YJC H1 CHEM P1

This question paper consists of 14 printed pages. YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISH UN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE CANDIDATE’S NAME: ______________________________ CTG: _________________ YISHUN JUNIOR COLLEGE JC2 PRELIMINARY EXAMINATION 2015 CHEMISTRY 8872/01 HIGHER 1 27 August 2015 Paper 1: Multiple-Choice Questions 1400 hrs – 1450 hrs 50 minutes Additional materials: Optical Mark Sheet Data Booklet INSTRUCTIONS TO CANDIDATES Section A & B: Multiple Choice Questions Write in soft pencil. Do not use paper clips, highlighters, glue or correction fluid. Write your name and CTG on the Answer Sheet. Shade your NRIC number in the spaces provided in the Optical Mark Sheet. There are t hirty 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.

2 8872 / YJC / 2015 / Preliminary Examination / Paper 1 Section A For each question there are four possible answers, A, B, C, and D. Choose the one you consider to be correct. 1 Naturally occurring neon is a mixture of three isotopes, 20Ne, 21Ne and 22Ne. The relative atomic mass of neon is 20.18. What could be the relative abundance for each of the three isotopes? A 90.92% 20Ne, 0.26% 21Ne and 8.82% 22Ne B 91.1% 20Ne, 7.9% 21Ne and 1.0% 22Ne C 95.0% 20Ne, 3.2% 21Ne and 1.8% 22Ne D 96.3% 20Ne, 0.3% 21Ne and 3.4% 22Ne 2 Carbon disulfide, CS2, is a volatile flammable liquid used in the manufacture of cellophane. Carbon disulfide vapour burns in oxygen according to the following equation. CS2(g) + 3O2(g)  CO2(g) + 2SO2(g) A sample of 10 cm 3 of carbon disulfide vapour was burned in 40 cm 3 of excess oxygen. After measuring the volume of gas es after burning, the product gases were treated with an excess of aqueous sodium hydroxide and the volume of gases was measured again. What were the measured volumes? Volume of gas after burning / cm3 Volume of gas after adding NaOH / cm3 A 30 0 B 30 20 C 40 10 D 40 20

3 8872 / YJC / 2015 / Preliminary Examination / Paper 1 3 A disproportionation reaction is a reaction in which an element in a species undergoes both oxidation and reduction simultaneously. Which of the following is not a disproportionation reaction? A 3ClO─  2Cl─ + ClO3 ─ B 2FeSO4  Fe2O3 + SO2 + SO3 C H2O + 2NO2  HNO2 + HNO3 D H2C2O4  H2O + CO + CO2 4 The table below contains incomplete information about the three isoelectronic ions X, Y and Z. The atoms of Y and Z are isotopes. ion mass number atomic number number of neutrons number of electrons charge X 55 25 b Y 56 26 Z a 31 +3 What are the possible values of a and b? a b A 56 +2 B 56 +3 C 57 +2 D 57 +3

4 8872 / YJC / 2015 / Preliminary Examination / Paper 1 5 Use of the Data Booklet is relevant to this question. The successive ionisation energies, in kJ mol–1, of an element E are given below. 870 1800 3000 3600 5800 7000 13200 Which of the following could be E? A Sn B As C Te D I 6 The gecko, a small lizard, can climb up a smooth glass window, The gecko has millions of microscopic hairs on its toes and each hair has thousands of pads at its tip. The result is that the molecules in the pads are extremely close to the glass surface on which the gecko is climbing. What is the attraction between the gecko’s toe pad and the glass surface? A co-ordinate bonds C ionic bonds B covalent bonds D van der Waals’ forces 7 Which type of structure does not correspond to its description of physical properties? type of structure physical properties A giant molecular high melting point, conducts electricity when in solution but not when in solid state B simple molecular low melting point, does not conduct in any state C metallic high melting point, conducts electricity when in solid state and molten D ionic high melting point, conducts electricity when molten but not when in solid state

5 8872 / YJC / 2015 / Preliminary Examination / Paper 1 8 The variation of equilibrium yield of product C for the following gas -phase reaction with changes in temperature and pressure, is represented in the diagram below. aA (g) + b B (g) ⇌ c C (g) ∆H = − 92.4 kJ mol-1 Which of the following options correctly relates the temperatures (T1 and T2) and the number of moles of gases (a,b and c). A T2 < T1 c < a + b B T2 < T1 c > a + b C T2 > T1 c < a + b D T2 > T1 c > a + b 9 For a reversible reaction, what is the effect of a catalyst on the rate constant, k 1 for the forward reaction, the rate constant, k1’ for the reverse reaction, and the equilibrium constant, Kc? k1 k1’ Kc A increases decreases no effect B decreases increases no effect C increases no effect increases D increases increases no effect T2 T1 pressure % yield 0f C

6 8872 / YJC / 2015 / Preliminary Examination / Paper 1 10 Given the following data and energy cycle: N2O4(g)  2NO2(g) ∆H = +57.9 kJ mol–1 NO(g) + 2 1 O2(g)  NO2(g) ∆H = 56.6 kJ mol–1 Determine the enthalpy change of the following reaction: 2NO(g) + O2(g)  N2O4(g) A +114.5 kJ mol–1 B 114.5 kJ mol–1 C +171 kJ mol–1 D 171 kJ mol–1 11 The lattice energies of magnesium fluoride and calcium chloride are − 2955 kJ mol – 1 and − 2255