RI 2019 Prelim P1 QP

© Raffles Institution 2019 9729/01/S/19 [Turn Over RAFFLES INSTITUTION 2019 YEAR 6 PRELIMINARY EXAMINATION Higher 2 CHEMISTRY 9729/01 Paper 1 Multiple Choice 30 September 2019 1 hour Additional Materials: Multiple Choice Answer Sheet Data Booklet READ THESE INSTRUCTIONS FIRST Do not open this question booklet until you are told to do so. Write in soft pencil. Do not use staples, paper clips, highlighters, glue or correction fluid. Write your name, class and index number in the spaces provided on the Answer Sheet. There are thirty questions in this section. 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. 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 the question booklet. This document consists of 15 printed pages.

2 © Raffles Institution 2019 9729/01/S/19 [Turn Over For each question, there are four possible answers, A, B, C, and D. Choose the one you consider to be correct. 1 Copper has two stable isotopes, 63Cu and 65Cu. Which statement is correct? A 63Cu2+ ion has fewer protons than 65Cu+ ion. B The electronic configuration of 63Cu+ is [Ar] 3d9 4s1. C 63Cu+ ion has the same number of neutrons as 65Cu3+ ion. D 63Cu+ ion has fewer unpaired electrons than 65Cu3+ ion. 2 Information about some compounds are given below. compound chemical formula boiling point / °C hydrogen peroxide H2O2 150 dihydrogen disulfide H2S2 70.7 hydrazine N2H4 114 Which statements about these compounds are correct? 1 All three molecules contain at least one  bond formed by sp3–s orbital overlap. 2 The H–O–O bond angle in H2O2 is greater than the H–S–S bond angle in H2S2. 3 H2S2 has the weakest instantaneous dipole-induced dipole interaction. 4 N2H4 has less extensive hydrogen bonding than H2O2. A 1 and 2 only B 2 and 3 only C 1 and 4 only D 1, 3 and 4 only 3 Which compound has the highest solubility in water? A CH3CH2CH2NH2 B CH3CH2CO2Na C CH3CH2CH2Cl D CH3CH2CH2CH3 4 An air-filled plastic ball has a volume of 30.0 cm3. At 22 oC and 100 kPa, a slightly dented plastic ball of volume 27.5 cm3 is filled with air. To restore its spherical shape, the air inside the dented ball is heated to 57 oC. The pressure of air inside the ball increases and creates a uniform outward force. Assuming that the air inside the plastic ball behaves ideally, what is the pressure of air inside the plastic ball at 57 oC when its shape is restored? A 92 kPa B 103 kPa C 112 kPa D 238 kPa

3 © Raffles Institution 2019 9729/01/S/19 [Turn Over 5 0.010 mol of the chlorides of Al, Si and P were added separately to 1.0 dm3 of water. Which graph shows the correct trend of the pH of the resulting mixtures? A B C D 6 Use of the Data Booklet is relevant to this question. Which statements regarding the Group 17 elements and their hydrides are correct? 1 HI is more volatile than HBr because of the weaker bond strength between H and I atoms. 2 HF is thermally more stable than H I because of the str onger bond strength between H and F atoms. 3 Cl2 is a stronger oxidising agent than Br 2 because of the stronger bond strength between Cl atoms. A 2 only B 1 and 3 only C 2 and 3 only D 1, 2 and 3 only Al Si P pH Al Si P pH Al Si P pH Al Si P pH Al Si P Al Si P Al Si P Al Si P

