HCI 2026 Prelim P3 QP

This document has 22 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 3 Structured Questions 9476/03 16 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 • Section A: answer all questions. • Section B: answer one question. • 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. • 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 / 21 2 / 14 3 / 20 Circle your option below 4 / 5 / 20 Deductions (s.f.) Deductions (units) Deductions (structures) Total / 75

2 © Hwa Chong Institution 2026 9476/03/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 Section A Answer all the questions in this section in the spaces provided. 1 (a) Copper minerals often contain copper sulfide mixed with the sulfides of silver and nickel. Solid impure copper is purified by electrolysis. Draw a diagram to show the electrolysis set up for the purification of impure copper. With the aid of the Data Booklet, describe the electrode reactions that take place during this electrolysis, and explain in detail how silver and nickel are removed from impure copper. ..……………………………..……………….……………………………………………………...…...… ..……………………………..……………….……………………………………………………...…...… ..……………………………..……………….……………………………………………………...…...… ..……………………………..……………….……………………………………………………...…...… ..……………………………..……………….……………………………………………………...…...… ..……………………………..……………….……………………………………………………...…...… ..……………………………..……………….……………………………………………………...…...… ..……………………………..……………….……………………………………………………...…...… ..……………………………..……………….……………………………………………………...…...… ..……………………………..……………….……………………………………………………...…...… ..……………………………..……………….……………………………………………………...…...… ..……………………………..……………….……………………………………………………...…...… ..……………………………..……………….……………………………………………………...…...… ..……………………………..……………….……………………………………………………...….. [5]

3 © Hwa Chong Institution 2026 9476/03/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) Copper(II) hydroxide, Cu(OH)2, and iron(III) hydroxide, Fe(OH)3, are sparingly soluble in water. Table 1.1 lists the value of the solubility product, Ksp, for each hydroxide, at 298 K. Table 1.1 compound Ksp Cu(OH)2 1.60 × 10 –19 Fe(OH)3 2.70 × 10 –39 An aqueous solution contains 0.100 mol dm–3 of Cu2+(aq) and 0.100 mol dm–3 of Fe3+(aq). To separate both the cations, solid NaOH is added into the solution. (i) Calculate • the minimum concentration of OH– needed to just precipitate Cu2+ as Cu(OH)2, and • the minimum concentration of OH– needed to just precipitate Fe3+ as Fe(OH)3. Hence, determine which metal cation will precipitate first. [2] (ii) Cation separation via selective precipitation is considered complete when at least 99.9% of the first cation has precipitated, leaving 0.1% or less of that ion remaining in the solution. With the aid of suitable calculations, determine if the separation of Cu2+ and Fe3+ is considered complete, at the point when the second cation just starts to precipitate. [2]

4 © Hwa Chong Institution 2026 9476/03/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 (c) Organocuprates belong to a class of compounds that have the general formula, R2CuLi, where R represents any alkyl or aryl group. Organocuprates react with epoxides, which are three- membered rings containing one oxygen atom, to form alcohols. An example is shown in Figure 1.1. Figure 1.1 (i) Write the systematic name for alcohol A. …………………………………………………………………………………………….……… [1] (ii) A second alcohol B could theoretically be formed in the same reaction. Describe a simple chemical test to distinguish between alcohols A and B. State what you would observe for each alcohol. ……………………………………………………….……………………………………………… ……………………………………………………….……………………………………………… …………………………………………………………………………………………….……… [2] (iii) The reaction in Figure 1.1 undergoes an SN2-like mechanism, where the organocuprate provides the CH3CH2– nucleophile that attacks the electron deficient carbon. After performing the distinguishing test, only alcohol A is formed through the reaction. Explain why only alcohol A is formed. ……………………………………………………….……………………………………………… ……………………………………………………….……………………………………………… …………………………………………………………………………………………….……… [1]

5 © Hwa Chong Institution 2026 9476/03/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) An organocuprate C reacts with epoxide D to form alcohol E, C9H12O. When E undergoes oxidation, F is formed. A series of tests are carried out on F. The tests and the results are recorded in Table 1.2 Table 1.2 test on F observations / results type of reaction functional group identified in F addition of 2,4- DNPH orange precipitate formed addition of Tollens’ reagent no silver mirror formed addition of alkaline aqueous iodine yellow precipitate formed (i) Complete Table 1.2 to give the type of reaction described and what the information tells you about the functional groups present in F. [2] (ii) E reacts with hot acidified KMnO4 to form G, C7H6O2. Taking into account your answer in (d)(i), as well as the information provided in Figure 1.1 and (c)(iii), deduce the structures of unknowns C to G. Explain your reasoning. You may find it useful to determine the structures of E, F and G first. ……………………………………………………….……………………………………………… ……………………………………………………….……………………………………………… …………………………………………………………………………………………….………[6] [Total: 21]

6 © Hwa Chong Institution 2026 9476/03/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 Cholamine halide is a weak base. cholamine halide, C5H15N2X (X is a Group 17 element) (a) Despite the presence of two nitrogen atoms, cholamine halide has only one Kb value. Identify which of the two nitrogen-containing functional groups does not have an associated Kb value and explain your answer. ..……………………………..……………….……………………………………………………...…...… ..……………………………..……………….