RI 2018 Prelim P1 QP

© Raffles Institution 2018 9729/01/S/18 [Turn Over RAFFLES INSTITUTION 2018 YEAR 6 PRELIMINARY EXAMINATION Higher 2 CHEMISTRY 9729/01 Paper 1 Multiple Choice 24 September 2018 1 hour Additional Materials: Multiple Choice Answer Sheet Data Booklet READ THESE INSTRUCTIONS FIRST Do not open this question booklet until you are told to do so. Write in soft pencil. Do not use staples, paper clips, highlighters, glue or correction fluid. Write your name, class and index number in the spaces provided on the Answer Sheet. There are thirty questions in this section. Answer all questions. 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 separate Answer Sheet. Read the instructions on the Answer Sheet very carefully. 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 booklet. This document consists of 18 printed pages.

© Raffles Institution 2018 9729/01/S/18 [Turn Over 2 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 iron contains three isotopes : iron-54, iron-56 and iron-58. Its relative atomic mass is 55.849. One of the isotopes has a percentage abundance of 91.8%. isotope accurate isotopic mass percentage abundance iron-54 53.94 x iron-56 55.94 y iron-58 57.93 z Which row gives the correct values of x, y and z? x y z A 91.8 6.37 1.83 B 1.83 91.8 6.37 C 6.37 91.8 1.83 D 1.83 6.37 91.8 2 S2Clx disproportionates completely in water to give S and SO2 in the ratio of 3:1. What is the value of x? A 2 C 6 B 4 D 8 3 Which ion would undergo the greatest deflection in an electric field? A 15N2+ C 12C16O2+ B 12C16O23+ D 16O18O2+

© Raffles Institution 2018 9729/01/S/18 [Turn Over 3 4 The radioactive isotope Am95 241 is a synthetic isotope used in ioni sation smoke detectors. Am95 241 decays to give an element E and emits a high energy 𝛼-particle (which is a helium nucleus, He2 4 ). No other particle is produced. Am95 241 → He2 4 + E Which row in the table correctly describes the nuclear make-up of element E? number of protons number of neutrons A 91 144 B 91 237 C 93 144 D 93 237 5 Which statement about both molecules shown below is correct? A Both can turn hot acidified potassium dichromate(VI) from orange to green. B G can form intramolecular hydrogen bonding while F cannot. C Both molecules have the same number of  electrons. D Both molecules are planar.

© Raffles Institution 2018 9729/01/S/18 [Turn Over 4 6 Which graph represents the correct behaviour for a fixed mass of an ideal gas? (Assume that all temperatures are measured in Kelvin.) A C B D

© Raffles Institution 2018 9729/01/S/18 [Turn Over 5 7 Use of the Data Booklet is relevant to this question. Methane undergoes free radical substitution with bromine in the presence of UV light. Which energy profile diagram represents the propagation steps that lead to the formation of bromomethane? A C B D 8 Which is not a trend from left to right across the elements of the third period of the Periodic Table? A The maximum oxidation number increases. B The melting point of the oxides decreases. C The pH of the aqueous solutions of the chlorides decreases. D The nature of bonding of the chlorides change from ionic to covalent.

© Raffles Institution 2018 9729/01/S/18 [Turn Over 6 9 Elements J, K and L are elements in Period 3 of the Periodic Table. The melting point of element J is higher than that of element K. Only the oxide of element L is insoluble in water. Which row in the table gives the correct identities of elements J, K and L? J K L A Cl P Mg B Na Mg Si C P S Al D S P Si 10 The reaction between NO2 and SO2 is a key stage in the formation of acid rain. NO2(g) + SO2(g) ⎯→ NO(g) + SO3(g) A series of experiments was conducted with various concentrations of NO 2 and SO2 in the absence of air. experiment [NO2] / mol dm−3 [SO2] / mol dm−3 relative rate 1 0.010 0.20 1 2 0.020 0.20 2 3 0.040 0.40 8 The half-life of NO2 in experiment 1 was 48 seconds. Which row gives the correct half-life of NO2 in experiments 2 and 3? half-life in experiment 2 half-life in experiment 3 A 24 s 6 s B 24 s 24 s C 48 s 24 s D 48 s 48 s

© Raffles Institution 2018 9729/01/S/18 [Turn Over 7 11 A pink coloured compound, M, reacts with OH− to give a colourless compound, N. A series of experiments was carried out using different volumes of the 2 reagents, M(aq) and NaOH(aq). The following results were obtained. experiment volume of 0.001 mol dm−3 M / cm3 volume of 0.1 mol dm−3 NaOH / cm3 volume of water / cm3 time taken for pink colour to fade / s 1 1 10 4 100 2 2 10 3 100 3 1 5 9 200 4 2 20 8 ? Which conclusions follow from these results? 1 The reaction is first order with respect to M. 2 The reaction is first order with respect to OH−. 3 The time taken for the pink colour to fade in experiment 4 was 50 s. A 1 and 2 C 1 and 3 B 2 and 3 D 1, 2 and 3

© Raffles Institution 2018 9729/01/S/18 [Turn Over 8 12 Consider the following reversible reaction. Q(g) + R(g) ⇌ S(g) ΔH < 0 After equilibrium was reached, the system was disturbed and the change s to the system were monitored. The changes were as follows. [S] Kp rate of forward reaction rate of backward reaction increased unchanged increased increased What was the disturbance applied? A addition of a catalyst B increase in temperature C compression of reaction mixture D addition of an inert gas at constant volume 13 The graph below shows how the fraction of NH3(g) in the equilibrium mixture of the Haber process varies with temperature at pressures of p1 and p2. N2(g) + 3H2(g) ⇌ 2NH3(g) ΔHr = x kJ mol−1 Which row in the table is correct? A x < 0 p1 > p2 B x < 0 p1 < p2 C x > 0 p1 > p2 D x > 0 p1 < p2

© Raffles Institution 2018 9729/01/S/18 [Turn Over 9 14 Use of the Data Booklet is relevant to this question. Which expression gives the pH of a 0.2 mol dm−3 NH3(aq) solution at 25 °C? (Ka of NH4+ = 5.6 × 10−10 mol dm−3) A − lg√0.2 × 5.6 × 10−10 B 14 + lg√0.2 × 5.6 × 10−10 C − lg√0.2 × 1.0 × 10−14 5.6 × 10−10 D 14 + lg√0.2 × 1.0 × 10−14 5.6 × 10−10 15 Which pairs of substances, when mixed in equal volumes, produce a buffer solution? 1 0.05 mol dm−3 HCl(aq) and 0.08 mol dm−3 Na3PO4(aq) 2 0.05 mol dm−3 CH3CO2H(aq) and 0.08 mol dm−3 NaOH(aq) 3 0.08 mol dm−3 HO2C–CO2H(aq) and 0.05 mol dm−3 NaOH(aq) A 1 only C 2 and 3 B 1 and 3 D 1, 2 and 3

© Raffles Institution 2018 9729/01/S/18 [Turn Over 10 16 Iron can form complexes with variable oxidation states. Which row gives the incorrect oxidation number of Fe in the iron complex? iron complex oxidation number of Fe A +4 B 0 C +3 D +3