SRJC H2 Chem 2012 Prelim P1 QP

1 SERANGOON JUNIOR COLLEGE General Certificate of Education Advanced Level Higher 2 Candidate Name Class CHEMISTRY 9647/01 Preliminary Examination 24 August 2012 Paper 1 Multiple Choice 1 hour Additional Materials: Data Booklet Optical Mark Sheet (OMS) READ THESE INSTRUCTIONS FIRST On the separate multiple choice OMS given, write your name, FIN/NRIC and class in the spaces provided. Shade correctly your class and FIN/NRIC number. Eg. If your NRIC is S9306660Z, shade S9306660Z for the item “index number”. There are forty questions in 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 using a soft pencil on the separate OMS. Each correct answer will score one mark. A mark will not be deducted for a wrong answer. You are advised to fill in the OMS as you go along; no additional time will be given for the transfer of answers once the examination has ended. Any rough working should be done in this question paper. This document consists of 19 printed pages and 1 blank page SRJC PRELIM 9647 P1 Turn Over]

2 SRJC PRELIM 9647 P1 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 To determine the percentage of nitrogen present in a snack, 1.0 g of the snack was boiled with concentrated sulphuric acid to convert all the nitrogen into ammonium sulphate. The ammonium salt obtained was then boiled with excess aqueous sodium hydroxide to liberate the ammonia, which was passed into 25.0 cm 3 of 0.20 mol dm –3 hydrochloric acid. The unreacted hydrochloric acid required 20.0 cm 3 of 0.10 mol dm –3 aqueous sodium hydroxide for complete neutralisation. What is the percentage by mass of nitrogen in the snack? A 2.8% B 4.2% C 7.2% D 8.4% 2 In an experiment, 25 .0 cm3 of 0.2 0 mol dm –3 solution of K 2AO4 reacted exactly with 25.0 cm 3 of 0.10 mol dm –3 a queous sodium sulfate(IV). The half- equation for the oxidation of the sulfate(IV) ion is shown below. SO32– (aq) + H2O (l) ® SO42– (aq) + 2H+ (aq) + 2e– Calculate the final oxidation state of A. A +2 B +3 C +4 D +5 3 Two elements D and E have the following properties. · D and E form ionic compounds Na2D and Na2E respectively. · Element E forms EF6 molecules whereas D is not able to do so. Which pair of electronic configurations for D and E is correct? D E A [He] 2s2 2p2 [Ne] 3s2 3p4 B [He] 2s2 2p2 [Ne] 3s2 3p2 C [He] 2s2 2p4 [Ne] 3s2 3p2 D [He] 2s2 2p4 [Ne] 3s2 3p4

3 SRJC PRELIM 9647 P1 Turn Over] 4 The diagram below shows liquid trichloromethane and liquid benzene flowing from burettes 1 and 2 respectively. What would happen to the flow of the liquids trichloromethane and benzene when a negatively-charged rod is brought near to each of them? Liquid trichloromethane Liquid benzene A Deflected towards the rod Deflected towards the rod B Undeflected Deflected towards the rod C Deflected towards the rod Undeflected D Undeflected Undeflected Burette 1 Liquid trichloromethane Burette 2 Liquid Benzene

4 SRJC PRELIM 9647 P1 Turn Over] 5 The value of pV is plotted against p for two gases, G and H, where p is the pressure and V is the volume of the gas. Which of the following could be the identities of the gases? Gas G Gas H A 0.5 mol of H2 at 25 ºC 0.5 mol of H2 at 50 ºC B 0.5 mol of H2 at 25 ºC 1 mol of SO2 at 25 ºC C 0.5 mol of SO2 at 25 ºC 0.5 mol of SO2 at 50 ºC D 0.5 mol of SO2 at 25 ºC 1 mol of H2 at 25 ºC 6 During an inspection, a small spacecraft of capacity 20 m3 was connected to another of capacity 50 m 3. Before connection, the pressure inside the smaller craft was 40 atm and that inside the larger one was 150 atm. Given that all measurements were made at the same temperature, What is the pressure of the system after the connection? A 78 atm B 95 atm C 119 atm D 190 atm 2x pV p Gas H Gas G 0 x

