MI H2 Chem 2013 Prelim P1 QP

Class Adm No Candidate Name: This document consists of 19 printed pages and 1 blank page. [Turn over 2013 Preliminary Examination II Pre-university 3 H2 CHEMISTRY 9647/01 Paper 1 Multiple Choice Tuesday, 24 Sep 2013 1 hour Additional Materials: Multiple Choice Answer Sheet Data Booklet READ THESE INSTRUCTIONS FIRST Write in soft pencil. Do not use staples, paper clips, highlighters, glue or correction fluid. Write your name, subject class and registrati on number on the Answer Sheet in the spaces provided unless this has been done for you. 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 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. 784

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 Which mass of gas would occupy a volume of 3 dm 3 at room temperature and pressure? A 3.2 g O2 gas C 8.0 g SO2 gas B 5.6 g N2 gas D 11.0 g CO2 gas 2 When an excess of K I solution was added to 10.0 cm 3 of a 0.200 mol dm –3 solution of JO4 3–, the iodine liberated was titrated against a standard solution of 0.100 mol dm –3 of sodium thiosulfate, Na2S2O3, using starch as the indicator. 2S2O3 2– + I2  S4O6 2– + 2I– If the volume of sodium thiosulfate required to discharge the blue–black colouration is 40.00 cm 3, what is the final oxidation state of J? A +1 C +3 B +2 D +4 3 The nickel–cadmium rechargeable battery is based on the following overall reaction: Cd + 2NiOOH + 4H2O → Cd(OH)2 + 2Ni(OH)2.H2O What is the oxidation number of nickel at the start and at the end of the reaction? Beginning End A +2 +2 B +2 +3 C +3 +2 D +3 +4 785

[Turn over 3 4 Use of the Data Booklet is relevant to this question. What could be the proton number of an element that has three unpaired electrons in each of its atoms? A 5 C 15 B 13 D 21 5 C 2H4 and C 2H2 are unsaturated hydrocarbons. Which of the following statements is correct regarding these two molecules? A Both C2H4 and C2H2 have the same shape. B C2H4 has more  bonds but fewer  bonds than C2H2. C The carbons in C2H4 and C2H2 are sp and sp2 hybridised respectively. D The carbon–carbon–hydrogen bond angle is larger in C2H4 than in C2H2. 786

4 6 Which graph correctly describes the behaviour of fixed masses of the ideal gases I and J, where I has a higher Mr than J? A B C D T PV Constant P I J Constant T J I PV P Constant T I J PV P T PV Constant P J I / K / K 787

[Turn over 5 7 Consider the equilibrium 3J2(g) + 2KJ(g) 2KJ4(g). When 4 mol of KJ4 was put into a 2 dm3 container and heated, the equilibrium mixture contained 0.8 mol of KJ. What is the numerical value of the equilibrium constant, Kc? A 74.1 B 9.23 C 1.16 D 0.108 8 Graphite and diamond are two allotropes of carbon. Although graphite is thermodynamically more stable than diamond at 25 C and 1 atm, a piece of diamond will not transform into graphite, even over a period of one million years. Which of the following correctly explains this observation? A G for the reaction diamond  graphite is greater than zero. B H for the reaction diamond  graphite is greater than zero. C The reverse reaction graphite  diamond proceeds quickly. D The reaction diamond  graphite has a large activation energy. 9 Which combination of substances, when dissolved in 10 dm 3 of water, would give a buffer solution? A 1 mol HCl and 1 mol of CH3COOH B 1 mol CH3COOH and 1 mol of CH3COONa C 1 mol HCl and 1 mol of CH3COONa D 1 mol of CH3COOH and 1 mol of NaCl 788

6 10 The reaction between X and Y is an overall second–order reaction. X + Y  Z where Rate = k[X][Y] The rate of this reaction is plotted against the product [ X][Y] of the concentrations of X and Y. Which graph would be obtained? A Rate [X][Y] B Rate [X][Y] C Rate [X][Y] D Rate [X][Y] 789

[Turn over 7 11 The Boltzmann distribution shows the number of molecules having a particular kinetic energy at constant temperature. If the temperature is decreased by 20 °C, what happens to the size of the areas labelled X, Y and Z? X Y Z A Increase Decrease Increase B Increase Decrease Decrease C Decrease Increase Increase D Decrease Increase Decrease 12 The reactivity of the Group II metals with oxygen increases down the group. Which statement best explains this trend? A Electronegativity of the elements decreases down the group. B Ionic radii of the metal cations increase down the group. C Lattice energy of the metal oxides decreases down the group. D Reducing power of the elements increases down the group. Ea Number of molecules having a particular kinetic energy 790

8 13 The diagram below shows the visible spectra of two chromium (III) complexes, CrL6 3+ and CrJ 6 3+. The various colours corresponding to the approximate wavelengths in the visible light region are shown below the axis. What is the colour of each complex and which ligand causes a larger d-orbital splitting? colour of CrL6 3+ colour of CrJ6 3+ ligand which causes a larger d-orbital splitting A blue yellow orange L B blue yellow orange J C red violet L D red violet J 14 Below is a scheme of reaction for a salt T. What is T? A chromium(III) chloride B chromium(III) sulfate C copper(II) chloride D copper(II) sulfate wavelength / nm Absorbance High energy Low energy 791

[Turn over 9 15 Direct-methanol fuel cells make use of methanol as the fuel to generate energy. They are limited in the power they can produce, but can still store high energy content in a small space. The electrolyte in this fuel cell is a dilute aqueous acid. Which of the following statements is incorrect? A Methanol is oxidized in this reaction. B The proton exchange membrane functions as a salt bridge. C The pH at the anode increases temporarily as energy is generated. D Electrons flow from the methanol/carbon dioxide half-cell to that of the oxygen/ water half-cell. 792

10 16 Use of the Data Booklet is relevant to this question. The half-cells for four metals: Mg, X, Y and Z were in turn connected in pairs and the potential difference was recorded. Temperature = 25oC The results obtained are as shown in the table below. Positive electrode Negative electrode e.m.f /V X Mg +2.10 Y Mg +2.72 Mg Z +0.33 Rank the four metals in the order of decreasing reducing power. A Y > X > Mg > Z B X > Y > Mg > Z C Z > Mg > X > Y D Z > Mg > Y > X 17 How many isomers (structural and stereoisomers) are there in C4H9Br? A 2 C 4 B 3 D 5 Metal 1 Metal 2 salt bridge V electron flow 1 mol dm-3 of metal 1 ions 1 mol dm-3 of metal 2 ions 793