation energies of element A, a main group element. Fig. 1.1 (i) Write the equation for the third ionisation energy of element A. [1] (ii) Explain the general trend in successive ionisation energy shown in the graph of Fig. 1.1. [2] (iii) Suggest, with reasoning, the group number of element A and state its identity, given that it belongs to Period 4. [2] 1 2 3 4 5 6 7 8 9 log (IE) number of electrons removed

3 Tampines Meridian Junior College 2024 JC2 Preliminary Examination H2 Chemistry [Turn Over Transition elements form complexes that are responsible for the colour of many gemstones such sapphires and rubies. (b) Define the term transition element. [1] (c) In an isolated gas phase transition metal ion, the d-orbitals have the same energy. However, in the octahedral complex ion, [Cr(H2O)6]3+, the d subshell is spilt into two energy levels. (i) Complete the electronic configuration of Cr and Cr3+. Cr : 1s2 Cr3+ : 1s2 [1] (ii) Explain why the splitting of d-orbitals occurs in the presence of ligands. [1] (iii) Draw and name the shape of one of the d orbitals in the lower energy level and one of the d orbitals in the upper energy level for the octahedral complex ion. Indicate the axes labels clearly. Name of lower energy d orbital: __________________ Name of upper energy d orbital: __________________ [2]

4 Tampines Meridian Junior College 2024 JC2 Preliminary Examination H2 Chemistry (iv) Cr3+ ions forms a complex that gives rise to the red colour of rubies. Explain how the colour arises.