DHS Prelim P1 Ans

This question paper consists of 20 printed pages and 1 blank page. © DHS 2015 [Turn over Name: Index Number: Class: DUNMAN HIGH SCHOOL Preliminary Examination 2015 Year 6 H2 CHEMISTRY 9647/01 Paper 1 Multiple Choice 29 September 2015 1 hour Additional Materials: Optical Mark Sheet Data Booklet INSTRUCTIONS TO CANDIDATES 1 Write your name and class on this question paper. 2 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 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 You may use a calculator.

2 © DHS 2015 9647/01 [Turn Over Section A For each question, there are four possible answ ers, A, B, C, and D. Choose the one you consider to be correct. 1 The use of Data Booklet is relevant to this question. Peroxodisulfate ions convert iodide ions into iodine slowly. S2O8 2–(aq) + 2I–(aq)  2SO4 2–(aq) + I2(aq) The ra te of the re action can be increased by the addition of catalysts such as aqueous iron(III) ions. A possible catalyst reaction pathway involves the following steps: Step 1 2Fe3+(aq) + 2I–(aq)  2Fe2+(aq) aq) + I2(aq) Step 2 S2O8 2–(aq) + 2Fe2+(aq) aq)  2Fe3+(aq) + 2SO4 2–(aq) Which of the following statements is incorrect? A Fe2+ is a stronger reducing agent than I–. B S2O8 2– is a stronger oxidising agent than Fe3+. C The E cell for step 2 is more positive than step 1. D Aqueous cobalt(II) ions can be used as a catalyst for this reaction. 2 0.5 g of zinc powder was found to reduce an acidified solution of 25.50 cm 3 of 0.200 mol dm–3 VO2 +. Which one of the following is the reduced product of VO2 +? A VO3 – B VO2+ C V3+ D V2+

3 © DHS 2015 9647/01 [Turn Over 3 Which graph best represents the behaviour of a fixed mass of ideal gas at constant temperature? A B C D 4 The interhalogen compound BrF3 is a volatile liquid which autoionises as follows. 2BrF3 BrF2 + + BrF4 – The electrical conductivity of BrF3 decreases with increasing temperature. Which one of the following statement is correct? A The autoionisation process is endothermic and the shape of the anion is square planar. B The autoionisation process is exothermic and the shape of the cation is linear. C The autoionisation process is endothermic and the shape of the anion is tetrahedral. D The autoionisation process is exothermic and the shape of the cation is bent. pV p p  p V V

4 © DHS 2015 9647/01 [Turn Over 5 The reaction between gaseous hydrogen and iodine monochloride is highly exothermic. The two–step mechanism of the reaction is shown below: Step I: H2(g) + ICl(g) → HI(g) + HCl(g) Step II: HI(g) + ICl(g) → I2(g) + HCl(g) 3 experiments were carried out to study the rate of the above reaction. Experiment Number Initial concentration of H2 / mol dm–3 Initial concentration of ICl / mol dm–3 Initial reaction rate / mol dm–3 s–1 1 2.0 2.0 0.0034 2 4.0 1.0 0.0034 3 2.0 1.0 0.0017 Which of the following graphs most likely describes the energy profile of the above reaction? A B C D Energy Reaction Pathway Energy Reaction Pathway Energy Reaction Pathway Energy Reaction Pathway

