AJC Prelims H2 Chem Paper1 Question paper

AJC/H2 Chemistry/Prelims2008 [Turn over 1 ANDERSON JUNIOR COLLEGE Preliminary Examination 2008 CHEMISTRY 9746/01 Higher 2 15 Sep 2008 Paper 1 Multiple Choice 1 hour Additional Materials: Multiple Choice Optical Answer Sheet Data Booklet READ THESE INSTRUCTIONS FIRST Write in soft pencil. Do not use staples, paper clips, highlighters, glue or correction fluid. There are forty 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 Optical Answer 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 this booklet. Optical Answer Sheet Write your name and PDG. Shade the last 5 digits of your NRIC / FIN number. DO NOT shade the reference letter. This document consists of 14 printed pages.

AJC/H2 Chemistry/Prelims2008 [Turn over 2 Section A For each question there are four possible answers, A, B, C and D. Choose the one you consider to be correct. 1 To determine the mass of arsenic present in a sample of pesticide, all the arsenic was first converted to arsenate ion, AsO 4 3-. 1.25 × 10-3 moles of AgNO 3 was then added to precipitate AsO4 3- as Ag3AsO4. The excess Ag + ions needed 3.64 cm 3 of 0.054 mol dm -3 KSCN to form silver thiocyanate, AgSCN. Calculate the mass of arsenic (A r = 74.9) present in the sample of pesticide. A 0.015 g B 0.026 g C 0.079 g D 0.488 g 2 An aqueous solution contains 1 mole of S2O3 2- ions and this reduces 4 moles of Cl2 molecules. What is the sulphur-containing product of this reaction? A SO2 B SO3 2- C SO4 2- D S4O6 2- 3 Three identical flasks each contains the same mass of gases E, F and G respectively. The temperature and pressure of each flask are indicated below. Temperature / oC t Gas E Gas F Gas G t 2t Pressure / atm p 2p p Assuming ideal gas behaviour, which of the followi ng is a correct representation of the relative molecular masses of the three gases? A Mr(G) > Mr(E) > Mr(F) B Mr(G) > Mr(F) > Mr(E) C Mr(E) > Mr(F) > Mr(G) D Mr(E) > Mr(G) > Mr(F) 4 The ion X2+ has 54 electrons and 81 neutrons. Which of the following statements is true? A Element X is isoelectronic with xenon. B The first ionization energy of element X is higher than that of Mg. C The oxide of X formed is expected to have a higher melting point than MgO. D In an electric field, the ion X2+ will be deflected at a smaller angle than that of Mg2+. 5 Which of the following statements cannot be explained by hydrogen bonding? A Ice has a density lower than water at 0 oC. B The boiling point of 2-nitrophenol is lower than that of 4-nitrophenol. C The boiling point of ethanal is higher than dimethyl ether, CH3OCH3. D The relative molecular mass of ethanoic acid is 120 when dissolved in benzene.

AJC/H2 Chemistry/Prelims2008 [Turn over 3 6 Which of the following pairs of substances does not include a giant structure and a simple molecular structure? A aluminum and silicon(IV) oxide B aluminium oxide and aluminium chloride C silicon and chlorine D silicon and silicon(IV) chloride 7 Given the following enthalpy changes CH3CH3 CH3CH2• + H• ∆H = +412 kJ mol-1 CH3CH2• CH2=CH2 + H• ∆H = +168 kJ mol-1 What is the enthalpy change of the following reaction? 2 CH 3CH2• CH3CH3 + CH2=CH2 A +412 kJ mol-1 B +244 kJ mol-1 C –244 kJ mol-1 D –412 kJ mol-1 8 A simple rechargeable battery is constructed by dipping two lead electrodes into aqueous lead(II) nitrate and passing current through it for a few minutes. When it is fully charged, lead(IV) oxide is deposited on one of the electrodes. During normal usage, a voltage of +1.60V is produced and the following reactions occur: Anode: Pb Pb2+ + 2e Cathode: PbO 2 + 4H+ + 2e Pb2+ + 2H2O Which of the following changes can be made to the cell to increase the e.m.f.? A Increasing the size of the lead electrodes B Using a higher current during charging of the battery C Using a higher concentration of lead(II) nitrate D Replacing the electrolyte with dilute sulphuric acid 9 The circuit shown in the diagram was set up. Which reactions will occur at the electrodes? anode reaction cathode reaction A Oxygen gas is evolved. Hydrogen gas is evolved. B Tin dissolves preferentially. Hydrogen gas is evolved. C Copper dissolves preferentially. Copper is deposited. D Copper and tin both dissolve. Sulphur dioxide gas is evolved. dilute sulphuric acid an alloy of copper and tin platinum

AJC/H2 Chemistry/Prelims2008 [Turn over 4 10 The following reaction is used industrially to produce a combustible gas from coal. H2O(g) + C(s) H2(g) + CO(g) At equilibrium, the partial pressure of each gaseous species is p atm at 500 oC. When the total pressure of the system was increased at the sa me temperature, the partial pressure of the H2O(g) increased to 4p atm at the new equilibrium. What would be the partial pressure of CO(g) at the new equilibrium? A 0.5p atm B p atm C 2p atm D 4p atm 11 J and L can react together to reach equilibrium in the reaction below. J(g) + L(g) M(g) + N(g) In an experiment, 1.0 mole each of J and L were reacted at constant pressure P and temperature 350 oC. The amount of N present in the mixture was recorded at regular intervals of time. The experiment was repeated at the same pressure P, but at a temperature of 700 oC. The results for both experiments are shown below. time Which of the following information cannot be deduced from the graph? A The activation energy of the forward reaction is high. B The forward reaction is exothermic. C The value of K p at 350 oC is 5.44. D The time taken for the equilibrium to be achieved is shorter at higher temperatures. 12 A solution, saturated with Ca(OH)2 and CaSO4, has a pH of 12.3. What is the concentration, in mol dm-3, of SO4 2- ions in the solution? (Ksp value of Ca(OH)2 = 4.0 x 10-5, Ksp value of CaSO4 = 2.5 x 10-5) A 1.25 x 10-4 B 2.50 x 10-4 C 1.25 x 102 D 2.50 x 102 350 oC number of moles of N 700 oC0.4 0.6 0.8 1.0 0.0 0.2

AJC/H2 Chemistry/Prelims2008 [Turn over 5 13 The pH change when 0.100 mol dm -3 CH3COOH is added dropwise to 10.0 cm 3 of 0.100 mol dm -3 NaOH(aq) is shown below. At which point on the graph does pH = pK a, where Ka is the acid dissociation constant of the weak acid? 0 2 4 6 8 10 12 14 0 2 4 6 8 1 01 21 41 61 82 0 volume of 0.100 mol dm -3 CH3COOH added/cm 3 pH 14 For the reaction P + 2Q Æ R + S, the rate equation is found experimentally to be: rate = k[P] If the reaction is carried out using excess P, which of the following graphs most correctly represents the change in concentration of Q with time? A B C D A B C D [Q] time 0 [Q] time 0 0 [Q] time 0 [Q] time

AJC/H2 Chemistry/Prelims2008 [Turn over 6 15 Beryllium resembles aluminium in its chemical properties. Which property of beryllium compounds is unlikely to be correct? A Beryllium oxide can undergo reaction with acids. B Beryllium oxide can undergo reaction with alkali. C Beryllium chloride can form a dimer. D Beryllium chl