DHS Prelim P1 QP with answer key

This question paper consists of 15 printed pages and 1 blank page. © DHS 2018 [Turn ov er Name: Index Number: Class: DUNMAN HIGH SCHOOL Preliminary Examination 2018 Year 6 H2 CHEMISTRY 9729/01 Paper 1 Multiple Choice 24 September 2018 1 hour Additional Materials: Data Booklet Optical Mark Sheet INSTRUCTIONS TO CANDIDATES 1 Write your name, index number and class on this question paper and the OTAS Mark Sheet. 2 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 Optical Mark Sheet. 3 Each correct answer will score one mark. A mark will not be deducted for wrong answer. 4 Any rough working should be done in this booklet. 5 The use of an approved scientific calculator is expected, where appropriate. 6 On the OTAS Mark Sheet, please shade the code as “Class/Index number”. For illustration only: A student from class 6C38, with index number 02, should shade “3802”. 3 8 0 2

2 © DHS 2018 9729/01 1 Which option contains one mole of the stated particles? [D = H1 2 ] A carbonate ions in 60 g of sodium carbonate B neutrons in 1.8 g of heavy water, D2O C electrons in 0.1 mol of OH– ions D oxygen atoms in 11.35 dm3 of O3, under s.t.p. 2 NF3 can be obtained from the reaction between ammonia and fluorine gas. 4NH3 + 3F2 → NF3 + 3NH4F Which statement about the reaction is correct? A NH 3 undergoes disproportionation. B The oxidation number of nitrogen in NF3 is +3. C NH3 is a stronger oxidising agent than F2. D One mole of F2 loses two moles of electrons. 3 Use of the Data Booklet is relevant to this question. Which statement regarding 26Mg2+ and 27Al3+ ions is true? 1 26Mg2+ has more protons than 27Al3+. 2 Both ions have more neutrons than protons in their nuclei. 3 Both ions have outer electronic configuration 2s 22p6. 4 Both ions have the same number of neutrons. A 1 and 2 only B 1 and 3 only C 3 and 4 only D 2, 3 and 4 only

3 © DHS 2018 9729/01 [Turn Over 4 Two ideal gases X and Y were placed separately into two bulbs of the same volume and pressure. The density of gas X is three times that of gas Y and the molecular mass of gas X is twice that of gas Y. What is the ratio of the temperature (in Kelvin) of gas X to that of gas Y in the two separate bulbs? A 1 : 3 B 1 : 6 C 2 : 3 D 3 : 2 5 A compound has the structure shown. C H H H C O O H x y z What are the values of the bond angles x, y and z? x y z A 90° 109.5 ° 104.5 ° B 90° 120 ° 180° C 109.5° 109.5 ° 180 ° D 109.5° 120 ° 104.5 °

4 © DHS 2018 9729/01 6 Use of the Data Booklet is relevant to this question. Which graph shows the correct trend when the melting point of the oxide of each of the elements Mg, Al, Si and P is plotted against its ionic radius? A Melting point of oxide Ionic radius of element . Al Mg. . . Si P B Melting point of oxide Ionic radius of element .Al Mg. . . Si P C Ionic radius of element . Al Mg . . . Si P Melting point of oxide D Ionic radius of element . Al Mg. . . Si P Melting point of oxide

5 © DHS 2018 9729/01 [Turn Over 7 The graph represents the change in mass that occurs when 1.0 g of powdered magnesium carbonate, MgCO3, is heated at a temperature, T. Which graph would be obtained by heating 1.0 g of powdered calcium carbonate, CaCO 3, at the same temperature, T? A B C D Time / min Mass / g 1.0 − 0.5 − − 0 | | | | | Time / min Mass / g 1.0 − 0.5 − − 0 | | | | | Time / min Mass / g 1.0 − 0.5 − − 0 | | | | | Time / min Mass / g 1.0 − 0.5 − − 0 | | | | | Time / min Mass / g 1.0 − 0.5 − − 0 | | | | |

6 © DHS 2018 9729/01 8 X2, Y2 and Z2 are Cl2, Br2 and I2 but are not necessarily in the given order. The table below recorded observations when these halogens are separately added to aqueous solutions containing the halide ions followed by the addition of an organic solvent, CCl4. Experiment Reactants Observation after shaking with CCl4 1 X2 (aq) + Y– (aq) Violet organic layer seen. 2 Y2 (aq) + X– (aq) (Observations not recorded) 3 Z2 (aq) + X– (aq) Orange-red organic layer seen. 4 Z2 (aq) + Y– (aq) Violet organic layer seen. Which statement could be deduced from the above experiments, given X2 (aq) is an orange solution? A The colour of the organic layer in Experiments 2 and 4 is the same. B Identity of Z2 is Br2. C There is no redox reaction occurring in Experiment 3. D X2 is a stronger oxidising agent than Z2. 9 For which process is the enthalpy change always negative? A Dissolving an ionic solid in water. B Reaction between an acid and a base. C Forming gaseous atoms from a diatomic molecule. D Synthesising a compound from its elements. 10 A rock sample was found to contain isotopes T and U which are radioactive. Initially, the ratio of the number of atoms of T to U in the rock sample is 1 : 16. The decay of isotopes T and U was found to follow first order kinetics. The half–life of T is 12 days while that of U is 3 days. How long, in days, will it take for a rock sample to contain a molar ratio of T to U of 4 : 1? A 6 B 12 C 18 D 24

7 © DHS 2018 9729/01 [Turn Over 11 The stoichiometry of a reaction is shown by the equation below. L(g) + M(g) ⇌ Q(g) + R(g) ∆H = –20 kJ mol–1 Two experiments were carried out in enclosed vessels which the rate of production of R was measured. The results are shown in the diagram below. 0 No of moles of R Time Experiment 1 Experiment 2 Which changes in the conditions might explain the results shown? 1 Temperature of the vessel is higher in Experiment 2. 2 A smaller vessel is used in Experiment 2. 3 A catalyst is used in Experiment 2. A 1, 2 and 3 B 1 and 2 only C 2 and 3 only D 1 only 12 In which reaction is the first reactant not acting as a Bronsted-Lowry base? A NH3 + CH3Cl → CH3NH3+ + Cl– B OH– + HSO4– → H2O + SO42– C CH3OH + HClO4 → CH3OH2+ + ClO4– D HNO3 + H2SO4 → H2NO3+ + HSO4–

8 © DHS 2018 9729/01 13 The solubility products of calcium fluoride and calcium carbonate are 4.0 × 10–11 mol3 dm–9 and 8.7 × 10–9 mol2 dm–6 at 25 °C respectively. Which statement is correct? 1 When calcium nitrate is added into a 1 dm 3 solution containing 0.01 mol of fluoride and 0.01 mol of carbonate ions in order to separate fluoride and carbonate ions, calcium fluoride is collected as the filtrate upon filtration. 2 Calcium fluoride has a lower molar solubility than calcium carbonate. 3 Addition of sodium fluoride to a saturated solution containing calcium fluoride does not change the solubility product of calcium fluoride. A 1, 2 and 3 only B 2 and 3 only C 1 and 3 only D 3 only 14 A concentration cell set up is shown below. The net effect of a concentration cell is the same as mixing the two solutions of different concentrations until concentration equilibrium is established. V Ag 0.5 mol dm−3 AgNO3(aq) M N Ag 1.0 mol dm−3 AgNO3(aq) salt bridge Which statement is true? A The E cell value decreases when s