SAJC Prelim P1 Qns

1 NAME Class ST ANDREW’S JUNIOR COLLEGE JC2 PRELIMINARY EXAMINATIONS Chemistry Higher 2 9729/01 Paper 1 Multiple Choice 18 September 2017 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 on the Answer Sheet in the spaces 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 separate Answer Sheet. Each correct answer will score one ma rk. 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 19 printed pages and 1 blank page.

2 1 During a laboratory practical exercise, a student tried to determine the concentration of Fe2+(aq) and Fe3+(aq) in a given mixture through two different experiments. 1. 25.0 cm 3 aliquot of the Fe 2+(aq) and Fe 3+(aq) mixture solution required 15.00 cm3 of 0.1 mol dm –3 of acidified KMnO 4 solution for complete oxidation. 2. Using another 25.0 cm3 aliquot, all the Fe3+(aq) was first reduced to Fe2+(aq) using zinc metal before requiring 34.20 cm3 of the same KMnO4 solution for complete oxidation. What is the concentration of Fe2+(aq) and Fe3+(aq) in the given mixture? A 0.012 mol dm–3 Fe2+(aq) and 0.0154 mol dm–3 Fe3+(aq) B 0.180 mol dm–3 Fe2+(aq) and 0.230 mol dm–3 Fe3+(aq) C 0.300 mol dm–3 Fe2+(aq) and 0.384 mol dm–3 Fe3+(aq) D 0.300 mol dm–3 Fe2+(aq) and 0.684 mol dm–3 Fe3+(aq) 2 A number of elements in the actinoid series are radioactive and undergo decay to other elements. The following equation is an example of such decay. Pu → element A + 9 He2 4 + 5 e–1 0 94 241 Which of the following gives the identity of element A? Mass number Atomic number A 205 81 B 205 86 C 223 81 D 237 90

3 3 Which of the following show s an increase in the bond angle of the compound from left to right? A NH3 H2S SiH4 B PH3 NH3 AlCl3 C PH3 PF3 PCl3 D XeF4 SCl6 CCl4 4 In which of the following does Statement II give a correct explanation for Statement I? Statement I Statement II 1 Magnesium has a higher melting point than sodium. Magnesium has more delocalised valence electrons which results in stronger metallic bonds. 2 Glycine, H2NCH2COOH, has a higher melting point than 2–hydroxyethanoic acid, HOCH2COOH. Glycine can form stronger hydrogen bonds than 2–hydroxyethanoic acid. 3 Chloromethane undergoes nucleophilic substitution more easily than fluoromethane. The C–Cl bond in chloromethane is weaker than the C–F bond in fluoromethane. A 2 and 3 B 1 and 2 C 1 and 3 D 1, 2, and 3

4 5 The graph of pV against p is plotted for an ideal gas at constant temperature for a fixed mass of gas at T1. Which diagram shows the new graph at a lower temperature at T2? A B C D p pV p pV p pV p pV p pV T1 T1 T1 T1 T1 T2 T2 T2 T2

5 6 The enthalpy change of formation of carbon monoxide and carbon dioxide are given below. ΔHf (CO)= –110 kJ mol–1 ΔHf (CO2)= –393 kJ mol–1 Which of these statements are correct? 1 Carbon dioxide is energetically more stable than carbon monoxide. 2 The enthalpy change of combustion of carbon is –283 kJ mol–1. 3 ΔHf (CO2) – ΔHc (CO) has the same value as enthalpy change of formation of CO. A 1 and 3 B 1 and 2 C 2 and 3 D 1 only 7 A raw egg white contains the protein, albumin, which is made of chains of amino acids that fold into specific and stable three-dimensional structure. Heating the protein in an egg white causes the intermolecular forces to break and “unfold” the protein. In this state, albumin is denatured and will readily coagulate to form an extensive protein network. What are the correct signs of ΔS, ΔH, and ΔG for denaturation of albumin during cooking? ΔS ΔH ΔG A + + – B + + + C – – + D – + – Albumin Coagualation Denaturation

6 8 The diagram shows the Maxwell –Boltzmann energy distribution curves for air molecules at room temperature and inside the car engines where it is being combusted. The letters P, Q, R and S refer to the separate areas. Which expression gives the fraction of the air molecules present inside the car engine? A S P B R+S P+Q+S C S P+Q+S D S P+Q Q Fraction of molecules with Energy S R P Energy EA

7 9 An experiment was carried out to investigate the kinetics of the reaction between ammonium peroxodisulfate, (NH4)2S2O8, an oxidising agent, and potassium iodide, KI, in the presence of a little starch. S2O82–(aq) + 2I–(aq) → 2SO42–(aq) + I2(aq) The volume of the (NH 4)2S2O8 and KI solutions in the mixture, together with the time taken for the mixture to darken for the various experimental runs are given below: Experiment Volume used / cm3 Time / s 1.0 mol dm–3 KI 0.040 mol dm–3 (NH4)2S2O8 H2O 1 10.0 5.0 25.0 170 2 15.0 5.0 20.0 113 3 15.0 10.0 15.0 56.5 4 20.0 20.0 0.0 ? Which of the following statements about the reaction is false? A The reaction can be catalysed by Fe(NO3)2(aq). B The reaction involves the formation of an intermediate. C The time taken for the mixture to darken in Experiment 4 is 40.5 s. D The slow step involves the reaction between 1 mole of (NH4)2S2O8 and 1 mole of KI.

8 10 Silver chloride establishes an equilibrium with the relatively stable complex ion, [Ag(NH3)2]+ AgCl(s) + 2NH3(aq) [Ag(NH3)2]+(aq) + Cl–(aq) Which of the following statements is correct? A When acid is slowly added to the mixture, a white precipitate is observed. B The Kc expression is Kc = [[Ag(NH3)2]+] [C𝑙−] [AgCl ] [NH3]2 C Added more NH3 to the solution when equilibrium is established will decrease its Kc value. D Removal of some AgCl(s) causes the position of equilibrium to shift left. 11 At a total pressure of 1 .2 atm, sulfur trioxide is 50% dissociated according to the following equation at 150 K. 2SO3 (g) 2SO2 (g) + O2(g) What is the mole fraction of oxygen in this equilibrium mixture? A 0.60 B 0.20 C 0.30 D 0.24 12 Which of the following mixtures when dissolved in large amount of water could act as buffer solutions? 1 2 mol of HI and 1 mol of CH3CH2NH2 2 2 mol of CH3COCl and 3 mol of NaOH 3 2 mol of CH3CH2NH2 and 1 mol of H2SO4 A 2 only B 2 and 3 C 1 and 3 D None of the above

9 13 The solubility of 2 sparingly soluble solids MX 2 and LY is being determined experimentally. Which of the following statements is always true? A The solubility product of MX2 increases with increasing temperature. B MX2 will always be more soluble than LY if MX2 has a higher Ksp value. C The Ksp value of LY can be calculated from any concentration of L+ and Y–. D Given that the solubility of LY is exothermic, the Ksp of LY will only change when temperature changes. 14 The following graphs show the variation of a property of the elements Na to P. Which of the following correctly describes the property of the graphs? Graph 1 Graph 2 Graph 3 A Electronegativity Melting point of oxide pH of oxide B Ionic radius Melting point of element pH of oxide C Covalent character Melting point of chlorides pH of chloride D Electronegativity Melting point of element pH of chloride Proton Number Proton Number Proton Number Graph 1 Graph 2 Graph 3

10 15 1.0 mol dm–3 aqueous solutions of three elements in Group 17 of the Periodic Table have standard electrode potentials as follows. X2(aq) + 2e– 2X–(aq) EƟ