RI 2025+Post+Prelim+TP+QP

© Raffles Institution 2025 9729/02/S/25 [Turn Over RAFFLES INSTITUTION 2025 YEAR 6 TIMED PRACTICE (ADAPTED FROM 2025 TJC Prelim) Higher 2 CANDIDATE NAME CLASS INDEX NUMBER CHEMISTRY 9729/02 Paper 2 Structured Questions 16 October 2025 2 hours Candidates answer on the Question Paper. Additional Materials: Data Booklet READ THESE INSTRUCTIONS FIRST Do not open this question booklet until you are told to do so. Write your name, class and index number in the spaces at the top of this page. Write in dark blue or black pen. You may use an HB 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. Do not write anything in it. You are reminded of the need for good English and clear presentation in your answers. At the end of the examination, fasten all your work securely together. The number of marks is given in brackets [ ] at the end of each question or part question. For Examiner’s Use 1 / 10 2 / 9 3 / 9 4 / 15 5 / 11 6 / 21 Total / 75 This document consists of 21 printed pages.

© Raffles Institution 2025 9729/02/O/25 [Turn Over 2 Answer all questions in the space provided. 1 (a) In 1932, the American chemist Linus Pauling developed the most common scale of relative electronegativity (EN) values for the elements. The Pauling EN values of elements can be used to predict the chemical properties of compounds. The EN values of four Per iod 3 elements are given in Table 1.1. Table 1.1 element sodium aluminium phosphorus chlorine Pauling EN value 0.93 1.61 2.19 3.16 l (i) Explain the difference in the Pauling electronegativity values of Na and Cl. ……………………………………………………………………………………..….............. ……………………………………………………………………………………..….............. ……………………………………………………………………………………..….............. ……………………………………………………………………………………..….............. ……………………………………………………………………………………..…......... [2] The ionic character of a bond is directly related to the electronegativity difference (∆EN) between the bonded atoms. Fig. 1.1 shows the plot of percent ionic character against ∆EN for NaCl. Fig. 1.1

© Raffles Institution 2025 9729/02/O/25 [Turn Over 3 (ii) Using the values in Table 1.1, calculate ∆EN for AlCl3 and PCl5 respectively. Hence plot the percent ionic character of AlCl3 and PCl5 on Fig. 1.1. Label your points clearly. [2] (iii) Explain the difference in bonding for NaCl and PCl5 in terms of electronegativity. ……………………………………………………………………………………..….............. ……………………………………………………………………………………..….............. ……………………………………………………………………………………..….............. ……………………………………………………………………………………..….............. ……………………………………………………………………………………..…......... [2] (b) (i) The polarity of bonds in covalent molecules is also affected by ∆EN. SeF4 and BrF3 are two fluorine-containing molecules. State whether SeF 4 or BrF3 contains covalent bonds with a higher ionic character. ……………………………………………………………………………………..…......... [1] (ii) Using VSEPR theory, predict and explain the shape and bond angles of SeF4. Illustrate the shape of SeF4 with an appropriate diagram. ……………………………………………………………………………………..….............. ……………………………………………………………………………………..….............. ……………………………………………………………………………………..….............. ……………………………………………………………………………………..….............. ……………………………………………………………………………………..…......... [3] [Total: 10]

© Raffles Institution 2025 9729/02/O/25 [Turn Over 4 2 PCl5 is a Period 3 chloride commonly used as a chlorinating agent and catalyst in making organic compounds. Industrial production of PCl5 involves the reaction of Cl2 with PCl3. Reaction (1) PCl3(g) + Cl2(g) ⇌ PCl5(g) (a) Suggest, with an explanation, how the position of equilibrium and the composition of the equilibrium mixture might change when chlorine is added to the equilibrium system. ……………………………………………………………………………………..………………….. ……………………………………………………………………………………..………………….. ……………………………………………………………………………………..………………….. ……………………………………………………………………………………..…………….. [2] (b) x mol of Cl2 gas is added to a 2 dm 3 vessel containing an equilibrium system of 0.4 mol of PCl3, 0.25 mol of C l2 gas and 1.2 mol of PC l5. The new equilibrium amount of PC l5 is 1.28 mol. (i) Write the Kc expression for reaction (1), giving its units. ……………………………………………………………………………………..…......... [1] (ii) Using the information given above, calculate Kc. [1] (iii) Hence calculate x, the amount of Cl2 added. [2]

© Raffles Institution 2025 9729/02/O/25 [Turn Over 5 (c) Period 3 oxides follow a similar trend in bonding as the Period 3 chlorides. Describe the action of water on the oxides of sodium, aluminium and phosphorus, write equations for any reactions that occur, and suggest the pH of each solution formed. ……………………………………………………………………………………..………………….. ……………………………………………………………………………………..………………….. ……………………………………………………………………………………..………………….. ……………………………………………………………………………………..………………….. ……………………………………………………………………………………..………………….. ……………………………………………………………………………………..………………….. ……………………………………………………………………………………..………………….. ……………………………………………………………………………………..…………….. [3] [Total: 9]

© Raffles Institution 2025 9729/02/O/25 [Turn Over 6 3 (a) Nitrogen exhibits a range of oxidation numbers in its compounds. A few of such species are NO, N2O, NO2, N2 and NH2OH. (i) Draw the dot-and-cross diagram for NO2. [1] 0.074 g of hydroxylamine, NH2OH, is dissolved in water. Excess solution of acidified iron(III) salt is added to the dissolved hydroxylamine to form a nitrogen -containing product and iron(II) ions. The iron( II) ions produced requires 44.8 cm 3 of 0.02 mol dm -3 acidified potassium manganate(VII) for complete reaction. The reacting ratio of iron(II) ions and manganate(VII) ions is 5:1. (ii) Calculate the amount of iron(III) reacted with hydroxylamine. [1] (iii) Determine the oxidation state of the nitrogen atom in the nitrogen-containing product. Hence deduce the identity of the nitrogen-containing product. [2]

© Raffles Institution 2025 9729/02/O/25 [Turn Over 7 (iv) Construct a balanced ionic equation for the reaction of NH2OH with Fe3+. [1] (b) Figure 3.1 shows the second ionisation energies of nine consecutive elements A to I with atomic numbers below 20 in the Periodic Table. Labels A to I are not the atomic symbols of the elements. Fig. 3.1 (i) Define the second ionisation energy of element F. ……………………………………………………………………………………..….............. ……………………………………………………………………………………..….............. ……………………………………………………………………………………..…......... [1] (ii) Suggest the identity of B. Explain how you arrived at your answer. ……………………………………………………………………………………..….............. ……………………………………………………………………………………..….............. ……………………………………………………………………………………..….............. ……………………………………………………………………………………..….............. ……………………………………………………………………………………..…......... [2]

© Raffles Institution 2025 9729/02/O/25 [Turn Over 8 (iii) Explain the difference in second ionisation energy between element A and element B. ……………………………………………………………………………………..….............. ……………………………………………………………………………………..….............. ……………………………………………………………………………………..…......... [1] [Total: 9]

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