TJC 08 TJC Chem H2 Prelim P1

TEMASEK JUNIOR COLLEGE CHEMISTRY 9746/01 Paper 1 Multiple Choice Friday 19th SEPTEMBER 2008 1 hour Additional materials: Data Booklet Multiple Choice Answer Sheet READ THESE INSTRUCTIONS FIRST Do not open this 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, index number and CG on the Answer Sheet in the spaces provided. There are forty questions on this paper. Answer all questions. For each question, there are four possible answers labelled 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. You may use a calculator. This document consists of 18 printed pages. [Turn over

2 TJC H2 Chemistry Paper 1 2008 [Turn over Section A For each question there are four possible answers, A, B, C and D. Choose the one you consider to be correct. 1 Ethanonitrile, CH3CN was boiled with NaOH and the NH 3 gas evolved was passed into 50 cm3 of 1.00 mol dm -3 of HC l. The excess acid required 26.00 cm 3 of 1.00 mol dm -3 NaOH solution for neutralization. What was the mass of ethanonitrile used? (Mr of CH3CN = 41) A 0.492 g B 0.984 g C 1.07 g D 1.97 g 2 In which of the following pairs does the first species have a larger bond angle than the second? A ClO3 -, BrO3 - B SO3 2-, SO4 2- C PCl3, AlCl3 D H2O, H3O+ 3 Antimony, Sb, is in Group V of the Periodic Table. It forms salts which contain the SbF 5 n- anion, the shape of which is square pyramidal. What is the value of n? A 2 B 3 C 4 D 5

3 TJC H2 Chemistry Paper 1 2008 [Turn over 4 Which of the following compounds is the least volatile? A CH3CH2CH2CH2OH B (CH3)3COH C CH3CH2CH2CH2NH2 D (CH3)3CNH2 5 Each of the following equilibria is subjected to two changes carried out separately: (i) the volume of vessel is increased at constant temperature; (ii) the temperature is increased at constant pressure. For which equilibrium will both of these changes result in an increase in the proportion of products? A H2(g) + I2(g) 2H I(g) ∆H = +53 kJ mol-1 B 4NH3(g) + 5O2(g) 4NO(g) + 6H 2O(g) ∆H = -950 kJ mol-1 C N2O4(g) 2NO 2( g ) ∆H = +57 kJ mol-1 D N2(g) + 3H2(g) 2NH 3(g) ∆H = -92 kJ mol-1 6 What is the pH value of 0.05 mol dm -3 of ammonium chloride solution, given the Kb of NH3 is 1.8 x 10-5 mol dm-3? A 3.02 B 5.28 C 8.72 D 10.98

4 TJC H2 Chemistry Paper 1 2008 [Turn over 7 Which set of solutions below will not give a buffer solution when they are mixed? A 50 cm3 of 0.10 mol dm-3 CH3CO2H and 50 cm3 of 0.10 mol dm-3 CH3CO2Na B 100 cm3 of 0.10 mol dm-3 CH3CO2H and 50 cm3 of 0.10 mol dm-3 NaOH C 50 cm3 of 0.10 mol dm-3 CH3CO2Na and 100 cm3 of 0.10 mol dm-3 HCl D 100 cm3 of 0.10 mol dm-3 CH3CO2Na and 50 cm3 of 0.10 mol dm-3 HCl 8 Which of the following is true of the identity of Gas J? A Nitrogen gas at a higher temperature B Neon gas at 298 K C Hydrogen gas at 298 K D Carbon dioxide at 298 K PV RT Gas J Nitrogen gas at 298 K 1.0 P / atm

5 TJC H2 Chemistry Paper 1 2008 [Turn over 9 Nitrosyl fluoride, NOF can be produced from nitrogen monoxide and fluorine. 2NO(g) + F2(g) Æ 2NOF(g) The rate equation for this reaction is rate = k[NO][F2]. What can be deduced from the information given? A The reaction involves a three step mechanism. B Position of equilibrium will shift to the right on increasing pressure. C Half-life with respect to fluorine gas is equal to . D One molecule of NO reacts with one molecule of F2 in the slow step. 10 Which of the following graphs is correct of the following reaction, when N is in excess? L + M + N Æ P + Q The rate equation for this reaction is rate = k[M][N] A C B D ln2 k rate [M] rate [L] [N] [M] Time Time 00 0 0

6 TJC H2 Chemistry Paper 1 2008 [Turn over 11 Which of the following statements is true about the energy profile above? A R is the intermediate formed. B The enthalpy change of the reaction is E3 – E2. C The reaction is catalysed by a heterogenous catalyst. D E2 corresponds to the activation energy for the reaction in the second step. 12 Electrolysis of aqueous hydrochloric acid results in gases produced at both the anode and cathode. What is the current required to produce 70 cm 3 of gas at the anode in 15 min at room temperature and pressure? A 0.625 A B 1.25 A C 6.25 A D 21.4 A R Energy Extent of reaction E2 E3 E1

7 TJC H2 Chemistry Paper 1 2008 [Turn over 13 When 0.15 g of magnesium was added to an excess of dilute sulphuric acid in a calorimeter (with negligible heat capacity), a maximum temperature rise of 6.2 oC was recorded. What is the enthalpy change for the reaction? (heat capacity of acid = 494 J K-1) A - 3.06 kJ mol-1 B - 496 kJ mol-1 C - 632 kJ mol-1 D - 744 kJ mol-1 14 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 First I.E / kJ mol -1 Atomic Radius / nm Na Mg Al Si P S Cl Na Mg Al Si P S Cl Na Mg Al Si P S Cl Melting Point / °C Na Mg Al Si P S Cl Electrical Conductivity

8 TJC H2 Chemistry Paper 1 2008 [Turn over 15 Cu2SO4 and anhydrous CuSO4 are both white while CuSO4.5H2O is blue. Which of the following statements best explains the above observation? A Copper in all three compounds has partially filled 3d orbitals. B Copper in Cu 2SO4 has a fully filled 3d orbital while copper in anhydrous CuSO 4 and CuSO4.5H2O has partially filled 3d orbitals. C Copper in CuSO4.5H2O has partially filled 3d orbitals. D Electrons in the 3d orbitals of copper in CuSO 4.5H2O can undergo transitions from a 3d orbital of lower energy to another 3d orbital of higher energy. 16 S is a transition element. The 3d sub-shell of S in the compound K[S(C2O4)2(NH3)2] contains 3 electrons. How many unpaired electrons does S contain when it is in the elemental state? A 3 B 4 C 5 D 6 17 3 moles of chlorine gas was passed into a small sealed container containing an unknown mixture. After complete reaction, it was found that after adding silver nitrate till in excess, 5 moles of silver chloride precipitate was obtained. What substance(s) could the unknown mixture contain? A Concentrated sulphuric acid B Concentrated sulphuric acid and manganese( IV) oxide C Dilute sodium hydroxide at 15 oC D Dilute sodium hydroxide at 70 oC

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