2022 JPJC Prelim P1 Question Paper and answer

© Jurong Pioneer Junior College [Turn Over NAME CLASS 21S JURONG PIONEER JUNIOR COLLEGE JC2 PRELIMINARY EXAMINATION 2022 CHEMISTRY 9729/01 Higher 2 Paper 1 Multiple Choice 22 September 2022 1 hour Candidates answer on separate paper. 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, class and exam index number on the Answer Sheet in the spaces provided unless this has been done for you. There are thirty questions on this paper. Answer all questions. For each question there are four possible answers A, B, C or D. Choose the one you consider correct and record your choice in soft pencil on the separate Answer Sheet. Read the instructions on the 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 booklet. The use of an approved scientific calculator is expected, where appropriate. This document consists of 13 printed pages.

2 © Jurong Pioneer Junior College 9729/01/J2 PRELIMINARY EXAM/2022 1 Use of the Data Booklet is relevant to this question. The table shows the forth, fifth, sixth, seventh , eighth and ninth ionisation energies of an element. Which element has these ionisation energies values? 4th 5th 6th 7th 8th 9th Ionisation Energy / kJ mol−1 5900 7100 8700 11000 13500 42000 A Si B P C Cl D Ar 2 Ethanedioate ions, C2O42–, are oxidised by hot acidified, aqueous potassium manganate( VII) according to the following equation. 2MnO4–(aq) + 5C2O42–(aq) + 16H+(aq) → 2Mn2+(aq) + 10CO2(g) + 8H2O(l) What volume of 0.020 mol dm –3 potassium manganate(VII) is required to oxidise completely 1.0 x 10–3 mol of the salt K2C2O4? A 20 cm3 B 40 cm3 C 50 cm3 D 125 cm3 3 Propanone and dichloromethane are common organic solvents used in the laboratory. Propanone is soluble in water but dichloromethane is not. Which of the following statements best accounts for this? A Propanone is a polar molecule but dichloromethane is non-polar. B A hydrogen bond forms between the hydrogen in propanone and the oxygen of a water molecule. C A hydrogen bond forms between the oxygen in propanone and the hydrogen of a water molecule. D Propanone has a smaller relative molecular mass than dichloromethane. propanone dichloromethane

3 © Jurong Pioneer Junior College 9729/01/J2 PRELIMINARY EXAM/2022 [Turn Over 4 Nitrogen oxides (NOx) can be formed from the reaction of nitrogen with oxygen in car engines. It can dissolve in water to form nitric acid which causes acid rain. Which of the following statements are correct? 1 N atom in NO3− is sp2 hybridised. 2 NO and NO2 contain an unpaired electron. 3 NO and NO2 have no net dipole moment. A 1 only B 1 and 2 C 2 and 3 D 1, 2 and 3 5 The value of pV is plotted against p for 2 gases, A and B, where p is the pressure and V is the volume of the gas. Which of the following could be identities of the gases? gas A gas B A 0.5 mol of CH4 at 25 ºC 0.5 mol of CH4 at 50 ºC B 0.5 mol of NH3 at 25 ºC 0.5 mol of NH3 at 323 ºC C 0.5 mol of CH4 at 25 ºC 1 mol of NH3 at 25 ºC D 1 mol of NH3 at 25 ºC 0.5 mol of CH4 at 25 ºC

