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

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