CJC Prelim H2 CHEM P1 qns

1 9647/01/CJC JC2 Preliminary Exam 2016 [Turn over CATHOLIC JUNIOR COLLEGE JC2 PRELIMINARY EXAMINATIONS Higher 2 CHEMISTRY 9647/01 Paper 1 Multiple Choice Wednesday 31 August 2016 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 and HT group on the Answer Sheet in the spaces provided. There are forty 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. The use of an approved scientific calculator is expected, where appropriate. This document consists of 17 printed pages and 1 blank page.

2 9647/01/CJC JC2 Preliminary Exam 2016 Section A For each question there are four possible answers, A, B, C and D. Choose the one you consider to be correct and record your choice in soft pencil on the separate Answer Sheet provided. 1 Use of the Data Booklet is relevant to this question. Arsenic(III) sulfide, As2S3, is a bright yellow solid which has been used as a pigment in paintings. When arsenic(III) sulfide is heated in air, it reacts with oxygen to give arsenic(III) oxide and sulfur(IV) oxide. 2As2S3 + 9O2  2As2O3 + 6SO2 What would be the mass of arsenic(III) oxide produced if 550 dm 3 oxygen, measured at room temperature and pressure, reacted with arsenic(III) sulfide? A 1010 g B 1070 g C 2010 g D 2160 g 2 Incomplete combustion of 20 cm 3 of a gaseous hydrocarbon gave carbon dioxide and carbon monoxide in a 6:1 ratio, as well as water vapour. It was found that the carbon dioxide took up a volume of 51.4 cm3 whereas the water vapour took up a volume of 80 cm3. All gas volumes are measured at the same temperature and pressure. What is the molecular formula of the hydrocarbon? A C2H4 B C2H6 C C3H6 D C3H8 3 Polythionates are a series of sulfur -oxo anions with the general formula S nO62‒, where n > 2. A simple example is tetrathionate ion, S4O62‒. Which of the following graphs best illustrates the variation in the average oxidation number of sulfur in SnO62‒ with n? average oxidation number of S 3 number of S atoms, n 0 A B C D

3 9647/01/CJC JC2 Preliminary Exam 2016 [Turn over 4 Which of the following species has the smallest bond angle around the central atom? A NCl3 B PCl3 C SO3 D BF3 5 Which of the following shows the correct bonds present in solid CHI3? A Covalent bonds only B Ionic bonds only C Covalent bonds & temporary dipole-induced dipole forces of attraction D Covalent bonds & permanent dipole-permanent dipole forces of attraction 6 Polymerisation is a process in which large number of small molecules (monomers) are joined together to form long–chain molecules. Considering that polymerisation is a spontaneous reaction, what are the correct signs of S and H for the process? S H A – – B – + C + – D + + 7 S4N4 is a thermoch romic solid which changes colour with temperature. S 4N4 has a cage structure as shown in the diagram. Given the following data, what is the average bond energy of dissociation of S-N, in kJ mol-1? ΔHf° (S4N4) = +460 kJ mol-1 ΔHat° (sulfur) = +279 kJ mol-1 ΔHat° (nitrogen) = +497 kJ mol-1 (S-S) bond energy of dissociation in S4N4 = +204 kJ mol-1 A +150 B +280 C +395 D +559

4 9647/01/CJC JC2 Preliminary Exam 2016 8 At 25 C, a dented ping pong ball has an internal volume of 31.0 cm 3 and internal pressure of 110 kPa. It is then placed in a water bath maintained at 60 C, which returned the ball to its original spherical shape with internal volume of 33.5 cm3. Assuming ideal gas behaviour, what is the pressure of air inside the ball a t 60 C in its original spherical shape? A 101 kPa B 114 kPa C 122 kPa D 244 kPa 9 Gas X decomposes to two other gases, Y and Z, according to the following equation: 2X(g) ⇌ 3Y(g) + Z(g) The graph below shows the decomposition of 1.0 mol of pure gas X in the presence of a catalyst at various temperatures. Which one of the following statements about the above system is correct? A The decomposition of X is endothermic. B The Kp of the system decreases with increasing temperature. C The percentage decomposition of X is 40 % at 300 oC. D The system becomes less disordered when it reaches equilibrium state. 1.0 0.8 moles of X remaining time 300 °C 0.6 0.4 0.2 0.0 250 °C

5 9647/01/CJC JC2 Preliminary Exam 2016 [Turn over 10 Malonic acid, HO2CCH2CO2H, is a weak dibasic acid. Malonic acid is titrated against 20.0 cm 3 of sodium hydroxide of the same concentration, the following pH-volume curve is obtained. At which point on the titration curve is the mixture most able to resist pH change upon addition of a small amount of aqueous acid or base? 11 The following is the reaction for compound XY, XY(g) → X(g) + Y(g) If the rate constant for the reaction is 5.78 x 10 ‒3 s‒1, what is the time taken for the concentration of a sample of XY to decrease from 1.80 mol dm-3 to 0.225 mol dm‒3? A 120 s B 240 s C 360 s D 480 s 12 The reaction between C and D is as follows: C + 2D  2E In an experiment to investigate the effect of concentrations on the rate of reaction, the following results were obtained at constant temperature. Experiment [C] / mol dm-3 [D] / mol dm-3 Initial rate / mol dm‒3s‒1 1 1.0 1.0 0.0008 2 1.0 2.0 0.0016 3 1.0 3.0 x 4 2.0 2.0 0.0032 What is the value of x? A 0.0008 B 0.0016 C 0.0024 D 0.0032 pH Vol of malonic acid / cm3 A I – B – C D 20 10 5 2.5

6 9647/01/CJC JC2 Preliminary Exam 2016 13 The following graph show s how a property of the elements in Period 3, from Na to P, or their compounds, varies with proton number. What property is shown by the graph? A Melting point of element B Melting point of oxide C pH of aqueous chloride D Electrical conductivity of element 14 Which of the following statements about calcium, strontium and barium is correct? A The magnitude of the hydration energy of the M 2+ ion increases from calcium to barium B The energy required for the process M (g)  M2+ (g) + 2e - increases from calcium to barium. C The reducing power decreases from calcium to barium. D The reactivity of the elements with water increases from calcium to barium. 15 When 1.0 g of each of the following Group II metals is added to cold water and any gas produced is collected at 25 °C and 1 atm, which sample will most likely produce the largest volume of gas? A Mg B Ca C Sr D Ba 16 Which statement about the trends in the properties of the halogens is correct? A The volatility of halogens increases down the group. B The electronegativity of halogens increases down the group. C The reactivity of halogens with hydrogen decreases down the group. D The bond dissociation energy of halogens increases down the group. 11 12 13 14 15 proton number

7 9647/01/CJC JC2 Preliminary Exam 2016 [Turn over 17 “Bromine tablets” are used as disinfectants. It is a source of HC lO(aq) and HBrO(aq), both of which are oxidising agents. HBrO destroys bacteria, fungi and algae via its oxidising property in the process. HClO is a stronger oxidising agent than HBrO and helps to sustain the effectiveness of the bromine tablets. What is the likely role of HClO in relation to HBrO? A Oxidises Br– to BrO B Oxidises Br– to Br2 C Reduces BrO to Br D Reduces BrO– to Br2 18 When drops of aqueous ammoni a are added to a solutio