RI 2022 Y6 CT QP

1 This document consists of 41 printed pages. RAFFLES INSTITUTION 2022 YEAR 6 TERM 3 COMMON TEST Higher 2 CANDIDATE NAME CLASS INDEX NUMBER CHEMISTRY 9729 28 June 2022 2 hours 45 minutes Additional Materials: Multiple Choice Answer (OMR) Sheet Data Booklet READ THESE INSTRUCTIONS FIRST Write your name, 6-digit exam index number and civics tutorial group in the spaces provided on the OMR sheet and the cover sheets on pages 1 and 25. Shade your 6-digit exam index number on the OMR sheet. This paper consists of three sections, A, B and C. Section A (15 marks) consists of 15 multiple-choice questions. Answer this section first. The OMR sheet will be collected after the first 30 minutes. For each question there are four possible answers A, B, C and D. Choose the one you consider correct and record your choice in soft pencil on the OMR sheet. Each correct answer will score one mark. A mark will not be deducted for a wrong answer. Any rough working should be done in the question paper. Section B (40 marks) consists of 3 structured questions. Answer all questions in the spaces provided in the question paper. If additional space is required, you should use the pages at the end of the booklet for Section B (pages 23 – 24). The question number must be clearly shown. Section C (40 marks) consists of 4 free-response questions. Answer both C1 and C2, and only one of C3 EITHER or C3 OR. Answers to this section are to be written in the spaces provided in the question paper. If additional space is required, you should use the pages at the end of the booklet for Section C (pages 40 – 41). The question number must be clearly shown. Write in dark blue or black pen. You may use a n HB pencil for any diagrams or graphs. Do not use staples, paper clips, glue or correction fluid. The use of an approved scientific calculator is expected, where appropriate. The number of marks is given in brackets [ ] at the end of each question or part question. Question Marks B1 / 10 B2 / 15 B3 / 15

2 © Raffles Institution 2022 9729/J/22 [Turn Over Section A (15 marks) For each question, there are four possible answers, A, B, C, and D. Choose the one you consider to be correct. 1 Iodate(V) ions react with iodide ions under acidic conditions. IO3– + 5I– + 6H+ → 3I2 + 3H2O 25.0 cm3 of 0.100 mol dm −3 solution of iodate( V) ions was added to a solution containing excess iodide ions and sulfuric acid . The liberated iodine was then titrated with sodium thiosulfate solution. If 20.00 cm 3 of sodium thiosulfate solution was required to react with the iodine produced, what was the concentration of the sodium thiosulfate solution in mol dm−3? A 0.125 B 0.250 C 0.375 D 0.750 2 The reactivity of Group 2 metals with oxygen increases down the group. Which statement best explains the trend? A The ionic radius of the metal cations increases down the group. B The reducing power of the elements increases down the group. C The electronegativity of the elements decreases down the group. D The magnitude of the lattice energy of the metal oxides decreases down the group.

3 © Raffles Institution 2022 9729/J/22 [Turn Over 3 Use of the Data Booklet is relevant to this question. A to H are consecutive elements in the Periodic Table with atomic number ≤ 20. The graph below shows the variation in melting point for these eight elements. Which of the following statements are correct? 1 The oxide of B dissolves in water to give an acidic solution while the oxide of H dissolves in water to give an alkaline solution. 2 A and E react together to form a product that dissolves in water to give an acidic solution. 3 Both C and D are solids at room temperature and each forms oxides with different oxidation states. A 2 only C 2 and 3 only B 1 and 3 only D 1, 2 and 3 melting point / °C atomic number ● ● ● ● ● ● ● ● A B C D E F G H

4 © Raffles Institution 2022 9729/J/22 [Turn Over 4 The mechanism for the reaction between reactants A and B is shown below. step 1 2A ⇌ C fast step 2 B + C → D slow step 3 B + D → A2B2 fast What conclusions can be drawn from the information given above? 1 The rate equation for the overall reaction is rate = k[B][C]. 2 The overall equation is 2A + 2B → A2B2. 3 The rate of formation of A2B2 is equal to the rate of depletion of B. A 1 only C 1 and 2 B 2 only D 2 and 3 5 Use of the Data Booklet is relevant to this question. The following enthalpy changes are given. Mg(s) → Mg2+(g) + 2e− ∆H = +2353 kJ mol−1 O2(g) + 4e− → 2O2−(g) ∆H = +1794 kJ mol−1 Which statements are correct? 1 The enthalpy change of atomisation of magnesium is +167 kJ mol−1. 2 The enthalpy change of atomisation of oxygen is +496 kJ mol−1. 3 The sum of the first and second electron affinities of oxygen is +897 kJ mol−1. A 1 only C 2 and 3 only B 1 and 3 only D 1, 2 and 3

5 © Raffles Institution 2022 9729/J/22 [Turn Over 6 Use of the Data Booklet is relevant to this question. In monopropellant engines, hydrazine, NH2NH2, is decomposed as shown below. H H H N H N N≡N (g)3 (l) 4 (g)H H H N + ∆Hr = –330.5 kJ mol−1 What is the enthalpy change of vaporisation of hydrazine? A +44.5 kJ mol−1 B +133.5 kJ mol−1 C +264.8 kJ mol−1 D +1720 kJ mol−1 7 X and Y are acidic solutions with the same pH. When equal volumes of both solutions are separately diluted with the same volume of water, the pH of the resulting solution of X is higher than that of Y. Which pair of acids fits the description above? X Y A HCl CH3COOH B HCl H2SO4 C H2SO4 HCl D CH3COOH HCl 8 Which of the following, when dissolved in 1 dm3 of water, would give the lowest pH? (pKa of CH3COOH = 4.76 and pKb of NH3 = 4.75) A 10−4 mol of HCl B 10−4 mol of CH3COOH C 1 mol of HCl and 1 mol of NH3 D 1.1 mol of CH3COOH and 0.1 mol of NaOH

6 © Raffles Institution 2022 9729/J/22 [Turn Over 9 The values of the solubility product, Ksp, of two calcium salts at 25 ºC are given below. value of Ksp calcium fluoride, CaF2 4.0 × 10−11 calcium carbonate, CaCO3 3.4 × 10−9 Which statement is correct? A The solubility of calcium carbonate decreases with decreasing pH. B Calcium fluoride has a higher molar solubility than calcium carbonate. C Addition of sodium fluoride to a solution containing calcium fluoride decreases the solubility product of calcium fluoride. D When solid calcium nitrate is added into a solution containing F − and CO32− ions, each of concentration 0.1 mol dm−3, CaCO3 precipitates out first. 10 Use of the Data Booklet is relevant to this question. The diagram below shows a cell at 25 °C. Which set of information is correct for this cell? Ecell direction of electron flow A less positive than +1.05 V Ag to Ni B less positive than +1.05 V Ni to Ag C more positive than +1.05 V Ni to Ag D more positive than +1.05 V Ag to Ni Ni [Ni2+(aq)] = 0.5 mol dm−3 salt bridge Ag [Ag+(aq)] = 1.5 mol dm−3 V

7 © Raffles Institution 2022 9729/J/22 [Turn Over 11 The diagram shows the set-up needed to measure the standard electrode potential of a Fe3+/Fe2+ half-cell. Which statement is correct? A The pr