2019 TMJC H2 Chem Prelim P1 QP

Tampines Meridian Junior College 2019 JC2 Prelim H2 Chemistry _________________________________________________________________________________ H2 CHEMISTRY 9729/01 Paper 1 Multiple Choice 26 September 2019 1 hour Additional Materials: Multiple Choice Answer Sheet Data Booklet READ THESE INSTRUCTIONS FIRST Write in soft pencil. Do not use staples, paper clips, glue or correction fluid. Write your name, class and index number on the Answer Sheet in the spaces provided unless this has been done for you. There are thirty 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. 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 document consists of 18 printed pages. TAMPINES MERIDIAN JUNIOR COLLEGE JC2 PRELIMINARY EXAMINATION

2 Tampines Meridian Junior College 2019 JC2 Prelim H2 Chemistry 1 Some data of the ions of four unknown elements are given in the table below. A+ B– D2– E3– mass number 21 20 20 21 number of protons – 11 9 – number of electrons 9 – – 12 Which of the following correctly shows pairs of isotopic and isoelectronic species? isotopic isoelectronic A D2–, E3– B–, E3– B B–, D2– A+, B– C B–, D2– B–, E3– D D2–, E3– A+, B– 2 The first six ionisation energies of element G are plotted in the graph below. number of electrons removed Which of the following can be deduced from the graph? A There are 2 quantum shells in element G. B Element G is from Group 2 in the Periodic Table. C The fifth and sixth electrons are removed from the same subshell. D The identity of element G is carbon. log10 (ionisation energy)

3 Tampines Meridian Junior College 2019 JC2 Prelim H2 Chemistry 3 For which of the following pairs does the first molecule have a higher polarity than the second molecule? 1 CH3OH, CH3I 2 CF4, CCl4 3 cis-CHF=CHF, trans-CHF=CHF A 1 only B 1 and 3 C 2 and 3 D 1, 2 and 3 4 Three substances H, I and J have physical properties shown in the table below. substance melting point/ °C boiling point/ °C electrical conductivity of solid of liquid H 801 1413 poor good I 2852 3600 poor good J 3500 at very high pressure unable to determine poor unable to determine What are the possible identities for substances H, I and J? H I J A NaCl AlCl3 C (diamond) B MgO AlCl3 C (graphite) C NaCl MgO C (graphite) D NaCl MgO C (diamond)

4 Tampines Meridian Junior College 2019 JC2 Prelim H2 Chemistry 5 Which of the following diagrams correctly describe the behaviour of a fixed mass of an ideal gas at constant temperature? [c is concentration] graph 1 graph 2 graph 3 A 2 only B 1 and 2 C 2 and 3 D 1, 2 and 3 6 In which of the following reactions is the underlined reactant acting as a Lewis acid? A BF3 + F  BF4 B AlCl3 + Cl2  AlCl4 + Cl+ C Ag+ + 2NH3  [Ag(NH3)2]+ D H2O + HSO3  H2SO3 + OH 7 Which of the following statements is true of the Period 3 chlorides, NaCl to PCl5? A The melting points of the chlorides show a continuously decreasing trend. B The pH of the solutions formed when the chlorides are added to water range from alkaline to acidic. C Three of the chlorides have simple molecular structures. D The only chlorides which undergo hydrolysis in water are AlCl3 and MgCl2. V pV c p p c p

5 Tampines Meridian Junior College 2019 JC2 Prelim H2 Chemistry 8 The relative abundances of the isotopes of a sample of titanium are shown in the table below. Given that the relative atomic mass of the sample is 47.862, what is the value of z? A 214.2 B 79.1 C 78.7 D 26.6 9 A metallic salt was found to react exactly with sulfite ions in a 2 : 1 ratio. In this reaction, the sulfite ion is oxidised as follows. SO32(aq) + H2O(l)  SO42(aq) + 2H+(aq) + 2e– What is the new oxidation number of the metal in the salt if its original oxidation number was +3? A +1 B +2 C +4 D +5 10 The enthalpy changes for the following reactions are given: 2Cr(s) + 3 2 O2(g) → Cr2O3(s) Hf (Cr2O3(s))= 1120 kJ mol1 C(s) + 1 2 O2(g) → CO(g) Hf (CO(g))= 110 kJ mol1 What is the enthalpy change of reaction for the following reaction, in terms of kJ mol1? 3C(s) + Cr2O3(s) → 2Cr(s) + 3CO(g) A  940 B  870 C + 590 D + 790 relative isotopic mass 46 47 48 relative abundance 11.2 10.1 z

6 Tampines Meridian Junior College 2019 JC2 Prelim H2 Chemistry 11 An experiment was conducted by reacting propyne with hydrogen gas in a shock tube. CH3C≡CH(g) + 2H2(g) → CH3CH2CH3(g) The value of G for the reaction is found to be negative at low temperature. What is the sign of H and S for the above reaction? H S A   B +  C  + D + + 12 The kinetics of the reaction between hydrogen peroxide and acidified iodide ions were investigated. H2O2(aq) + 2H+(aq) + 2I(aq) → I2(aq) + 2H2O(l) The rate equation was found to be: rate = k[H2O2][I] Which of the following shows the correct labelling of the x-axis for Graph I and y-axis for Graph II? Graph I Graph II rate of reaction y x time x-axis for Graph I y-axis for Graph II A [I] [H2O2][I] B [H+] [I2] C [H2O2][I–] [H+] D [H2O2][H+] [I]

7 Tampines Meridian Junior College 2019 JC2 Prelim H2 Chemistry 13 The reaction between HBr and O2 is thought to occur via a multi-step mechanism: HBr + O2 → HO2Br (slow) HO2Br + HBr → 2HOBr (fast) HOBr + HBr → Br2 + H2O (fast) The overall reaction is given to be 4HBr + O2 → 2Br2 + 2H2O. Which of the following statements are true? 1 The overall order of reaction is 2. 2 HO2Br is the only intermediate in the reaction. 3 HOBr acts as a catalyst in the reaction. A 1 only B 3 only C 1 and 2 D 1, 2 and 3 14 L and M can react together to reach equilibrium in the reaction below. L(g) + M(g) Q(g) + R(g) In an experiment, 1.0 mole each of L and M were reacted at constant pressure P and temperature 350 ºC. The amount of R present in the mixture at intervals of time was recorded. The experiment was repeated at the same pressure P, but at a temperature of 700 ºC. The results for both experiments are shown below. Which one of the following information cannot be deduced from the graph? A The value of Kc decreases with an increase in temperature. B The equilibrium is achieved at a faster rate at higher temperatures. C The enthalpy change for the forward reaction is negative. D The activation energy of the forward reaction is high. Number of moles of R time

8 Tampines Meridian Junior College 2019 JC2 Prelim H2 Chemistry 15 The dissociation constants, Kw, for the ionisation of water at different temperatures are given below. H2O(l) H+(aq) + OH(aq) temperature / °C Kw / mol2 dm–6 0 1.15 x 10–15 25 1.00 x 10–14 50 5.50 x 10–14 What can be deduced from this information? A Only at 25 °C are [H+] and [OH–] equal. B Kw is not affected by changes in temperature. C The forward reaction is exothermic. D The pH of water decreases as temperature increases. 16 The following tests were performed on an aqueous solution containing chloride and iodide ions. step test observations 1 Add excess AgNO3(aq). Mixture of white and yellow precipitates is formed. 2 To the mixture from step 1, add excess NH3(aq). White precipitate dissolves