CJC 2026 H2 Prelim 9476 P4 Solution

[Turn over 9476/04/CJC JC2 Preliminary Examinations 2026 CANDIDATE NAME CLASS 2T CHEMISTRY 9476/04 Paper 4 Practical 25 August 2026 2 hours 30 minutes You must answer on the question paper. You will need: The materials and apparatus listed in the confidential instructions INSTRUCTIONS • Answer all questions. • Use a black or dark blue pen. You may use an HB pencil for any diagrams or graphs. • Write your name and class in the boxes at the top of the page. • Write your answer to each question in the space provided. • Do not use an erasable pen. Do not use correction fluid or tape. • You may use an approved calculator. • Qualitative analysis notes are printed in the question paper. • Write the details of the shift and laboratory in the boxes provided. INFORMATION • The total mark for this paper is 50. • The number of marks for each question paper or part question is shown in brackets [ ]. This document consists of 18 printed pages. Instruction Catholic Junior College JC2 Preliminary Examinations Higher 2 Shift Laboratory For Examiner’s Use 1 / 14 2 / 11 3 / 8 4 / 17 Total / 50

2 9476/04/CJC JC2 Preliminary Examinations 2026 Answer all the questions in the spaces provided. 1 Identification of two cations and one anion FA 1 is an aqueous solution containing two cations and one anion listed in the Qualitative Analysis notes on pages 16 and 17. You will perform tests to identify the two cations and one anion in FA 1. Unless otherwise stated, the volumes given below are approximate and should be estimated rather than measured. Colours of filtrates and residues should be reported. You do not need to test any gases evolved. If there is no observable change, write no observable change. (a) (i) Carry out the following tests. Carefully record your observations at each stage of the tests in Table 1.1. Table 1.1 tests observations 1 Test the FA 1 solution using Universal Indicator paper. Hence, conclude the pH of FA 1 solution. 2 Add 1 cm depth of FA 1 into a clean test-tube. Add 3 cm depth of aqueous sodium hydroxide, slowly with shaking, to FA 1. Filter the mixture into a clean boiling tube. Keep the filtrate for test 4. While waiting, proceed to test 3. 3 Add 1 cm depth of FA 1 into a clean test-tube. Add aqueous ammonia, slowly with shaking, until no further change is seen. Note: colour of ppt in excess cannot be observed well. 4 To the filtrate from test 2, carefully add dilute sulfuric acid dropwise until no further change is seen. Note: The appearance & dissolution of the ppt does not happen within mere drops, so students should not miss it. • Universal indicator paper turns red / orange pH 1(red) – 3(orange) [1] • (Pale) blue ppt insoluble in excess [1] • Blue/blue-green residue and colourless filtrate [1] • (Pale) blue ppt in colourless solution (partially) soluble in excess to give a ppt in dark blue solution [1] – Cu2+ observation (blue ppt dissolve to form dark blue solution [1] – (Al3+) ppt remaining in solution • White ppt soluble in excess to give a colourless solution [1]

3 [Turn over 9476/04/CJC JC2 Preliminary Examinations 2026 5 Add 1 cm depth of FA 1 into a clean test-tube. Add an equal volume of potassium iodide, KI(aq), and shake. To this mixture, add 15 drops of sodium thiosulfate, Na2S2O3(aq), and shake. [8] (ii) Identify the two cations present in FA 1. Cations present: …………. and …………. [2] (b) (i) FA 1 does not contain CO32‒, NO2‒, NO3‒ and SO32‒. Devise and perform two tests to identify the anion present in FA 1. Your tests should be based on the Qualitative Analysis Notes provided on page 17 and should use only the bench reagents provided. Record your tests and observations in the space below. tests observations 1 Add 1 cm depth of FA 1 into a clean test-tube. Add a few drops of aqueous silver nitrate, with shaking, to FA 1. If a precipitate forms, add 1 cm depth of aqueous ammonia to the mixture and shake. 2 Add 1 cm depth of FA 1 into a clean test-tube. Add a few drops of aqueous barium nitrate, with shaking, to FA 1. [2] (ii) Use your observations in (b)(i) to deduce the identity of the anion in FA 1. Identity of anion: ……….. [1] • Blue solution turns green, then yellow, then • (White/brown) ppt in brown solution • Brown solution is decolourized / turns colourless leaving behind a white ppt [1] – ppt seen with KI and revealed to be white with S2O32- [1] – brown solution seen with KI and decolourised with S2O32- Al3+[1] Cu2+ [1] • No observable change [1 for test and correct observation] • White ppt [1 for test and correct observation (ignore mention of aqueous acid)] SO42– [1]

4 9476/04/CJC JC2 Preliminary Examinations 2026 (c) A student discovered a bottle of solution with the label “ammonium nitrate, NH4NO3(aq)” and decided to conduct some tests to verify whether the solution was indeed as labelled. Subsequently, the student correctly identified the presence of NH 4+ in the solution through the addition of aqueous sodium hydroxide followed by heating. Suggest why the student might find it difficult to identify the presence of NO 3‒ in the solution. ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………….……………..[1] [Total: 14] Note: There is a way to get around this limitation. Add NaOH(aq) and heat until all NH3 has been liberated (use fresh strips of damp red litmus paper and keep on testing until the litmus paper remains red). Then, add Al foil and continue heating. If NH3 is produced, turning damp red litmus paper blue, this NH3 should have been produced from NO3‒. The test for NO3‒ also requires NaOH(aq) and heating, as well an additional reagent of Al foil. Hence, it would not be possible to tell if NH3 was produced from NH4+ or NO3‒. [1, owtte]

5 [Turn over 9476/04/CJC JC2 Preliminary Examinations 2026 2 Organic analysis In this question, you will deduce the identities of the organic compounds FA 2, FA 3, FA 4 and FA 5. • Each compound contains only carbon, hydrogen and oxygen. • Each molecule contains only three carbon atoms and only one oxygen atom. You will perform a series of test -tube reactions and use the observations to help you identify the compounds. The observations for some of the reactions , including all observations for FA 5, have already been recorded in Table 2.1. You are provided with: • liquid samples FA 2, FA 3 and FA 4 • iodine solution • other necessary bench reagents. (a) Follow the instructions below to prepare Tollens’ reagent. To a 2 cm depth of aqueous silver nitrate in a test -tube, add 4 drops of aqueous sodium hydroxide. Then add aqueous ammonia dropwise, with shaking, until the brown solid just dissolved. Do not add an excess of aqueous ammonia. Perform the tests described in Table 2.1 on page 6, and record your observations in the table. If there is no observable change, write no observable change. Use a fresh sample of each liquid in each test. (i) Carry out the following tests. Carefully record your observations in Table 2.1. The volumes given below are approximate and should be estimated rather than measured. You do not need to test for any gases evolved.

6 [Turn over 9476/04/CJC JC2 Preliminary Examinations 2026 Table 2.1 tests observations with FA 2 observations with FA 3 observations with FA 4 observations with FA 5 1 Add 1 cm depth of Tollens’ reagent to a clean test-tube. Add 5 drops of FA 3 and shake the test-tube. Place