CJC Prelim P1

1 CANDIDATE NAME CLASS 2T CHEMISTRY 9729/01 Paper 1 Multiple Choice Wednesday 29 August 2018 1 hour Additional Materials: Mult iple Choice Answer Sheet Data Booklet READ THESE INSTRUCTIONS FIRST Write in soft pencil. Do not use staples, paper clips, glue or correction fluid. Write your name, class and NRIC/FIN number on the Answer Sheet in the spaces provided. There are thirty questions on this paper. 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 this booklet. The use of an approved scientific calculator is expected, where appropriate. This document consists of 16 printed pages. Catholic Junior College JC 2 Preliminary Examinations Higher 2

2 9729/01/CJC JC2 Preliminary Examination 2018 1 A sample of tungsten contains four naturally occurring isotopes, 182W, 183W, 184W and 186W. The relative atomic mass of tungsten in this sample is 183.9. What is the percentage of the isotope 182W in this sample? Isotope Relative Abundance (%) 182W ? 183W ? 184W 30.6 186W 28.6 A 10.5 C 26.4 B 14.4 D 40.8 2 20 cm 3 of 0.100 mol dm −3 of potassium ferrate( VI), K 2FeO4, reacts with sodium ethanedioate, Na2C2O4, in an acidic medium to produce 144 cm 3 of carbon dioxide gas at room temperature and pressure. The half equation of C2O42– is shown as follows: 2CO2 + 2e– C 2O42– What is the final oxidation state of the iron-containing species after the reaction? A +1 B +2 C +3 D +4 3 When attracted by a strong magnet, some species are able to exhibit paramagnetism. Such species contain unpaired electrons which are able to spin in a way which aligns parallel to the magnetic field. Which of the following species in the ground state is able to exhibit paramagnetism? 1 O 2 A l+ 3 Ti2+ 4 Cu+ A 1 and 3 only B 2 and 4 only C 1, 3 and 4 only D 2, 3 and 4 only

3 9729/01/CJC JC2 Preliminary Examination 2018 [Turn over 4 Phosphorus(V) chloride, PCl5 dissolves in a suitable polar solvent to produce two ions, [PCl4]+ and [PCl6]–. Which of the following shows the correct shape for PCl5, [PCl4]+ and [PCl6]–? PCl5 [PC l4]+ [PC l6]– A trigonal planar square planar square pyramidal B trigonal bipyramidal square planar octahedral C trigonal planar distorted tetrahedral square pyramidal D trigonal bipyramidal tetrahedral octahedral 5 The table shows the boiling point of some halogenoalkanes. compound boiling point/ °C CH3CH2Cl 12.3 CH3CH2Br 34.8 CH3CH2I 70.0 Which of the following correctly explains the difference in the boiling point? 1 the electronegativity difference between the halogen and carbon increases from C−Cl to C−I 2 the strength of permanent dipole-permanent dipole attraction increases from C −Cl to C−I 3 the strength of instantaneous dipole-induced dipole attraction increases from CH3CH2Cl to CH3CH2I 4 the bond energy of C−X bond decreases from C−Cl to C−I A 1 and 2 only B 2 and 4 only C 3 only D 3 and 4 only

4 9729/01/CJC JC2 Preliminary Examination 2018 6 Which of the following changes will result in the greatest decrease in the density of a fixed mass of ideal gas? Pressure Temperature/ K A halves halves B halves doubles C doubles halves D doubles doubles 7 Consider the following reactions. Reaction 1: CH3+ + Br – → CH3Br Reaction 2: HPO42− + H2BO3− H 2PO4− + HBO32− Which of the following statement is not true about the reactions above? A Both reactions are acid-base reactions. B In reaction 2, HPO42− acts as the Brønsted-Lowry base. C In reaction 2, HBO32− is the conjugate acid of H2BO3−. D In reaction 1, a dative covalent bond is formed between CH3+ and Br – . 8 Which of the following sketches shows the correct trend in the stated property for the elements in the third period of the Periodic Table? A C B D Na Mg Al Si P S Cl Atomic Radius / nm Na Mg Al Si P S Cl First I.E / kJ mol−1 Na Mg Al Si P S Cl Melting Point / °C Na Mg Al Si P S Cl Electrical Conductivity / S m−1

5 9729/01/CJC JC2 Preliminary Examination 2018 [Turn over 9 Compounds of Period 3 elements dissolve in water to form aqueous solutions that are acidic, basic or neutral. Which of the following sequence shows the order of increasing resultant pH when the compounds are added to water? A NaC l, MgCl2, SiCl4 C Al2O3, MgO, SO2 B AlCl3, SiCl4, PCl5 D P4O10, SiO2, MgO 10 Phosphine reacts with hydrogen iodide to form phosphonium iodide in the reaction shown below: PH3(g) + HI(g) → PH4+I−(s) ∆Ho = −145.2 kJ mol−1; ∆So = −570.8 J K−1 mol−1 Which of the following statement is true for the above reaction? 1 The products are less disordered than the reactants. 2 The reaction is non-spontaneous under standard conditions. 3 As temperature increases, the reaction becomes more spontaneous. A 1 only B 2 only C 1 and 2 only D 1, 2 and 3 only 11 The reaction of acidified aqueous potassium iodide with aqueous hydrogen peroxide: 2I−(aq) + H2O2(aq) + 2H+(aq) → I2(aq) + 2H2O(l) is thought to involve the following steps: H2O2 + I− → H2O + OI− ( s l o w ) OI− + H+ → HOI ( f a s t ) HOI + H+ + I− → I2 + H2O (fast) Which of the following conclusion can be drawn from this information? 1 The acid is acting as a catalyst only. 2 The reaction is pseudo-first order with respect to H 2O2. 3 The reaction rate is independent of the pH of the solution. A 1 only B 3 only C 1 and 2 only D 1,2 and 3 only

6 9729/01/CJC JC2 Preliminary Examination 2018 12 A first-order decomposition reaction is shown below. AB(g) → A(g) + B(g) The half-life of the reaction was found to be 3.47 s. What is the time taken for AB(g) to reach one-third of its initial concentration? A 3.0 s B 3.5 s C 5.5 s D 7.0 s 13 The graph below shows how the number of moles of compound L varies with temperature at two different pressures of P1 and P2 respectively. L could be any of the following compounds shown in the equation at equilibrium. 2SO2(g) + O2(g) 2SO 3(g) ∆H = –197 kJ mol−1 What is the correct identity of L and the correct magnitude of pressures P 1 and P2? Identity of L magnitude of pressures P1 and P2 A SO2 P1 > P2 B SO2 P1 < P2 C SO3 P1 > P2 D SO3 P1 < P2 No. of moles of L Temperature

7 9729/01/CJC JC2 Preliminary Examination 2018 [Turn over 14 When nitrogen dioxide, NO 2, and nitrogen monoxide, NO, is mixed, the gases react to form dinitrogen trioxide, N2O3. The reaction is shown in the following equilibrium. N O 2(g) + NO(g) N 2O3(g) The graph below shows how the ΔGo varies with temperature for the above reaction. Using the graph above, deduce which of the following statement is true about the reaction at equilibrium? A At point X, more NO 2 is present as compared to that at point Y. B At point X, the Kc value is likely to be greater than 1. C At point Y, the rate of forward reaction is greater than that of backward reaction. D At point Z, more N2O3 is present compared to that at point Y. 15 The pH changes when 0.100 mol dm −3 CH 3CO2H is added dropwise to 10.0 cm 3 of 0.100 mol dm−3 NaOH(aq) as shown below. At which point on the graph does pH = p Ka, where Ka is the acid dissociatio