2021 MI Prelim H2 Chemistry P1 (9729 01)

Class Adm No Candidate Name: This question paper consists of 11 printed pages and 1 blank page. 2021 Preliminary Examination Pre-University 3 H2 CHEMISTRY 9729/01 Paper 1 Multiple Choice 21 Sep 2021 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 For each question there are four possible answers, A, B, C, and D. Choose the one you consider to be correct. 1 Which of the following contains the same number of stated particles as the number of atoms in 19.0 g of fluorine gas? 1 Number of molecules in 2.0 g of hydrogen gas 2 Number of ions in 58.5 g of sodium chloride solid 3 Number of atoms in 14.0 g of nitrogen gas 4 Number of atoms in 12.0 g of graphite A 3 only B 1, 3 and 4 only C 2, 3 and 4 only D 1, 2, 3 and 4 2 20 cm3 of an unknown hydrocarbon was completely combusted in excess oxygen gas. Upon cooling back to room temperature and pressure, the total volume of gases was 50 cm3 less than the initial total volume. After passing the remaining gases through KOH(aq), the volume of gases further decreased by 80 cm3. What is the molecular formula of the unknown hydrocarbon? A C2H4 B C4H4 C C4H6 D C4H8 3 Which of the following statements is incorrect about the following reaction? 3VO2– + 2H+ → VO3– + 2VO + H2O A It is a displacement reaction. B The oxidation number of V in VO3– is +5. C VO2– is acting as a reducing agent. D VO2– is acting as an oxidising agent.

3 [Turn over 4 Use of the Data Booklet is relevant to this question. A copper rod weighing 15 g was dipped into 50 cm3 of 2.00 mol dm–3 AgNO3 solution. Silver crystals were observed to grow on the copper rod after a while. Which of the following statements are correct? 1 The EcellO of the reaction is +1.14V. 2 The solution turns blue. 3 6.35 g of copper would have reacted upon completion of reaction. A 1 only B 2 only C 2 and 3 only D 1, 2 and 3 5 Which of the following statements is not true about lithium? A It has a naturally occurring isotope which contains 3 neutrons. B It has a naturally occurring isotope which contains 4 neutrons. C It has the full electronic configuration 2s1. D It forms an ion with a +1 oxidation number. 6 Which of the following properties can be explained by hydrogen bonding? 1 The higher density of ice compared to liquid water. 2 The ability of water glider insects to float on water. 3 Ethanoic acid having an apparent molecular mass of 120.0 in non-polar solvents. A 1 and 2 only B 1 and 3 only C 2 and 3 only D 1, 2 and 3

4 7 Two elements D and E have the following properties. D E Melting point / °C 3600 –38 Appearance Dull Shiny Electrical conductivity when solid Yes Yes What are the likely identities of D and E? D E A SiO2 H2 B MgO Si C Si Na D C Hg 8 Which of the following statements best explains the following observation? Melting point of NaBr / °C 747 Melting point of MgBr2 / °C 711 A The size of the anion electron cloud is large and easily distorted. B NaBr has a larger magnitude of lattice energy than MgBr2. C There are more bromide ions in MgBr2 than in NaBr. D Magnesium has a higher charge and smaller size than sodium. 9 Which of the following statements about the standard enthalpy change of neutralisation is true? A It has a constant magnitude of 57.3 kJ mol–1. B It has a smaller magnitude for the reaction between a weak acid and strong base. C It is defined as the energy released when 1 mole of an acid reacts with 1 mole of a base. D It is an endothermic reaction.

5 [Turn over 10 Which of the following statements best describes why the enthalpy change of solution for lithium chloride, LiCl(s), is more exothermic than that for sodium fluoride, NaF(s)? A The ∆HhydrationO of Li+(g) is more exothermic than that of Na+(g). B The ∆HhydrationO of F–(g) is more exothermic than that of Cl–(g). C The lattice energy of LiCl(s) is more exothermic than that of NaF(s). D The 1st electron affinity of sodium is more exothermic than that of lithium. 11 What is the identity of the gas which has a density of 89.8 g m–3 at 7862 Pa and 22 °C? Assume the gas behaviour to be ideal. A He B Ne C N2 D H2 12 Which of the following is a conjugate acid-base pair? A HCl, H+ B H2SO4, SO42– C CO2, H2CO3 D NH3, NH4+ 13 The half-life for a certain first order reaction is 2 hours. How much time is required to form 25% of the products? A 0.8 hours B 2 hours C 3 hours D 4 hours

6 14 A reaction between NO and H2 has the following suggested mechanism. I: 2NO ⇌ N2O2 (fast) II: N2O2 + H2 ⇌ N2O + H2O (slow) III: N2O + H2 → H2O + N2 (fast) Which of the following correctly describes the rate equation? A rate = k [NO]2 B rate = k [NO]2[H2] C rate = k [NO]2[N2O2][H2] D rate = k [N2O2][H2] 15 Which of the following factors, when increased, will affect the position of equilibrium for the following reaction? CO(g) + H2O(g) ⇌ CO2(g) + H2(g) ΔH < 0 1 Concentration of CO(g) 2 Total pressure 3 Temperature 4 Volume of the container A 1 only B 1 and 3 only C 1, 3 and 4 only D 2 and 4 16 Nitrogen dioxide, NO2(g), was placed into a closed vessel of fixed volume and allowed to reach dynamic equilibrium. The equilibrium has a Kc value of 4.0 × 10–2 at a certain temperature. 2NO2(g) ⇌ N2O4(g) What is the initial concentration of NO2(g) if its equilibrium concentration was 0.50 mol dm–3? A 0.48 mol dm–3 B 0.51 mol dm–3 C 0.52 mol dm–3 D 0.70 mol dm–3

7 [Turn over 17 Given the formula, ΔG = –RT ln Kc, which of the following reactions will have an equilibrium constant value that is greater than 1 at all temperatures? A CH4(g) + H2O(g) ⇌ CO(g) + 3H2(g) ΔH > 0 B C3H8(g) + 5O2(g) ⇌ 3CO2(g) + 4H2O(g) ΔH < 0 C N2(g) + 3H2(g) ⇌ 2NH3(g) ΔH < 0 D NH4Cl(s) ⇌ NH4+(aq) + Cl–(aq) ΔH > 0 18 Which of the following mixtures will form an alkaline buffer? A 1 mole of CH3COOH and 1 mole of CH3COO–Na+ B 2 moles of CH3COOH and 1 mole of NaOH C 2 moles of CH3CH2NH2 and 1 mole of NaOH D 2 moles of CH3CH2NH2 and 1 mole of HCl 19 The Kw of water is 5.13 × 10–13 mol2 dm–6 at 100 °C. What is the pH of water at 100 °C? A 6.14 B 7.00 C 7.16 D 12.29 20 An aqueous solution of compound G (pKa = 4.70) is titrated against an aqueous solution of compound H (pKa = 13.8). Which of the following is the most suitable indicator for the titration? Indicator pH Range A α-Naphthyl red 3.7-5.0 B Bromocresol purple 5.2-6.8 C Bromophenol blue 6.2-7.6 D Thymolphthalein 9.4-10.6

8 21 Solid sodium carbonate is gradually added in small amounts to a solution containing a mixture of 0.0100 mol dm–3 of Ag+ ions and 0.0100 mol dm–3 of Cu2+ ions until in excess. Which of the following observations are correct? [Ksp (Ag2CO3) = 8.1 × 10–12; Ksp (CuCO3) = 2.5 × 10–10] A Only a white precipitate of Ag2CO3 will be seen. B Only a green precipitate of CuCO3 will be seen. C A green precipitate of CuCO3 will be seen fi