2019 HCI Prelim H2 Chem P1 QP

This document consists of 12 printed pages. HWA CHONG INSTITUTION C2 Preliminary Examinations Higher 2 CANDIDATE NAME CT GROUP 18S CENTRE NUMBER INDEX NUMBER CHEMISTRY Paper 1 Multiple Choice Additional Materials: Multiple Choice Answer Sheet Data Booklet 9729/01 25 September 2019 1 hour READ THESE INSTRUCTIONS FIRST Write in soft pencil. Do not use staples, paper clips, glue or correction fluid. Complete the information on the Answer Sheet as shown below. There are 30 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 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.

© Hwa Chong Institution 2019 9729 / 01 / C2 Prelim 2019 2 1 Which statement about relative atomic mass is correct? A It is the average of the masses of all the isotopes of that element. B It is the sum of the relative masses of the neutrons and protons in each atom. C It is the ratio of the average mass of one atom of an element to the mass of one 1H atom. D It is the ratio of the mass of one mole of atoms of an element to one-twelfth the mass of one mole of 12C atoms. 2 Which of the graphs correctly represent the trends in some properties of the Period 3 elements? 1 2 3 4 A 1 and 2 B 2 and 3 C 3 and 4 D 1, 2 and 4 electronegativity Na Mg Al Si P S Cl atomic radii Na Mg Al Si P S Cl electrical conductivity Na Mg Al Si P S Cl melting point Na Mg Al Si P S Cl

© Hwa Chong Institution 2019 9729 / 01 / C2 Prelim 2019 3 3 Which of the following correctly describes the structure and bonding present in the solid lattice of the substances given? substance structure bonding A ice giant covalent covalent bonding + hydrogen bonding B iodine simple covalent covalent bonding + permanent dipoles C aluminium chloride giant ionic ionic bonding + permanent dipoles D graphite giant covalent covalent bonding + dispersion forces 4 In which of the following pairs is the bond angle in the first species smaller than that in the second species? A NH4+ XeF4 B NF3 NH3 C NO2+ SO2 D BCl3 PCl3 5 A container with a volume of 420 m3 with an internal pressure of 1 bar at 293 K was joined to two containers as shown below. One of them has a volume of 13 m 3 with a vacuum within, while the other has a volume of 75.5 m 3 with an internal pressure of 2 bar and a temperature of 273 K. What is the final pressure, in bar, in the combined containers when the taps were opened and the temperature allowed to equilibrate to 298 K? A 0.84 B 1.12 C 1.16 D 1.19 420 m3 1 bar 293 K 13 m3 vacuum 75.5 m3 2 bar 273 K taps

© Hwa Chong Institution 2019 9729 / 01 / C2 Prelim 2019 4 6 Use of the Data Booklet is relevant to this question Sodium percarbonate, (Na 2CO3)x•y(H2O2), is an oxidising agent in some home and laundry cleaning products. 10.0 cm3 of 0.100 mol dm–3 sodium percarbonate releases 45.4 cm3 of carbon dioxide at s.t.p. on acidification. An identical sample, on titration with 0.05 mol dm–3 KMnO4, requires 24.0 cm3 before the first pink colour appears. KMnO4 reacts with H2O2 in the mole ratio 2 : 5. What is the ratio y x ? A 1 3 B 2 3 C 3 2 D 3 1 7 Which statement correctly explains why the change in Gibbs’ free energy of the reaction below is relatively constant when the temperature changes? 2HX(g) ⇌ H2(g) + X2(g) A S is almost zero for all temperatures in which the reactants and products are gases. B The equilibrium constant is not affected by a temperature change. C H and S do not change with temperature, hence G remains constant. D The equilibrium position will shift in such a way to offset the changes in temperature. 8 The conversion of diamond into graphite is an exothermic reaction. C(diamond)  C(graphite) H < 0         G < 0 Which statements are correct? 1 The magnitude of the enthalpy change of atomisation of graphite is greater than that for diamond. 2 The magnitude of the enthalpy change of combustion of graphite is greater than that for diamond. 3 The bond energy of the C–C bonds in graphite is greater than that for diamond. 4 The conversion of diamond to graphite does not take place readily due to the high activation energy. A 1 and 2 B 1, 3 and 4 C 2, 3 and 4 D 1, 2, 3 and 4

© Hwa Chong Institution 2019 9729 / 01 / C2 Prelim 2019 5 9 Thorium-234 undergoes radioactive decay to form pro tactinium-234 by emitting a beta particle. This radioactive decay is a first order reaction with a half-life of 24.1 hours. A rock sample contains a 2 : 3 molar proportion of thorium-234 to protactinium-234. How many hours has the radioactive decay taken place if the sample was initially protactinium-234 free? A 14.1 B 24.1 C 31.9 D 60.3 10 Which suggested mechanism is consistent with the experimentally determined rate equation? rate equation suggested mechanism 1 rate = k[NO]2[H2] 2NO + H2  N2O + H2O slow N2O + H2  N2 + H2O fast 2 rate = k[O2][N2O2] 2NO  N2O2 fast N2O2 + O2  2NO2 slow 3 rate = k[O3][Cl] Cl + O3  OCl + O2 slow OCl + O3  2O2 + Cl fast A 1 and 2 B 1 and 3 C 2 and 3 D 1, 2 and 3 11 The key stage in the manufacture of sulfuric acid is the reaction between sulfur dioxide and oxygen to form sulfur trioxide. 2SO2(g) + O2(g) ⇌ 2SO3(g) When 0.50 mol of SO2 and 1.00 mol of O2 were reacted together in a container of volume 0.5 dm3, 0.30 mol of SO3 was present in the equilibrium mixture. What is the numerical value of the equilibrium constant, Kc, for the equilibrium reaction below? SO2(g) + 1 2O2(g) ⇌ SO3(g) A 0.66 B 1.15 C 1.32 D 1.63 12 Which statement about the effect of adding a catalyst to a reversible reaction is correct? A It increases the yield of product in the reaction. B It increases the rate constant for the forward reaction. C It increases the equilibrium constant of the forward reaction. D It increases the activation energy of the reverse reaction.

© Hwa Chong Institution 2019 9729 / 01 / C2 Prelim 2019 6 13 Which graphs correctly show how the values of pH,  (degree of dissociation) and Ka for a weak acid vary with dilution at constant temperature? 1 2 3 A 1 only B 1 and 2 C 2 and 3 D 1, 2 and 3 14 Aluminium objects are surface treated by means of anodisation to increase the thickness of the corrosion resistant oxide layer. Which factor will affect the mass of the oxide coating in the anodisation process? A size of the current B size of the cathode C concentration of electrolyte D surface area of the aluminium object 15 Compound V has the molecular formula C6H14O. V has an aliphatic carbon skeleton that is branched and contains a secondary alcohol functional group. How many constitutional isomers fit this description of V? A 2 B 3 C 4 D 5 pH volume of water added 7  1 Ka volume of water added volume of water added

© Hwa Chong Institution 2019 9729 / 01 / C2 Prelim 2019 7 16 Tamoxifen is an important drug used in the prev