4 © Raffles Institution 2019 9729/01/S/19 [Turn Over 7 Complete combustion of ethyl mercaptan, CH3CH2SH, produces carbon dioxide, water and sulfur dioxide, as shown. reaction 1 2CH3CH2SH + 9O2 ⎯⎯→ 4CO2 + 6H2O + 2SO2 In an experiment, it was found that complete combustion of 17.0 g of ethyl mercaptan raised the temperature of 1000 g of water in a calorimeter from 25 oC to 85 oC. This process is 60% efficient and the specific heat capacity of water is 4.18 J g–1 K–1. What is the enthalpy change of reaction 1? A –550 kJ mol–1 B –1099 kJ mol–1 C –1527 kJ mol–1 D –3054 kJ mol–1 8 Under acidic conditions, iodine reacts readily with propanone to form 1-iodopropanone as shown below. CH3COCH3(aq) + I2(aq) ⎯⎯⎯→ CH3COCH2I(aq) + HI(aq) The rate of the reaction can be calculated from the following expression. rate of reaction  volume of I2(aq) used time taken for the colour of iodine to disappear The time taken for the colour of iodine to disappear is tabulated below. experiment volume of 0.1 mol dm–3 CH3COCH3 used/cm3 volume of 0.1 mol dm–3 I2 used/cm3 volume of 0.1 mol dm–3 H+ used/cm3 volume of water added/ cm3 time taken for the colour of I2 to disappear/ min 1 40.0 20.0 40.0 0.0 1 2 40.0 20.0 20.0 20.0 2 3 20.0 20.0 40.0 20.0 2 4 40.0 10.0 40.0 10.0 0.5 5 40.0 10.0 10.0 40.0 x Which statements are correct? 1 The units for the rate constant is mol–1 dm3 min–1. 2 The time taken for the colour of I2 to disappear in experiment 5 is 2 min. 3 Using 0.2 mol dm–3 I2 will not change the time taken for each experiment. A 1 and 2 only B 1 and 3 only C 2 and 3 only D 1, 2 and 3 only H+(aq)

5 © Raffles Institution 2019 9729/01/S/19 [Turn Over Questions 9 and 10 refer to the following information regarding ozone depletion. 9 Ozone naturally decomposes to oxygen according to the equation below. 2O3(g) → 3O2(g) Cl• radicals, formed from chlorofluorocarbon compounds (CFCs) in the upper atmosphere, speeds up the reaction through a chain reaction involving the following steps: Step 1: Cl• + O3  ClO• + O2 fast Step 2: ClO• + O3 Cl• + 2O2 slow K1 is the equilibrium constant of step 1 and k2 is the rate constant of step 2. Which statements are correct? 1 Cl• functions as a catalyst of the chain reaction. 2 ClO• functions as a catalyst of the chain reaction. 3 Step 2 has a lower activation energy than step 1. 4 Step 2 has a lower activation energy than the uncatalysed reaction. A 1 and 2 only B 1 and 4 only C 1, 2 and 4 only D 2, 3 and 4 only 10 Which is the correct overall rate equation for the catalysed decomposition of ozone? A rate = k2[Cl•][O3] B rate = k2[ClO•][O3] C rate = k2K1[Cl•][O3]2 D rate = k2K1 l• 2 3 2 C[ ][O ] [O ] K1 k2

6 © Raffles Institution 2019 9729/01/S/19 [Turn Over 11 Methanol can be synthesi sed from hydrogen and carbon monoxide using a suitable catalyst at 480 K and a pressure of 3 x 106 Pa. 2H2(g) + CO(g)  CH3OH(g) H = –90.6 kJ mol–1 After the reaction mixture reached equilibrium under the above conditions, the temperature was increased to 550 K. Which option correctly describes the changes which take place? Kp is the equilibrium constant, and kf and kb are the rate constants for the forward and backward reactions respectively. yield of CH3OH Kp kf kb A increase increase increase decrease B decrease increase increase increase C decrease decrease increase increase D decrease decrease decrease increase 12 NH3 and BF3 forms a solid adduct NH3BF3 via dative covalent bonding. NH3(g) + BF3(g)  NH3BF3(s) Kp is the equilibrium constant of the above reaction. Which of the following expressions gives the concentration, in mol dm –3, of NH3(g) at 298 K? A   p3 1 BF K B 3 pBF 1 P K C BF3 p 1 (8.31)(298)P K D 3 pBF (8.31)(1000)(2 1 98)P K

7 © Raffles Institution 2019 9729/01/S/19 [Turn Over 13 Two aqueous solutions of HF and HCl were prepared at pH 3. It w