4 © Jurong Pioneer Junior College 9729/01/J2 PRELIMINARY EXAM/2022 6 Travellers to countries with cold climate may sometimes use heat packs to keep warm. One example is the sodium ethanoate heat pack. This consists of a supersaturated solution of sodium ethanoate and a small metal disc containing very small crystals of sodium ethanoate. When the disc is broken, the small crystals of sodium ethanoate are released into the solution and act as nucleation sites to catalyse the crystallisation reaction of sodium ethanoate. Which line gives the signs of ∆H, ∆S and ∆G for the overall process? ∆H ∆S ∆G A - - - B - - + C + + - D + + + 7 A student investigated the kinetics of the reaction between 1.00 mol dm –3 potassium iodide and 0.0500 mol dm–3 sodium peroxodisulfate. S2O82−(aq) + 2I−(aq) → 2SO42−(aq) + I2(aq) The two reactants were mixed in the presence of a known amount of sodium thiosulfate and a few drops of starch. The time taken for an intense blue colour to be observed was recorded. Experiment number Volume used / cm3 Time / s KI Na2S2O8 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 z What is the value of z? A 11 B 21 C 85 D 1360

5 © Jurong Pioneer Junior College 9729/01/J2 PRELIMINARY EXAM/2022 [Turn Over 8 Gas A decomposes to two other gases, B and C, according to the equation: 2A(g) ⇌ 3B(g) + C(g) ∆H = +x kJ mol–1 Which of the following correctly describes what will happen if a proposed change is made to this system at equilibrium? proposed change value of Kc position of equilibrium A add inert solid no change shift left B increase pressure no change shift right C increase temperature increase shift right D add catalyst increase no change 9 The graph shows the result of an investigation of the initial rate of hydrolysis of maltose by the enzyme amylase. In the experiments, the initial concentration of maltose was varied, but that of amylase was kept constant. Which conclusions can be deduced from these results? 1 When [maltose] is low, the rate is first order with respect to [maltose]. 2 When [maltose] is high, the rate is independent of [maltose]. 3 When [maltose] is high, the rate is independent of [amylase]. A 1 only B 1 and 2 only C 2 and 3 only D 1, 2 and 3 10 Aqueous solutions of aluminium salts are acidic. They contain [Al(H2O)6]3+ ions. Ka for [Al(H2O)6]3+ = 1.0  10−5 mol dm−3 What is the pH of 0.01 mol dm−3 AlCl3? A 2.5 B 3.5 C 5.0 D 6.0 [maltose]se]

6 © Jurong Pioneer Junior College 9729/01/J2 PRELIMINARY EXAM/2022 11 Pure water undergoes dissociation as shown in the equation below. H2O ⇌ H+ + OH– At 40°C, the [H+] is found to be 10–6.8 mol dm–3. Which of the following statements is incorrect? A The dissociation of water is an endothermic process. B Water is acidic at 40oC. C At 40oC, the value of pKw is 13.6. D Both H+ and OH− ions are of the same concentration for pure water at 40oC. 12 The pH change when 0.100 mol dm –3 CH3CO2H is added dropwise to 10.0 cm 3 of 0.100 mol dm–3 KOH(aq) is given in the graph below. At which point on the graph does pH = p Ka, where Ka is the acid dissociation constant of the weak acid?

7 © Jurong Pioneer Junior College 9729/01/J2 PRELIMINARY EXAM/2022 [Turn Over 13 The use of Data Booklet is relevant to this question. Peroxodisulfate ions convert iodide ions into iodine slowly. S2O82–(aq) + 2I–(aq) → 2SO42–(aq) + I2(aq) The rate of the reaction can be increased by adding catalysts such as aqueous iron(III) ions. A possible pathway of a catalyst reaction involves the following steps: Step 1 2Fe3+(aq) + 2I–(aq) → 2Fe2+(aq) + I2(aq) Step 2 S2O82–(aq) + 2Fe2+(aq) → 2Fe3+(aq) + 2SO42–(aq) Which statement about the reaction is incorrect? A S2O82– is a stronger oxidising agent than Fe3+. B The reaction between S2O82− and I− is slow because the Ecell value is small. 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. 14 Use of the Data Booklet is relevant to this question. A cell is set up by connecting a Cu 2+/Cu half-cell and an acidified Cr 2O72−/Cr3+ half-cell under standard conditions. Which of the following correctly describes the effect on the e.m.f of the cell when the respective change is made? change effect on e.m.f