MI 2018 H2 CHEM (9729 01) Answers Prelim

Class Adm No Candidate Name: This question paper consists of 11 printed pages and 1 blank page. 2018 Preliminary Examinations Pre-University 3 H2 CHEMISTRY 9729/01 Paper 1 Multiple Choice 21 Sept 2018 1 hour Additional materials: Multiple Choice Answer Sheet Data Booklet READ THESE INSTRUCTIONS FIRST Do not turn over this question paper until you are told to do so Write in soft pencil. Do not use staples, paper clips, glue or correction fluid. Write your name, class and admission number in the spaces provided at the top of this page and on the Multiple Choice Answer Sheet provided. 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 Multiple Choice Answer Sheet provided. Read the instructions on the Multiple Choice 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 question paper. The use of an approved scientific calculator is expected, where appropriate. FOR EXAMINER’S USE TOTAL (30 marks)

2 1 Use of the Data Booklet is relevant to this question. Which sample of gas below contains the same number of particles as 19.0 g of fluorine gas? 1 2.0 g of helium gas 2 10.1 g of neon gas 3 17.0 g of ammonia gas A 1 only B 3 only C 1 and 2 only D 1, 2 and 3 2 Arsenic in the form of arsenic trioxide, As 2O3, was used in the past as rat poison. To test for the presence of As2O3, 1.0 g sample containing some As 2O3 is dissolved and excess H 2S is then added to the solution. 0.492 g of As2S3 is precipitated as a result. The equation for the reaction is given below: As2O3 + 3H2S ⟶ As2S3 + 3H2O What is the percentage by mass of arsenic in the original sample? A 15.9% B 29.0% C 39.5% D 86.5% 3 Use of the Data Booklet is relevant to this question. Tin(II) ions can be used as a reducing agent. What volume of 0.025 mol dm -3 of tin(II) ions is needed to completely reduce 5 × 10-4 mol of potassium manganate(VII)? A 8.00 cm3 B 16.0 cm3 C 25.0 cm3 D 50.0 cm3

3 [Turn over 4 The graph below shows the 3 rd ionisation energies of elements A to I, which are consecutive elements with atomic number less than 20. Third ionisation energy elements Which of the following statements is correct? A The 3rd ionisation energy of B is the highest as it is the removal of an inner shell electron. B Element A is a noble gas. C Element E has a lower 3 rd ionisation energy than element D because of inter-electronic repulsion from the paired 2p electrons. D Element G has a higher 3rd ionisation energy than element F because of higher shielding effect. 5 A sample of 9Be2+ ions are passed through some charged electrical plates. The angle of deflection of the 9Be2+ ions is 12.0°. Another sample of doubly charged X ions are also passed through the same electrical plates and deflected at an angle of -6.75°. What is the mass number of X? A 4 B 8 C 10 D 16 ABCDEFGH I

4 6 Which of the following statements is true about graphite and diamond? 1 Only covalent bonds are present in the structures for both graphite and diamond. 2 The bond angle about the C-C-C is 109.5° for both graphite and diamond. 3 C-C covalent bonds in diamond are longer than the C-C covalent bonds in graphite A 1 only B 3 only C 1 and 2 only D 1 and 3 only 7 In which set of species do all three compounds have the same shape? A CO 2, NO2, SO2 B BF3, AlCl3, PBr3 C CH4, SiH4, GeH4 D BeF2, CO2, H2S 8 2.90 g of potassium fluoride was dissolved in 100 g of water. The temperature rise measured was 5.1°C. If the enthalpy change of hydration of K + and F - are -320 kJ mol -1 and -524 kJ mol-1 respectively, what is the lattice energy of potassium fluoride? Assume that specific heat capacity of water is 4.2 J g-1 K-1. A - 801 kJ mol-1 B - 887 kJ mol-1 C + 801 kJ mol--1 D + 887 kJ mol-1 9 Which of the following reactions has a positive entropy change? A 2SO2(g) + O2(g) ⟶ 2SO3(g) B CO2(g) + C(s) ⟶ 2CO(g) C Fe(s) + S(s) ⟶ FeS(s) D C2H4(g) + H2(g) ⟶ C2H6(g)

5 [Turn over 10 At room temperature and pressure, which of the following gases has the greatest deviation from ideal gas behaviour? A helium B sulfur dioxide C carbon dioxide D methane 11 Which of the following is a conjugate acid-base pair? A CO 2/CO32- B HCl/NaOH C H2O/OH- D H2SO4/SO42- 12 X, Y and Z react together to give some products as shown. X + Y + Z ⟶ products The rate equation of the reaction above can be written as rate = k[X][Y]. Which of the following graphs is correct of the reaction above? A B C D [X] rate time [X] [Y] rate time [Y]

6 13 Which of the following statements is true about enzymes? 1 Enzymes lose their catalytic properties at high temperatures. 2 They are specific towards particular substrates. 3 They help to break down larger molecules into smaller ones. A 1 and 2 only B 2 and 3 only C 1 only D 3 only 14 Consider the following reaction: CO(g) + 2H 2(g) ⇌ CH3OH(g) ∆H = -92 kJ mol-1 Which of the following statements is correct about the above reaction? A The equilibrium constant increases as a catalyst is added. B When more hydrogen gas is added to the system, the equilibrium position shifts left. C When temperature increases, the yield of the product increases. D When pressure increases, the yield of the product increases. 15 A mixture of powdered coal and steam at a pressure of 1 atm and a temperature of 1300 °C was allowed to reach equilibrium as shown in the equation below. H2O(g) + C(s) ⇌ H2(g) + CO(g) It was found that the total pressure had increased to 1.9 atm but the remaining steam had a partial pressure of only 0.1 atm. Which of the following shows the partial pressure of carbon monoxide and the value of Kp for this equilibrium? Partial pressure of CO / atm K p A 0.9 8.1 B 0.9 32.4 C 1.8 8.1 D 1.8 32.4

7 [Turn over 16 Sparingly soluble Ag2SO4 dissociates in aqueous solution according to the following equation. Ag2SO4(s) ⇌ 2Ag+(aq) + SO42-(aq) Given that the solubility product of Ag2SO4 is S, what is the concentration of [Ag+] in a saturated solution of Ag2SO4? A ࡿ 4൰ ଵ ଷ Bࡿ C ࡿ 2൰ ଵ ଷ Dሻ ଵ ଷ 17 Which of the following statements is true about aluminium chloride? 1 It forms an acidic solution in water. 2 It conducts electricity in the solid state. 3 It can dimerise through dative bonding. A 3 only B 1 and 2 only C 1 and 3 only D 1, 2 and 3 18 Group 2 nitrates decompose in this manner: M(NO3)2 ⟶ MO(s) + 2NO2(g) + ½O2(g) and require more energy for decomposition down the group. Which factor best explains this trend? A electronegativity of group 2 metals B stability of group 2 oxides C ionic radii of group 2 metal ions D lattice energy of group 2 nitrates

8 19 The use of Data Booklet is relevant to this question. What will be observed when a few drops of acidified aqueous hydrogen peroxide are added to an excess of aqueous potassium iodide? A The solution remains colourless and no effervescence occurs. B The solution turns brown and no effervescence occurs. C The solution remains colourless and effervescence occurs. D The solution turns brown and effervescence occurs. 20 Use of the Data Booklet is relevant to this question. A solution of tin(II) ions is mixed with dichromate(VI) ions. A green solution was observed. What is the standar