RI 2020 Y5 Timed Practice QP

1 © Raffles Institution 2020 9729/J/20 [Turn Over RAFFLES INSTITUTION 2020 Year 5 Term 3 Timed Practice HIGHER 2 CHEMISTRY 9729 26 June 2020 2 hours 15 minutes Additional Materials: Multiple Choice Answer Sheet READ THESE INSTRUCTIONS FIRST DO NOT open this booklet until you are told to do so. Write your name, 6-digit exam index number and civics tutorial group in the spaces provided on the OMR Answer Sheet and the cover sheet on page 9. Shade in your 6-digit exam index number on the OMR Answer Sheet. This paper consists of three sections A, B and C. Section A (15 marks) consists of 15 multiple-choice questions. Record your answers to this section in soft pencil on the separate OMR A nswer Sheet. Your OMR Answer Sheet will be collected after the first 30 minutes. Section B (30 marks) consists of 3 structured questions. Answers to this section are to be written in the spaces provided in the question paper. Section C (35 marks) consists of 2 free-response questions. Answers to this section are to be written in the spaces provided in the question paper. You are reminded of the need for good English and clear presentation in your answers. The number of marks is given in brackets [ ] at the end of each question or part question. Write in dark blue or black pen. You may be subject to penalty for writing answers in pencil. This document consists of 25 printed pages and 0 blank page.

2 © Raffles Institution 2020 9729/J/20 [Turn Over Section A (15 marks) For each question there are four possible answers, A, B, C, and D. Choose the one you consider to be correct. 1 Which statement is correct? A The molar mass of a compound has the same units as its relative molecular mass. B One mole of a compound contains the same number of atoms as there are atoms in 12.0 g of carbon-12. C The relative atomic mass of fluorine is given by the following expression. weighted average mass of 1 molecule of fluorine 1 12 x mass of 1 atom of carbon-12 D 12.0 dm3 of oxygen gas contains the number of atoms as 24.0 dm3 of argon at room temperature and pressure. The following information is relevant for Questions 2 and 3. The reaction between urea, N2H4CO, and nitrous acid, HNO2, produces water, carbon dioxide gas and nitrogen gas. N2H4CO(aq) + 2HNO2(aq) → 3H2O(l) + CO2(g) + 2N2(g) 2 What is the change in the oxidation number of nitrogen fro m nitrous acid to nitrogen gas? A –1 B –3 C +3 D +5 3 In an experiment, 1 mol of urea was reacted with nitrous acid. The mass of unreacted urea was 6.0 g. What was the percentage of urea reacted? A 87.5% B 89.7% C 90.0% D 90.3%

3 © Raffles Institution 2020 9729/J/20 [Turn Over 4 The first six successive ionisation energies of an element Q are plotted in the following diagram. What is the electronic configuration of Q2+? A 1s2 2s2 2p2 B 1s2 2s2 2p6 C 1s2 2s2 2p6 3s2 D 1s2 2s2 2p6 3s2 3p2 5 “Mirror nuclei” are a pair of nuclei where the number of protons of element A equals the number of neutrons of element B and the number of protons of element B equals the number of neutrons in element A. Which of the following statements are correct? 1 Mirror nuclei have the same mass number. 2 11O and 11Li are mirror nuclei. 3 40Ar and 40Ca are mirror nuclei. A 1 and 2 only B 1, 2 and 3 only C 2 and 3 only D 1 only 0 4000 8000 12000 16000 20000 1 2 3 4 5 6 number of electron removed ionisation energy / kJ mol–1