5 SRJC PRELIM 9647 P1 Turn Over] 7 In which of the following pairs of compounds will compound II have a higher boiling point than compound I? I II A Br Cl B CH3CH2CH2CH2CH3 C(CH3)4 C CH3CH2CH2COOH CH3CH2CH2OH D C CH2Cl C H CH2ClCH3 C C CH2Cl H CH2Cl CH3 8 The conversion of compound X into Z was exothermic and proceeded by two steps , where Y was the intermediate. The steps involved were: Step 1: X ® Y Step 2: Y ® Z It was found that Step 1 is the rate-deter mining step. Which diagram represents the energy level diagram for the reaction?

6 SRJC PRELIM 9647 P1 Turn Over] 9 Pure nitrosyl chloride, NOC l gas, was heated at 320°C in a 2.0 dm 3 vessel. At equilibrium, 30% of the NOCl gas had dissociated according to the equation below and the total pressure was p atm. 2NOCl (g) 2NO (g) + Cl2 (g) What is value of the equilibrium constant, Kp? A 17.9 𝑝𝑝 B 41.7 𝑝𝑝 C 0.0120p D 0.0130p 10 The pH change when 0.10 mol dm –3 CH3COOH is added drop -wise to 10.0 cm 3 of 0.10 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? A B C D Volume of 0.10 mol dm-3 CH3COOH added/ cm3 pH

7 SRJC PRELIM 9647 P1 Turn Over] 11 In an experiment, 70 cm 3 of water at 25ºC was brought to boiling point by burning butane in excess oxygen. Given that the standard enthalpy change of combustion of butane is –2877 kJ mol–1, calculate the volume of butane needed if this process is only 85% efficient. Assume that the specific heat capacity of water is 4.2 J g –1 K–1 and that 1 mole of gas occupies 24 dm3 under the given conditions. A 0.0721 dm3 B 0.156 dm3 C 0.184 dm3 D 0.216 dm3 12 Which of the following changes does not alter the E q value measured for a C l2/Cl– half- cell that is under standard conditions? A Adding water into the half-cell. B Placing the half-cell in an ice bath. C Adding copper(II) ions into the half-cell. D Introducing an inert gas into the half- cell at a pressure of 1 atm through a separate inlet from the Cl2 gas inlet. 13 Which statement concerning the chlorine-containing compounds of elements in the third period, sodium to argon, is correct? A NaCl dissolves easily in water due to favourable ion-dipole interactions and the compound with the highest electrical conductivity in molten state is AlCl3. B PCl3 and C l2O7 are both acidic in nature due to hydration of the compounds in water. C The low boiling points of PC l3 and C l2O7 are due to the weak bond energies involved in the P-Cl bonds and the Cl-O bonds. D The different oxidation states of chlorine in NaC l and Cl2O7 are due to the relative electronegativities of the pairing element and chlorine.

8 SRJC PRELIM 9647 P1 Turn Over] 14 The diagram represents the melting points of four consecutive elem ents in the third period of the Periodic Table. The sketches below represent another two properties of the elements. What are properties J and K? property J property K A third ionisation energy electronegativity B number of valence electrons boiling point C ionic radius nuclear charge D electrical conductivity atomic radius Ÿ Ÿ Ÿ Ÿ proton number 0 melting point / K Ÿ Ÿ Ÿ Ÿ proton number 0 property J Ÿ Ÿ Ÿ Ÿ proton number 0 property K

9 SRJC PRELIM 9647 P1 Turn Over] 15 Which of the following is true about the thermal decomposition of magnesium nitrate? A Sodium nitrate is thermally unstable as compared to magnesium nitrate. B Ev