HCI 2026 Prelim P2 QP

This document has 18 pages. Any blank pages are indicated. HWA CHONG INSTITUTION C2 Preliminary Examination Higher 2 CANDIDATE NAME CT GROUP 2 5 S CENTRE NUMBER S INDEX NUMBER CHEMISTRY Paper 2 Structured Questions 9476/02 2 September 2026 2 hours You must answer on the question paper. You will need: Data Booklet READ THESE INSTRUCTIONS FIRST • Write your name, CT group, centre number and index number in the boxes at the top of the page. • Write and shade your Student ID using a 2B pencil. Your Student ID is xxxxxxx, where your HCI email is xxxxxxx@student.hci.edu.sg • Answer all questions. • Use a black or dark blue pen. You may use a HB pencil for any diagrams or graphs. • Write your answer to each question in the space provided. If additional space is required, you should use the blank pages in this booklet. The question number must be clearly shown. • Do not use an erasable pen. Do not use correction fluid or tape. Do not write on any bar codes. • Do not remove any staple; Do not detach any pages of this question booklet. • You may use an approved calculator. INFORMATION • The total mark for this paper is 75. • The number of marks for each question or part question is shown in brackets [ ]. For Examiner’s Use 1 / 7 2 / 14 3 / 16 4 / 13 5 / 25 Deductions (s.f.) Deductions (units) Deductions (structures) Total / 75

2 © Hwa Chong Institution 2026 9476/02/C2 Preliminary Examination DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN [Turn Over Answer all questions in the spaces provided. 1 (a) (i) State the number of protons, neutrons and electrons in a 18O+ ion. number of protons: ………… number of neutrons: ………… number of electrons: ………… [1] (ii) The relative abundances of all the isotopes present in a sample of oxygen are shown in Table 1.1. Table 1.1 isotope mass of isotope relative abundance oxygen-16 16 97.10 oxygen-17 17 1.53 oxygen-18 18 0.47 Calculate the relative atomic mass of oxygen in this sample. Give your answer to two decimal places. [2]

3 © Hwa Chong Institution 2026 9476/02/C2 Preliminary Examination DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN [Turn Over (b) (i) Explain why the first ionisation energies of the elements Sc to Cu are relatively constant. ……………………………………………………….……………………………………………… ……………………………………………………….……………………………………………… ……………………………………………………….……………………………………………… ……………………………………………………….……………………………………………… ……………………………………………………….……………………………………………… …………………………………………………………………………………………….………[2] (ii) Table 1.2 shows the first and second ionisation energies for some elements. Table 1.2 element first ionisation energy / kJ mol−1 second ionisation energy / kJ mol−1 vanadium 648 1370 chromium 653 1590 manganese 716 1510 With the aid of relevant electronic configurations for chromium, explain why the energy increase between the first and second ionisation energies for chromium is larger than that for vanadium and manganese. ……………………………………………………….……………………………………………… ……………………………………………………….……………………………………………… ……………………………………………………….……………………………………………… …………………………………………………………………………………………….………[2] [Total: 7]

4 © Hwa Chong Institution 2026 9476/02/C2 Preliminary Examination DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN [Turn Over 2 (a) [Co(H2O)6]2+ and [Co(NH3)6]2+ are two examples of Co(II) complexes. An aqueous solution of [Co(H2O)6]2+ is pink, while an aqueous solution of [Co(NH3)6]2+ is yellow. Explain the origin of colour in Co(II) complexes, and why the two complexes are different in colour. ..……………………………..……………….……………………………………………………...…...… ..……………………………..……………….……………………………………………………...…...… ..……………………………..……………….……………………………………………………...…...… ..……………………………..……………….……………………………………………………...…...… ..……………………………..……………….……………………………………………………...…...… ..……………………………..……………….……………………………………………………...…...… ..……………………………..……………….……………………………………………………...…...… ..……………………………..……………….……………………………………………………...…...… ..……………………………..……………….……………………………………………………...…...… ..……………………………..……………….……………………………………………………...…...… ..……………………………..……………….……………………………………………………...…...… ..……………………………..……………….……………………………………………………...…...… ..……………………………..……………….……………………………………………………...…...… ..……………………………..……………….……………………………………………………...…...… ..……………………………..……………….……………………………………………………...….. [4]

5 © Hwa Chong Institution 2026 9476/02/C2 Preliminary Examination DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN [Turn Over (b) Figure 2.1 shows a reaction scheme for the preparation of [Co(en)2Cl2]Cl, a green crystalline solid. The compound ethane-1,2-diamine, H2N(CH2)2NH2, abbreviated as en, is a bidentate ligand. ① ② ③ [Co(H2O)6]2+ → [Co(en)2Cl2] → [Co(en)2Cl2](OH) → [Co(en)2Cl2]Cl Figure 2.1 (i) Deduce the type of reaction undergone by [Co(en)2Cl2] in step ②. Explain your answer clearly. ……………………………………………………….……………………………………………… ……………………………………………………….……………………………………………… ……………………………………………………….……………………………………………… …………………………………………………………………………………………….………[1] (ii) Co3+(aq) is very unstable in water because a redox reaction occurs readily. Construct a balanced equation for the redox reaction between Co3+(aq) and water. Using relevant Eo values from the Data Booklet, calculate Go for this reaction. [2] (iii) Based on the information given in (b), suggest why the incorporation of en ligands in step ① might be necessary in the preparation of [Co(en)2Cl2]Cl. ……………………………………………………….……………………………………………… ……………………………………………………….……………………………………………… …………………………………………………………………………………………….………[1] (c) H2N(CH2)2NH2 can be prepared from ethene in two steps. State the reagents and conditions required for each step. step 1: …………………………………………………………………………………………………….. step 2: …………………………………………………………………………………………………….. [2]

6 © Hwa Chong Institution 2026 9476/02/C2 Preliminary Examination DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN [Turn Over (d) Like organic molecules, transition metal complexes can exhibit stereoisomerism. Figure 2.2 shows the three-dimensional structures of three stereoisomers of [Co(en)2Cl2]. A B C Figure 2.2 Deduce whether an equimolar mixture of A, B and C rotates plane-polarised light. Explain your reasoning. ..……………………………..……………….……………………………………………………...…...… ..……………………………..……………….……………………………………………………...…...… ..……………………………..……………….……………………………………………………...…...… ..……………………………..……………….……………………………………………………...…...… ..……………………………..……………….……………………………………………………...….. [2] (e) The ethylenediaminetetraacetate ion, EDTA4–, is a ligand that forms six dative bonds with a metal ion. When aqueous EDTA4– is added to [Co(H2O)6]2+, a ligand exchange reaction occurs to form an octahedral complex with a coordination number of six. Write a balanced equation for this reaction and suggest, with reasoning, the sign of S for this reaction. ..……………………………..……………….…