4 © Raffles Institution 2020 9729/J/20 [Turn Over 6 Sodium cyanoborohydride is a reducing agent commonly used in organic synthesis. Its structure is shown below. How many  and  bonds are there in the cyanoborohydride anion?  bonds  bonds A 5 2 B 5 1 C 4 3 D 4 2 7 In which of the following pair does the first species have a bigger bond angle than the second species? A SF2 and NF4+ B NF4+ and CO32− C ClO3− and CO32− D ClO3− and SF2 8 Water has a much higher boiling point than methane. What are major reasons for this? 1 Strong hydrogen bonds exist between water molecules 2 The O–H bonds in water are stronger than the C–H bonds in methane 3 The water molecule contains more electrons than the methane molecule A 1, 2 and 3 B 1 and 2 only C 2 and 3 only D 1 only

5 © Raffles Institution 2020 9729/J/20 [Turn Over 9 Which of the following graphs shows the behaviour of ideal gases X and Y at constant temperature, where X has a higher molar mass than Y, and both samples have equal masses? A B C D 10 A fixed volume vessel contains 2.00 g of gas A at a pressure of 1.00 atm at 25 oC. When 3.00 g of inert gas B was added into the same vessel at the same temperature, the final pressure was found to be 2.50 atm. What is the ratio of the molar mass of gas A : gas B? A 1 : 1 B 5 : 3 C 2 : 3 D 4 : 9 p pV 0 Y X p pV 0 Y X p pV 0 X Y p pV 0 X Y

6 © Raffles Institution 2020 9729/J/20 [Turn Over 11 Use of the Data Booklet is relevant to this question. The temperature of a 250 cm3 sample of water was measured at 0.5 min intervals. At 2.0 min, 6.0 g of solid AlCl3 was added to the water and the mixture was stirred. The temperature measurements are shown in the following graph. Which of the following statements are correct? 1 Products of this reaction are energetically more stable than the reactants. 2 Heat loss to surroundings is accounted for via extrapolation to time = 0. 3 The heat change of the reaction is +364 kJ. A 1, 2 and 3 B 1 and 3 only C 2 and 3 only D 1 only

7 © Raffles Institution 2020 9729/J/20 [Turn Over 12 Use of the Data Booklet is relevant to this question. Phosphorus trioxide, P2O3, exists in the form of P4O6. It is formed when P 4 reacts with O2. The structures of P4 and P4O6 are shown below. What is the enthalpy change, in kJ mol–1, of the following reaction? P4(g) + 3 O2(g) → P4O6(g) A +1392 B –1392 C +2430 D –2430 13 Sulfur exists in two common forms at room temperature, rhombic sulfur and monoclinic sulfur. The combustion of both forms of sulfur produce sulfur dioxide and their respective standard enthalpy changes of combustion are shown below. S(monoclinic) = −297.2 kJ mol−1 S(rhombic) = −296.9 kJ mol−1 Which of the following deductions below are correct? 1 Rhombic sulfur is more stable than monoclinic sulfur. 2 Conversion of rhombic sulfur to monoclinic sulfur is endothermic. 3 Less energy is required to atomis e 1 mol of rhombic sulfur than 1 mol of monoclinic sulfur. A 1, 2 and 3 B 1 and 2 only C 1 and 3 only D 2 and 3 only

8 © Raffles Institution 2020 9729/J/20 [Turn Over 14 Which of the following processes has a negative change in entropy? A H2O(s) → H2O(l) B KNO3(s) + aq → KNO3(aq) C CaO(s) + H2O(l) → Ca(OH)2(s) D 2Al(s) + 6HCl(aq) → Al2Cl6(aq) + 3H2(g) 15 The following graph plots the change in Gibbs free energy, G, in kJ mol –1, against temperature, T, in K, for a particular reaction. Which of the following statements about the reaction are correct? 1 The reaction is exothermic. 2 There is an increase in disorder during the reaction. 3 The reaction becomes less exergonic as temperature increases. A 1 only B 1 and 2 only C 1 and 3 only D 2 and 3 only – END OF SECTION A – G T 0

9 © Raffles Institution 2020 9729/J/20 [Turn Over RAFFLES INSTITUTION 2020 Year 5 Term 3 Timed Practice H2 Chemistry COVER SHEET Name: ( ) C