2026 H2 Timed Practice Paper 2 QP (to upload)

NJC SH2 Timed Practice 9476/2/26 [Turn over NATIONAL JUNIOR COLLEGE SH2 MID YEAR TIMED PRACTICE Higher 2 CANDIDATE NAME SUBJECT CLASS REGISTRATION NUMBER CHEMISTRY Paper 2 Structured Questions Candidates answer on Question Paper. Additional Materials: Data Booklet 9476/02 7 July 2026 2 hours READ THE INSTRUCTIONS FIRST Write your subject class, registration number and name on all the work you hand in. Write in dark blue or black pen. You may use a soft pencil for any diagrams or graphs. Do not use staples, 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. For Examiner’s Use 1 /7 2 /19 3 /15 4 /18 5 /12 6 /9 Paper 2 Total /80 This document consists of 24 printed pages including 1 blank page.

2 NJC SH2 Timed Practice 9476/2/26 1 (a) Two organic compounds, A and B, can co -polymerise to produce a polyester. On treatment with hot acidified sodium dichromate( VI), compound A, C4H10O2, is converted into compound B. Compound B can also be formed from fumaric acid, HO2CCH=CHCO2H, upon treatment with hydrogen over a nickel catalyst (i) Draw the structures for compounds A and B. A B [2] (ii) Draw the structural formula of one repeat unit of the polymer formed from compounds A and B. [1] Poly(A-B) is a biodegradable plastic and can be used for food packaging like disposable tablewares and paper cups. (iii) Suggest why poly(A-B) is biodegradable. …………………………………………………………………………………….…. ……………………………………………………………………….………………. ……………………………………………………………………………………….. [1]

3 NJC SH2 Timed Practice 9476//2/26 [Turn over (b) Ethane-1,2-diol, HOCH2CH2OH, has a wide variety of uses including in antifreeze in cars. Ethane-1,2-diol undergo a series of steps to form NH2CH2CH2NH2. HOCH2CH2OH Step 1 Y ethanolic NH3 heat in sealed tube H2NCH2CH2NH2 (i) Suggest the structure of Y and state the reagents and conditions for step 1. Y: ………………………………………………………………………………. Step 1: ………………………………………………………………………………. [2] (ii) Deduce which compound, HOCH 2CH2OH or NH 2CH2CH2NH2 has a higher boiling point. …………………………………………………………………………………….…. …………………………………………………………………………………….…. ………….………………………………………………………………………... [1] [Total: 7]

4 NJC SH2 Timed Practice 9476/2/26 2 Bromine can form several compounds under suitable conditions as shown in Table 2.1. Table 2.1 Bromine containing species Oxidation number of Br Br − −1 BrO− +1 BrF4− +3 BrO3− +5 BrO4− +7 (a) (i) Draw the dot-and-cross diagram for BrO3−. [1] (ii) State and explain the bond angle in BrO3−. …………………………………………...…………………………………………… …………………………………………...…………………………………………… …………………………………………...…………………………………………… …………………………………………...…………………………………………… …………………………………………...…………………………………………… …………………………………………...…………………………………………… …………………………………………...…………………………………………… …………………………………………...…………………………………………… [2]

5 NJC SH2 Timed Practice 9476//2/26 [Turn over (b) When a sample of 9.909 g of Br2(l) was reacted with an excess of aqueous NaOH, two different bromine containing ions, X and Y, are formed. The identities of X and Y can be found in Table 2.1. The resulting mixture was then made up to 250 cm 3 with deionised water to form solution Q. The following procedures were carried out on solution Q. 1. When 25.0 cm3 of solution Q was acidified with an excess of acid, followed by the addition of AgNO3(aq), a cream precipitate was formed. 2. This precipitate was insoluble in excess NH3(aq), and its mass was found to be 1.942 g. 3. To a separate 25.0 cm3 portion of solution Q, excess KI solution was added. The I2 liberated required 24.80 cm 3 of 0.500 mol dm -3 Na2S2O3 for complete reaction as shown. 2S2O32– + I2 → S4O62– + 2 I – (i) Given that ion X is responsible for the formation of the cream precipitate, state the identity of X. Ion X: ………………………… [1] (ii) Calculate the amount of X in 25.0 cm3 of solution Q. [1] (iii) Calculate the amount of bromine atoms in 9.909 g of Br2(l). Hence, show that there are 0.00206 mol of Y in 25.0 cm3 of solution Q. [2]

6 NJC SH2 Timed Practice 9476/2/26 (iv) In step 3, Y reacts with KI to form X. Deduce the oxidation state of Br in Y. [2] (v) Using Table 2.1 and your answers in (iii) and (iv), construct the balanced equation for reaction between Br2 and NaOH. ………………………………………………………………………………..……[1]

7 NJC SH2 Timed Practice 9476//2/26 [Turn over (c) Br− reacts with BrO3− in acidified medium as shown. BrO3− + Br − + 6H+ → 3Br2 + 3H2O A series of kinetic experiments were conducted on this reaction and the data collected were tabulated in Table 2.2. Table 2.2 Expt [BrO3−] / mol dm−3 [Br−] / mol dm−3 [H+] / mol dm−3 Initial rate / mol dm−3 s−1 1 1.20 0.100 1.50 1.00 × 10−2 2 2.40 0.100 1.50 2.00 × 10−2 3 1.80 0.200 1.50 3.00 × 10−2 (i) Use Table 2.2, deduce the order of reaction with respect to [BrO3−] and [Br −]. [2] (ii) Given that the reaction is 2nd order with respect to [H+], calculate the value of rate constant, k, for experiment 1. Include its units. [1]

8 NJC SH2 Timed Practice 9476/2/26 (iii) The initial rate of experiment 1 is determined from the gradient of tangent at time, t = 0 when concentration of Br− is monitored with time. Given that the concentrations of BrO3− and H+ remain unchanged during the course of reaction, calculate the half-life of this reaction. Hence sketch the graph of [Br−] against time. [2]

9 NJC SH2 Timed Practice 9476//2/26 [Turn over (d) A bromine compound, BrCl reacts with benzene, in the presence of A lCl3, to form a monohalogenobenzene, C6H5X. (i) Suggest whether the product C 6H5X is chlorobenzene or bromobenzene. Explain your answer. …………………………………………………………………………..…………… …………………………………………………………………………..…………… ……………………………………………………………………………………. [1] (ii) Draw the mechanism of the reaction. Include all the relevant dipoles, curly arrows and charges. Include the structure of the organic intermediate. [3] [Total: 19]

10 NJC SH2 Timed Practice 9476/2/26 3 (a) Chloroform, CHCl₃ is commonly used as a solvent for paints, lacquers, adhesives, and floor polishes. It can undergo hydrolysis in basic conditions as follows. CHCl₃(aq) + 4O