RI 2024 Y5 Promotional Examination QP

Name: ( ) Class: 25S0______ R AFFLES INSTITUTION 2024 YEAR 5 PROMOTION EXAMINATION Hi gher 2 CHEMISTRY 9729 24 September 2024 2 hours 30 minutes Additional Materials: Multiple Choice Answer (OMR) Sheet Data Booklet READ THESE INSTRUCTIONS FIRST Write your name, 6-digit exam index number and class in the spaces provided on the OMR sheet and the cover sheets on pages 1 and 19. Shade your 6-digit exam index number on the OMR sheet. This paper consists of three sections, A, B and C. S ection 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 (35 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 page at the end of the booklet for Section B ( page 18). The question number must be clearly shown. Section C (40 marks) consists of 3 free-response 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 C (page s 31 – 32). The question number must be clearly shown. This document consists of 32 printed pages. Write in dark blue or black pen. You may use a HB pencil for any diagrams or graphs. Do not use staples, paper clips, glue or correction fluid. The us e 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. For Examiner’s Use Only B1 / 14 B2 / 13 B3 / 8 This document is copyrighted, please do not reproduce it without permission

2 © Raffles Institution 2024 9729/S/24 [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 A sample of neon gas was found to contain a mix of three different isotopes, 20Ne, 21Ne and 22Ne. The information in the table was obtained by analysis of the sample. species 20Ne 21Ne 22Ne % abundance 60.9 1.2 37.9 Which Ar value for neon is given by these figures? A 20.2 B 20.5 C 20.8 D 21.0 2 When a sample of hydrocarbon, C xHy, was combusted in an excess of oxygen, 0.06 mol of carbon dioxide and 0.04 mol of water were obtained. What could be the values of x and y? x y A 3 6 B 6 10 C 6 12 D 9 12 3 Use of the Data Booklet is relevant to this question. W, X and Y are isotopes of three different elements. An isotope of strontium, a Group 2 element, has a nucleon number of 84 and the same number of neutrons in the nucleus as each of the isotopes W, X and Y. The species Sr 2+, W, X− and Y2− all contain the same number of electrons. What are the nucleon numbers of W, X and Y? W X Y A 80 81 82 B 82 81 80 C 82 83 84 D 84 83 82 This document is copyrighted, please do not reproduce it without permission

3 © Raffles Institution 2024 9729/S/24 [Turn Over 4 In which pair of substances is the boiling point of the first substance higher than that of the second substance? first substance second substance A K Na B CO2 SiO2 C NH2HO CH3HO D C CH3 CH3 CH3 CH3 CH3CH2CH2CH2CH3 5 Which statement is correct about the ethanoate ion, CH3COO−? A It is a planar ion. B The π electrons are delocalised over all atoms. C The two carbon−oxygen bonds have different bond lengths. D The H−C−H bond angle is smaller than the C−C−O bond angle. 6 The standard enthalpy change of combustion of methane is −890 kJ mol−1. CH4(g) + 2O2(g) → CO2(g) + 2H2O(l) Values of the relevant average bond energies are given in the table. average bond energy / kJ mol−1 C−H C=O O−H O=O 410 805 460 496 What is the value for the standard enthalpy change of vaporisation of water? H2O(l) → H2O(g) A −72 kJ mol−1 B −36 kJ mol−1 C +36 kJ mol−1 D +72 kJ mol−1 This document is copyrighted, please do not reproduce it without permission

4 © Raffles Institution 2024 9729/S/24 [Turn Over 7 Which graph about the behaviour of an ideal gas is correct? A B C D pV V T / K p 1 V p n p constant n and T constant n and V constant n and T constant V and T This document is copyrighted, please do not reproduce it without permission

5 © Raffles Institution 2024 9729/S/24 [Turn Over 8 Which equation correctly represents the lattice energy of sodium oxide? A 2Na(s) + ½O2(g) → Na2O(s) B 2Na+(g) + O2−(g) → Na2O(s) C Na2O(s) → 2Na+(g) + O2−(g) D Na2O(s) → 2Na(g) + O(g) 9 The equation below shows the decomposition of magnesium carbonate. MgCO3(s) → MgO(s) + CO2(g) ∆H = +118 kJ mol−1 Which statement is correct for this reaction? A The reaction is only spontaneous at high temperatures. B The reaction is only spontaneous at low temperatures. C The reaction is not spontaneous at all temperatures. D The reaction is spontaneous at all temperatures. 10 The kinetics of the reaction between I− and S2O82− ions can be investigated by varying the volume of the reactants used. The two reactants are mixed in the presence of Na 2S2O3 and starch solution. S2O82−(aq) + 2I−(aq) → 2SO42−(aq) + I2(aq) When all the Na2S2O3 has reacted with the I2 produced, an intense blue colour will be observed. The time taken for the blue colour to appear is recorded. What is the time taken, in seconds, for the intense blue colour to be observed for experiment 4? experiment volume used / cm3 time / s 1.0 mol dm−3 I− 0.080 mol dm−3 S2O82− 1.0 mol dm−3 S2O32− H2O 1 10.0 5.0 2.0 23.0 85.0 2 20.0 5.0 2.0 13.0 42.5 3 10.0 15.0 2.0 13.0 28.5 4 40.0 20.0 4.0 16.0 ? A 5.3 B 10.6 C 21.3 D 42.5 This document is copyrighted, please do not reproduce it without permission

6 © Raffles Institution 2024 9729/S/24 [Turn Over 11 Phosgene can be synthesised via the following reaction. Cl2(g) + CO(g) → COCl2(g) The proposed mechanism for the reaction is given below. step 1 Cl2 ⇌ 2Cl (fast) step 2 CO + Cl → COCl (slow) step 3 COCl + Cl → COCl2 (fast) Which conclusions can be drawn from this information? 1 Overall order of reaction is 1.5. 2 An increase in the partial pressure of Cl2 will decrease the reaction rate. 3 The units for the rate constant of the reaction is the same as the units of the equilibrium constant of step 1. A 1 only B 1 and 2 C 1 and 3 D 2 and 3 12 When an equimolar mixture of H 2(g) and I2(g) react, the mole fraction of H I(g) in the final mixture is 2x. H2(g) + I2(g) ⇌ 2HI(g) What is the equilibrium constant, Kp, for the reaction? A 4x2 (1 − x)2 B 16x2 (1 − x)2 C 4x2 (1 − 2x)2 D 16x2 (1 − 2x)2 13 In a reaction vessel, N 2 and H2 are allowed to react to form NH 3, as shown in the equation below. N2(g) + 3H2(g) ⇌ 2NH3(g) ∆H < 0 Which change to the conditions will increase the rate of formation of NH 3 and increase the percentage composition of NH3 in the mixture? A adding iron catalyst B decreasing the temperature C reducing the total volume at constant t