5 © DHS 2015 9647/01 [Turn Over 6 Sulfuric acid, one of the most important industrial chemicals, can carry out several functions in chemical reactions. Three examples of industrial reactions in which sulfuric acid is used are shown below. Reaction 1 Al2O3 + 3H2SO4  Al2(SO4)3 + 3H2O Reaction 2 Cu + H2SO4  CuO + SO2 + H2O Reaction 3 (CH3)3COH + H2SO4  (CH3)2CCH2 + H2SO4 + H2O What is the function of sulfuric acid in each reaction? Reaction 1 Reaction 2 Reaction 3 A dehydrating oxidising catalytic B acidic acidic dehydrating C dehydrating oxidising catalytic D acidic oxidising dehydrating 7 H2PO4 – + HBO3 2– HPO4 2– + H2BO3 – The equilibrium constant for the reaction represented by the equation above is greater than 1.0. Which of the following gives the correct relative strengths of the acid and base in the reaction? Acids Bases A H2PO4 – > H2BO3 – and HPO4 2– > HBO3 2– B H2BO3 – > H2PO4 – and HBO3 2– > HPO4 2– C H2PO4 – > H2BO3 – and HBO3 – > HPO4 2– D H2BO3 – > H2PO4 – and HPO4 2– > HBO3 2– 8 The solubility of Pb(OH)2 in water at 25°C is 1.06 × 10–5 mol dm–3. What is the solubility of Pb(OH)2 in a buffer solution of pH 12.8 at the same temperature? A 1.06 × 10–5 mol dm–3 B 1.06 × 10–8 mol dm–3 C 1.19 × 10–12 mol dm–3 D 1.19 × 10–15 mol dm–3

6 © DHS 2015 9647/01 [Turn Over 9 A student was given aqueous H2CO3 and NaHCO3 of the same concentration. He was asked to make an acidic buffer of pH 7. Given that the two aqueous solutions are of the same concentration, what is the volume of each solution required to make the acidic buffer? (Ka of H2CO3 = 4.3 × 10–7 mol dm–3) Vol. of H2CO3(aq) / cm3 Vol. of NaHCO3(aq) / cm3 A 11.63 50.00 B 31.68 50.00 C 78.93 50.00 D 215.00 50.00 10 In an acidic solution, bromate(V) ions react with bromide to form bromine according to the following equation: BrO3 ─(aq) + 5Br─(aq) + 6H+(aq)  3Br2(aq) + H2O(l) Mixture Volume of BrO3 ─(aq)/ cm3 Volume of Br─(aq)/ cm3 Volume of H+(aq)/ cm3 Volume of water/ cm3 Relative rate of formation of Br2(aq) I 50 250 300 400 8 II 50 250 600 100 32 III 100 250 600 50 64 IV 50 125 150 675 1 Which of the following shows the correct rate law for the reaction above? A rate = k [Br−][BrO3 −][H+]2 B rate = k [Br−][BrO3 −][H+] C rate = k [Br−]2[BrO3 −][H+]2 D rate = k [Br−]2[BrO3 −][H+]

7 © DHS 2015 9647/01 [Turn Over 11 When an acidified solution of hydrogen peroxide is mixed with a solution of potassium iodide, the following reaction occurs: H2O2 + 2I– + 2H+  2H2O + I2 The order of reaction with respect to concentration of hydrogen peroxide may be determined by performing experiment(s) and then graphically analysing the results. Which of the following plot will not allow you to determine the order of respect to concentration of hydrogen peroxide conclusively? A B C D [I–] / mol dm–3 t / min [H2O2] / mol dm–3 rate [I–] = 0.2 mol dm–3 [I–] = 0.05 mol dm–3 [H2O2] / mol dm–3 Absorbance [I2] / mol dm–3 t / min [I–] = 0.10 mol dm–3, [H2O2] = 0.08 mol dm–3, [H+] = 0.10 mol dm–3 [I–] = 0.10 mol dm–3, [H2O2] = 0.10 mol dm–3, [H+] = 0.10 mol dm–3 [H2O2] = 2.0 mol dm–3, [H+] = 0.10 mol dm–3 [H2O2] = 1.0 mol dm–3, [H+] = 0.10 mol dm–3

8 © DHS 2015 9647/01 [Turn Over 12 Which one of the statements below concerning the Period 3 elements (Na to Ar) is correct? A The hydrides of the elements become more acidic from Na to Cl. B The maximum oxidation state is shown by sulfur. C The melting points of the elements decrease across the Period. D The ionic radius decreases across the Period. 13 The elements P and Q are in groups VI and VII respectively in the same period. Which of the following statements regarding P and Q is most likely to be true? A PQ2 is linear in shape. B PQ4 is a non–polar molecule. C P is more electronegative than Q. D The first ionisation energy of P will likely be less endothermic than that of Q. 14 Which of the following