2019 DHS Prelim H2 Chem P1 QP

This question paper consists of 16 printed pages and no blank pages. © DHS 2019 [Turn over Name: Index Number: Class: DUNMAN HIGH SCHOOL Preliminary Examination 2019 Year 6 H2 CHEMISTRY 9729/01 Paper 1 Multiple Choice 30 September 2019 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 2019 9729/01 [Turn Over 1 Sodium azide, NaN 3, and potassium nitrate, KNO 3, are both present in the airbags of some cars. When the airbag is activated, sodium azide first decomposes to give sodium and nitrogen. 2NaN3(s) → 2Na(s) + 3N2(g) The sodium then reacts with potassium nitrate to produce more nitrogen. 10Na(s) + 2KNO3(s) → K2O(s) + 5Na2O(s) + N2(g) The nitrogen produced in these two reactions inflates the airbag. 2.00 mol of gas is needed to inflate the airbag. What is the amount of sodium azide needed to inflate the airbag? A 0.625 mol B 1.00 mol C 1.25 mol D 1.33 mol 2 Use of the Data Booklet is relevant to this question. Sodium percarbonate, (Na2CO3)x•y(H2O2) is an oxidising agent in some home and laundry cleaning products. 10.0 cm3 of 0.100 mol dm–3 sodium percarbonate releases 48.0 cm3 of carbon dioxide at room conditions on acidification. An identical sample reacts with 24.0 cm3 of 0.0500 mol dm–3 KMnO4 before the first pink colour appears. Given that 5H2O2 ≡ 2KMnO4, what is the ratio of 𝑦 𝑥? A 1 3 B 2 3 C 3 2 D 3 1

3 © DHS 2019 9729/01 [Turn Over 3 Use of the Data Booklet is relevant to this question. A compound is made up from two elements, Y and Z. Each separate atom of Y and of Z in their ground states has exactly 2 unpaired electrons. What could the compound be? 1 TiCl4 2 SiO2 3 NiS A 1, 2 and 3 B 2 and 3 only C 1 and 3 only D 2 only 4 Which graph correctly describes the behaviour of fixed masses of the ideal gases I and J, where I has a higher Mr than J? A B C D Constant T I J pV p Constant T J I pV p T V Constant p J I T V Constant p I J

4 © DHS 2019 9729/01 [Turn Over 5 Which feature is present in the carbonate, ethanoate, nitrate and phenoxide ions? A All bond angles are 120 B Dative covalent bonds C Delocalised electrons D Hydrogen bonds 6 When an equilibrium is established in a reversible reaction, the standard Gibbs free energy, G, is related to the equilibrium constant, Kc, by the following equation. G = – RT ln Kc where R is the gas constant and T is the temperature in Kelvin. Which of the following statement is correct? 1 At constant temperature, a shift in position of equilibrium to the right results in the same value of G. 2 The forward reaction is spontaneous for all values of Kc. 3 Adding a catalyst makes G more negative. A 1, 2 and 3 only B 2 and 3 only C 1 and 3 only D 1 only 7 Three equilibrium reactions are shown below. All three reactions have an equilibrium constant, Kc, that is greater than one. N2H5+ + NH3 NH4+ + N2H4 NH3 + HBr NH4+ + Br– N2H4 + HBr N2H5+ + Br– Assuming that all solutions have the same concentration, which correctly list s the three solutions in order of decreasing pH? A HBr > N2H5+ > NH4+ B N2H5+ > NH4+ > HBr C NH4+ > N2H5+ > HBr D N2H5+ > HBr > NH4+

5 © DHS 2019 9729/01 [Turn Over 8 Which of the following resultant solutions will have the lowest pH? A 15 cm3 of 0.100 mol dm–3 KOH added to 15 cm3 of 0.050 mol dm–3 benzoic acid B 50 cm3 of 0.050 mol dm–3 KOH added to 25 cm3 of 0.100 mol dm–3 benzoic acid C 25 cm3 of 0.100 mol dm–3 KOH added to 50 cm3 of 0.100 mol dm–3 benzoic acid D 5 cm3 of 0.100 mol dm–3 KOH added to 50 cm3 of 0.100 mol dm–3 benzoic acid 9 The graph below shows how the solubility of two salts, KC lO3 and KC l, varies with temperature. 10 g of KClO3 and 50 g of KCl was added to 100 g of water at 90 C. Which statement is correct as the mixture is cooled to 10 C? 1 The first trace of precipitate occurs at about 76 C. 2 The aqueous solution is saturated with KClO3 and KCl at 10 C. 3 The maximum mass of KCl that can be precipitated without any trace of solid KClO3 is approximately 13 g. A 1, 2 and 3 B 2 and 3 only C 1 and 2 only D 3 only

6 © DHS 2019 9729/01 [Turn Over 10 Hydrazine, N 2H4, used in rocket fuels can be obtained by the reaction of ammonia and hydrogen peroxide according to the following equation. 2NH3(g) + H2O2(l) → N2H4(l) + 2H2O(l) Hreaction = 241 kJ mol1 Using the value of Hreaction given above and the data below, calculate the H (in kJ mol1) for decomposition of hydrazine into N2(g) and H2(g). compound Hf / kJ mol1 NH3(g) 46 H2O2(l) 188 H2O(l) 286 A +189 B +51 C 189 D 51 11 Methanol can be synthesised from carbon monoxide and hydrogen according to the equation CO(g) + 2H2(g) CH3OH(g) Higher yield of methanol can be achieved at a lower temperature. Which graph corresponds to the forward process? A B C D G / kJ mol–1 T / K 0 G / kJ mol–1 T / K 0 G / kJ mol–1 T / K 0 G / kJ mol–1 T / K 0

7 © DHS 2019 9729/01 [Turn Over 12 The table below shows the results of three experiments conducted for the following reaction. P + Q  products experiment [P] / mol dm–3 [Q] / mol dm–3 rate / mol dm–3 s–1 1 0.012 0.005 1.0 x 10–4 2 0.024 0.010 2.0 x 10–4 3 0.048 0.010 4.0 x 10–4 Another three experiments were carried out at different temperatures and the results obtained are shown below. experiment [P] / mol dm–3 [Q] / mol dm–3 temperature / oC 4 0.10 0.20 40 5 0.20 0.20 30 6 0.30 0.30 20 If the rate constant doubles for each 10 oC rise in temperatu re, which statements regarding experiments 4 to 6 are correct? 1 rate of reaction of experiments 4 and 5 are the same. 2 rate of reaction of experiment 4 is two times faster than experiment 6. 3 rate of reaction of experiment 6 is the slowest. A 1, 2 and 3 B 1 and 2 only C 1 and 3 only D 2 and 3 only

8 © DHS 2019 9729/01 [Turn Over 13 X, Y and Z are elements in Period 3 of the Periodic Table. The results of some experiments carried out with compounds of these elements are shown. X Y Z result of reacting the oxide of the element with HCl(aq) salt solution salt solution mixture of acids result of adding the oxide of the element to H2O(l) no reaction alkaline solution acid solution result of adding the chloride of the element to H2O(l) hydrolyses dissolves hydrolyses What could be the identities of X, Y and Z? X Y Z A Al P S B Al Na P C Si Mg P D Si Na Al 14 The table shows the results of experiments in which the halogens, K2, L2 and M2 were added to separate aqu