VJC Prelim P1 QP and Ans

© VJC 2018 9729/01/PRELIM/18 [Turn over VICTORIA JUNIOR COLLEGE JC 2 PRELIMINARY EXAMINATION Higher 2 CHEMISTRY 9729/01 Paper 1 Multiple Choice 19 September 2018 1 hour Additional Materials: Multiple Choice Answer Sheet Data Booklet READ THESE INSTRUCTIONS FIRST Write in soft pencil. Do not use staples, paper clips, highlighters, glue or correction fluid. Write your Exam Number, name and CT group on the Multiple Choice Answer Sheet. There are thirty questions. 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 choices in soft pencil on the separate Multiple Choice Answer Sheet. Read the instructions on the Answer Sheet very carefully. Each correct answer will score one mark. No mark will 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 8 printed pages.

2 © VJC 2018 9729/01/PRELIM/18 1 The Avogadro constant is L. How many neutrons are present in 24 dm 3 of chlorine gas, measured at r.t.p? A 17 L B 18.5 L C 37 L D 71 L 2 A carbon sample contains a mixture of 12C and 14C isotopes. When 1.000 g of this sample is burned completely in 16O2. The mass of CO2 formed is 3.629 g. What is the percentage by mass of the 12C isotope in this sample? A 85.0% B 88.6% C 90.0% D 91.4% 3 When phosphoryl chloride, POC l 3, dissolves in water, it gives a mixture of phosphoric acid and hydrochloric acid. How many moles of sodium hydroxide would be needed to neutralise the solution formed by adding one mole of POCl3 to excess water? A 3 B 4 C 5 D 6 4 Which of the following pairs have similar shapes and the first species has a smaller bond angle than the second species? 1 SiCl 4, PF4+ 2 PH3, NH3 3 SO32–, CO32– A 1 only B 2 only C 1 and 2 only D 2 and 3 only 5 But-2-enedioic acid, HC(CO2H)=C(CO2H)H, exists as a pair of cis-trans isomers. The cis isomer has a lower melting point than the trans isomer. Which of the following statements is correct about but-2-enedioic acid? 1 In the solid state, both the cis and trans isomers have the same density. 2 Intramolecular hydrogen bonding is present in the cis isomer. 3 The cis isomer is less polar than the trans isomer. A 2 only B 1 and 2 only C 1 and 3 only D 2 and 3 only 6 Which of the following statements about prop-1,2-diene, H 2C=C=CH2, is not correct? A The C=C in prop-1,2-diene is stronger than the C=C in ethene. B The two π-bonds in prop-1,2-diene are perpendicular to each other. C There are only two sp 2 hybridised carbon atoms in a prop-1,2-diene molecule. D Prop-1,2-diene is a planar molecule.

3 © VJC 2018 9729/01/PRELIM/18 [Turn over 7 Which of the following statements is not correct? A Under very high pressure, HC l gas behaves more ideally than Cl2 gas. B Ideal gas molecules have zero size. C Real gas molecules behave more ideally under low pressure and high temperature. D There are no collisions between ideal gas molecules. 8 The lattice energies of the compounds, magnesium oxide, magnesium bromide, sodium oxide and sodium bromide are given below. Which of the following values corresponds to the lattice energy of magnesium bromide? A –752 kJ mol –1 B –2440 kJ mol –1 C –2481 kJ mol –1 D –3790 kJ mol –1 9 The enthalpy changes of formation of gaseous ethene and ethane are +52 kJ mol –1 and –85 kJ mol–1 respectively at 298 K. Consider the following reaction. C 2H4(g) + H2(g) → C2H6(g) Which of the following statements is correct? A ΔS reaction is positive. B The enthalpy change of the reaction is –137 kJ mol –1. C If ethene is converted to ethane via four stages instead of one as shown above, the enthalpy change of the reaction will be less exothermic. D The addition of a catalyst will cause the enthalpy change of reaction to be more exothermic. 10 Ammonium chloride readily dissolves in water at room temperature. During the process, the temperature of the solution decreases. Which of the following statements is correct? 1 Dissolution of ammonium chloride is favoured due to the entropy change. 2 Dissolution of ammonium chloride is not spontaneous at very low temperature. 3 The sum of the hydration energies of ammonium ion and chloride ion is less exothermic than the lattice energy of ammonium chloride. A 1, 2 and 3 B 1 and 2 only C 2 and 3 only D 1 only

4 © VJC 2018 9729/01/PRELIM/18 11 Three experiments are conducted to determine the rate equation for a reaction between sulfuric acid and sodium thiosulfate. The volumes used and the time taken for the precipitate to form are shown below. What could be a suitable value for x? A 5 B 10 C 20 D 30 12 Lead is the final product formed by a series of changes in which the rate-determining stage is the radioactive decay of uranium-238. This radioactive decay is a first-order reaction with a half-life of 4.5 × 10 9 years. What would be the age of a rock sample, originally lead-free, in which the molar ratio of uranium to lead is now 1:7? A 1.5 × 10 9 years B 2.25 × 10 9 years C 9.0 × 10 9 years D 1.35 × 10 10 years 13 A reversible reaction is catalysed. Which of the following statements about this reaction are correct? 1 The catalyst alters the mechanism of the reaction. 2 The catalyst reduces the activation energy for both the forward and the backward reaction. 3 The catalyst alters the composition of the equilibrium mixture. A 1, 2 and 3 B 1 and 2 only C 2 and 3 only D 1 only 14 Pure nitrosyl chloride gas, NOC l, was heated at 320 °C in a 2.0 dm 3 vessel. At equilibrium, 30% of the NOC l gas has dissociated according to the equation below and the total pressure was p atm. 2NOCl(g) ⇌ 2NO(g) + Cl2(g) What is the numerical value of the equilibrium constant, Kp, at 320 °C? A 17.9 p B 41.7 p C 0.0240 p D 0.0276 p 15 What is the pH of the resultant solution when 100 cm 3 of 0.10 mol dm–3 aqueous NH4Cl and 40 cm3 of 0.15 mol dm–3 aqueous NaOH are mixed at 25 °C? (pKb of NH3 = 4.75) A 4.57 B 4.93 C 9.07 D 9.43 Experiment Volume of H 2SO4 / cm3 Volume of Na2S2O3 / cm3 Volume of water / cm3 Time / s 1 20 20 20 30 2 40 20 0 15 3 x 20 0 15

5 © VJC 2018 9729/01/PRELIM/18 [Turn over 16 The value of the solubility product, Ksp, of silver chromate(VI), Ag2CrO4, is 2.5 × 10–22 at 25 °C. Which statement about silver chromate( VI) is correct? A The units for Ksp of silver chromate(VI) are mol2 dm–6. B Addition of nitric acid will cause Ksp value of silver chromate(VI) to increase. C Addition of nitric acid will cause the solubility of silver chromate( VI) to increase. D The solubility of silver chromate( VI) in water is 1.58 × 10–11 mol dm–3. 17 Which of the following changes does not alter the reduction potential measured for a Cl 2/Cl– half-cell? A Adding water into the half-cell. B Placing the half-cell in an ice-water bath. C Adding silver ions into the half-cell. D Introducing an additional 1 bar of inert gas into the half-cell. 18 When a large current was passed through an aqueous copper( II) sulfate solution with two inert electrodes, there was liberation of x mol of copper and y dm 3 of oxygen, measured at r.t.p. How many moles of electrons passed through the circuit?