NJC Prelim P1 QP

NJC Preliminary Examination 9729/01/18 [Turn Over NATIONAL JUNIOR COLLEGE SH2 PRELIMINARY EXAMINATION Higher 2 CANDIDATE NAME SUBJECT CLASS REGISTRATION NUMBER CHEMISTRY Paper 1 Multiple Choice Additional Materials: Optical Answer Sheet Data Booklet 9729/01 Thur 13 September 2018 1 hour READ THESE INSTRUCTIONS FIRST Write in soft pencil. Do not use staples, paper clips, glue or correction fluid. Write your name, subject class and registration number on the Answer Sheet in the spaces provided unless this has been done for you. 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 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. The use of an approved scientific calculator is expected, where appropriate. This paper consists of 17 printed pages

2 NJC Preliminary Examination 9729/01/18 [Turn Over Instructions on how to fill in the Optical Mark Sheet Student Examples of Registration No. Shade: 1705648 75648 Example: Shade the index number in a 5 digit format on the optical mark sheet: 2nd digit and the last 4 digits of the Registration Number. SH1 CT CM G or IP B

3 NJC Preliminary Examination 9729/01/18 [Turn Over + – R S T For each question there are four possible answers, A, B, C, and D. Choose the one you consider to be correct. 1 Use of the Data Booklet is relevant to this question. The following are flight paths of charged particles when accelerated in an electric field. Which correctly identifies S, T and U? S T U A 15O+ 14C+ 14N+ B 15O⎯ 15O+ 28Si+ C 14N⎯ 28Si2+ 14C2+ D 14N⎯ 14C+ 28Si2+ 3 In which row are the molecules arranged in order of increasing bond angle? 1 CH 4, AlCl3, XeF2 2 H2S, PH3, NH3, 3 NF3 , NCl3, SO3 A 1, 2 and 3 B 1 and 2 C 2 and 3 D 1 only 2 In which sequence is the molecules listed in the order of increasing dipole moment? A SO3, CO2, AlCl3 B H2O, H2S, HBr C CF4, CO, HF D NH3, HF, BeCl2 S T U

4 NJC Preliminary Examination 9729/01/18 [Turn Over 4 Propadiene and propyne both have the same molecular formula, C 3H4. They exist in equilibrium as shown: H2C=C=CH2 CH 3C≡CH propadiene propyne Which bond is present in propadiene but not present in propyne? A a σ bond formed by s – sp overlap B a π bond formed by p – p overlap C a σ bond formed by sp – sp2 overlap D a σ bond formed by sp2 – sp2 overlap 5 Use of the Data Booklet is relevant to this question. A reaction scheme regarding manganese compounds is shown below. Which statements are true? 1 Off-white solid S is able to dissolve in excess of NH3(aq). 2 Manganese in brown solid P has an oxidation state of +4. 3 Reagent Q can be acidified [V(H2O)6]3+(aq). 4 Off white solid S turns brown upon standing. A 1, 2 and 4 B 2, 3 and 4 C 2 and 3 D All correct KMnO4(aq) Fe(OH)2 brown solid P reagent Q [Mn(H2O)6]2+(aq) NaOH(aq) off-white solid S NH3(aq) off-white solid S

5 NJC Preliminary Examination 9729/01/18 [Turn Over 6 In which chemical reaction does the transition metal compound or element behave as the described catalyst? Reaction Catalyst 1 Formation of ethanal from ethanol, using acidified potassium dichromate Homogeneous 2 Formation of oxygen from hydrogen peroxide, using iron(III) hydroxide Heterogeneous 3 Chlorination of benzene, using chlorine and iron(III) chloride Homogeneous 4 Removal of air pollutants in exhaust systems of cars, using nickel Heterogeneous A 1, 2 and 4 B 2 and 3 C 3 and 4 D 2, 3 and 4 7 Use of the Data Booklet is relevant to this question. Given the following standard enthalpy changes, ∆H /kJ mol−1 C(graphite) + 2H2(g) → CH4(g) −75 What is the standard enthalpy change of atomisation of graphite? A +693 kJ mol−1 B +1129 kJ mol−1 C −2151 kJ mol−1 D −2587 kJ mol−1 8 Ammonia gas and hydrogen chloride gas react to form ammonium chloride as shown in the equation below: NH3(g) + HCl(g) → NH4Cl(s) ∆H o= −176 kJ mol−1 The magnitude of standard entropy change of this reaction is 284 J K−1 mol−1. Which statements are correct? 1 ∆Go = −261 kJ mol−1. 2 The reaction becomes non-spontaneous at temperatures higher than 620 K. 3 There is an increase in order as strong hydrogen bonding between NH3 and HCl hold the particles in NH4Cl in fixed positions and close to each other. A 1 only B 1 and 2 C 2 only D 2 and 3

6 NJC Preliminary Examination 9729/01/18 [Turn Over 9 The graph below shows how the fraction of X, which represents one of the following compounds in the given equilibrium mixture, varies with temperature at pressures of Y Pa and Z Pa. 4NH3(g) + 3O2(g) 2N 2(g) + 6H2O(g) ΔH = −1267 kJ mol−1 Identify X and the correct relative magnitudes of Y and Z. X Pressure A N2 Z > Y B O2 Y > Z C H2O Y > Z D NH3 Z > Y 10 One of the key production stages in the Contact Process is the production of sulfur trioxide. 2SO2(g) + O2(g) 2SO 3(g) ∆H < 0 The rate constants of the forward and backward reactions are given as k 1 and k−1 respectively. What happens to k 1, k−1 and Kc if the temperature of the reaction is increased? k1 k−1 Kc A increase increase increase B increase decrease increase C decrease increase decrease D increase increase decrease Fraction of X in equilibrium mixture Temperature Y Pa Z Pa

7 NJC Preliminary Examination 9729/01/18 [Turn Over 11 The reaction between carbon monoxide and chlorine was studied in an experiment by mixing the two gases and changing the reaction conditions inside the reaction vessel at different times during the experiment. The concentrations of the gases in the vessel were followed with time, and the following graph is obtained. CO(g) + Cl 2(g) COC l2(g) ΔHo = –113.4 kJ mol–1 Which conclusion deduced from the graph is incorrect? A The rate of forward reaction equals the rate of backward reaction at 7 min. B The change in concentration from 7.5 min to 10 min was produced by an increase in volume at constant temperature. C The equilibrium constant, Kc, for the system when determined at 7 min is 0.417 mol–1 dm3. D The change in concentration from 10 min to 15 min was produced by the addition of more chlorine. 0 0.1 0.2 0.3 0.4 0.5 0.6 0.9 1.0 0.7 concentration / mol dm–3 time / min 0.8 5 10 15 7.5 CO(g) Cl2(g) COCl2(g)

8 NJC Preliminary Examination 9729/01/18 [Turn Over 12 Substances X, Y and Z react according to the following equation: X(aq) + 2Y(aq) + Z(aq)  2W(aq) + U(aq) To find the rate equation for the above reaction, two sets of separate experiments were performed, in which the initial concentrations of each of the r