NJC 2026 H2 Chemistry Prelim P4 QP

1 NJC SH2 Preliminary Examination 9476/04/26 NATIONAL JUNIOR COLLEGE SH 2 Prelim Practical Examination Higher 2 CANDIDATE NAME SUBJECT CLASS REGISTRATION NUMBER CHEMISTRY Paper 4 Practical You must answer on the question paper. 9476/04 Monday 31 August 2026 2 hours 30 minutes INSTRUCTIONS • Answer all questions. • Use a black or dark blue pen. You may use an HB pencil for any diagrams or graphs. • Write your identification number and name. • 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 or part question is shown in brackets [ ]. This paper consists of 20 pages. Any blank pages are indicated. Shift Laboratory For Examiner’s use 1 / 7 2 / 8 3 / 10 4 / 17 5 / 8 Total / 50

2 NJC SH2 Preliminary Examination 9476/04/26 1 Inorganic Qualitative Analysis FA 1 is a solution which contains two cations and two anions. Perform the tests described in Table 1.1 and record your observations in the table. Test and identify any gases evolved. For Examiner’s Use Table 1.1 tests observations (a) (i) To a 2 cm depth of FA 1 solution in a boiling tube , add aqueous sodium hydroxide, slowly with shaking, until 4 cm depth of aqueous sodium hydroxide is added. Gently warm the mixture. Then filter the mixture, collecting the filtrate in a clean test-tube. Leave to stand for several minutes. Keep the filtrate for test (ii) and (iii). (ii) To a 1 cm depth of the filtrate from test (i) in a test -tube, add aqueous barium nitrate dropwise. Then add dilute hydrochloric acid until there is no further change. (iii) To a 1 cm depth of the filtrate from test (i) in a test-tube, add 1 cm depth of aqueous silver nitrate. Add aqueous ammonia to the mixture, with shaking until the there is no further change. [5] (b) By considering the observations made in Table 1.1 and making reference to the Qualitative Analysis Notes, identify the cations and the anions present in FA 1. The cations in FA 1 are ______ and ______. The anions in FA 1 are ______ and ______. [2] [Total: 7]

3 NJC SH2 Preliminary Examination 9476/04/26 [Turn over 2 Organic Qualitative Analysis In this question, you will deduce the structure of an organic compound, FA 2 . The molecular formula of FA 2 is C5H10O2. Perform the tests described in Table 2.1, and record your observations in the table. Test and identify any gases evolved. Some observations have been recorded. Do not use Bunsen burner for heating. Use the hot water provided. Table 2.1 tests observations (a) (i) Place about 2 cm depth of aqueous sulfuric acid in a test-tube. To this test -tube, add 10 drops of FA 2, followed by 1 drop of aqueous potassium manganate(VII). Warm the mixture in the hot water bath for two minutes. (ii) Place about 2 cm depth of aqueous silver nitrate in a test-tube. To this test -tube, add 10 drops of aqueous sodium hydroxide, followed by aqueous ammonia until a clear solution is formed. To this test -tube, add 10 drops of FA 2. Warm the mixture in the water bath for two minutes. (iii) Place about 1 cm depth of deionised water in a test-tube. To this test-tube, add 10 drops of FA 2 and add 10 drops of aqueous sodium hydroxide. Now add iodine solution dropwise, until a permanent yellow/orange colour is obtained. Warm the mixture in the water bath for two minutes. [3]

4 NJC SH2 Preliminary Examination 9476/04/26 (b) (i) When sodium metal and 2,4 -dinitrophenylhydrazine are added to separate samples of FA 2 , effervescence extinguishes a lighted splint with a “pop” sound and an orange precipitate is observed respectively. Use this information and the observations recorded in table 2.1, identify two functional groups present in FA 2. Give evidence(s) to support your conclusion. Functional group: _____________ Evidence: [2] Functional group: _____________ Evidence: [2] (ii) Suggest a structure of FA 2 given that it contains a chiral centre. [1] [Total: 8]

5 NJC SH2 Preliminary Examination 9476/04/26 [Turn over 3 Determination of the volume strength of hydrogen peroxide The concentrations of solutions of hydrogen peroxide are often represented in terms of ‘volume strength’. In this experiment you will determine the ‘volume strength’ of a solution of hydrogen peroxide by titration with acidified potassium manganate(VII). 2MnO4–(aq) + 5H2O2(aq) + 6H+(aq) → 2Mn2+(aq) + 8H2O(l) + 5O2(g) FA 3 is 0.0300 mol dm–3 potassium manganate(VII), KMnO4. FA 4 is aqueous hydrogen peroxide, H2O2. FA 5 is 1.0 mol dm–3 sulfuric acid, H2SO4. (a) (i) Dilution of FA 4 • Pipette 25.0 cm3 of FA 4 into the 250 cm3 volumetric flask. • Make the solution up to the mark using deionised water. • Label this solution of hydrogen peroxide FA 6. This is a solution of hydrogen peroxide suitable for titration. Keep FA 5 and FA 6 for use in Question 4. Titration of FA 6 against FA 3 1. Fill the burette with FA 3. 2. Pipette 25.0 cm3 of FA 6 into a conical flask. 3. Use the 50 cm3 measuring cylinder to add 20.0 cm3 of FA 5 into the same conical flask. 4. Run FA 3 from the burette into the flask. The end -point is reached when the first permanent pink is observed. 5. Record your titration results, to an appropriate level of precision, in the space provided below. 6. Discard the reaction mixture. 7. Repeat steps 2 to 6 until consistent results are obtained. Titration results [4]

6 NJC SH2 Preliminary Examination 9476/04/26 (ii) From your titrations, obtain a suitable volume of FA 3 to be used in your calculations. Show clearly how you obtained this value. Volume of FA 3 = .............................. [1] (b) (i) Calculate the concentration of H2O2 in FA 6. Concentration of H2O2 in FA 6 = .............................. [3] (ii) Calculate the concentration of H2O2 in FA 4, in mol dm–3. concentration of H2O2 in FA 4 = .............................. mol dm–3 [1] (iii) When hydrogen peroxide decomposes in the presence of a catalyst, oxygen is produced. H2O2(aq) → H2O(l) + ½ O2(g) Calculate the volume, in dm 3, of oxygen produced when 1.00 dm 3 of FA 4 decomposes. This is the ‘volume strength’, in vol, of FA 4. (Under room conditions, 1.00 mol of gas occupies a volume of 24.0 dm3.) ‘volume strength’ of FA 4 = .............................. vol [1] [Total: 10]

7 NJC SH2 Preliminary Examination 9476/04/26 [Turn over 4 Investigating the kinetics of the reaction between hydrogen peroxide and iodide ions FA 5 is 1.0 mol dm–3 sulfuric acid, H2SO4. FA 6 is dilute aqueous hydrogen peroxide, H2O2, prepared in Question 3. FA 7 is 0.50 mol dm–3 potassium iodide, KI. FA 8 is 0.025 mol dm–3 so