RI 2021 Y5 Promo QP

1 Name: ( ) Class: 22S0______ RAFFLES INSTITUTION 2021 YEAR 5 PROMOTION EXAMINATION Higher 2 CHEMISTRY 9729 28 September 2021 2 hours 10 minutes Additional Materials: Multiple Choice Answer (OMR) Sheet Data Booklet READ THESE INSTRUCTIONS FIRST Write your name, index number and civics tutorial group in the spaces provided on the OMR Sheet, and the cover sheets on pages 1 and 17. Do not use staples, paper clips, glue or correction fluid. This paper consists of three sections, A, B and C. Section A (15 marks) Answer this section first. The OMR sheet will be collected after the first 30 minutes. There are fifteen 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 OMR Sheet. Read the instructions on the OMR 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 paper. Section B (35 marks) There are three questions in this section. Answer all questions. Answers to this section are to be written in the spaces provided in the question paper. Section C (25 marks) There are two questions in this section. Answer all questions. Answers to this section are to be written in the spaces provided in the question paper. The use of an approved scientific calculator is expected, where appropriate. This document consists of 25 printed pages. Write in dark blue or black pen. You may use a pencil for any diagrams or graphs. 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. For Examiner’s Use Only B1 / 14 B2 / 9 B3 / 12

2 © Raffles Institution 2021 9729/S/21 [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 An element forms a triatomic molecule, E. The Avogadro constant is L. How many atoms are present in 1 cm3 of gaseous E at room temperature and pressure? A L 24000 B 3L 24 C 3L 24000 D 3L 22700 2 H2S reacts with SO2 to give S and H2O. Assuming the reaction goes to completion, how many moles of H 2S and SO2 would result in a mixture containing equal numbers of moles of H2S and S? moles of H2S moles of SO2 A 3 1 B 4 2 C 4 4 D 5 1 3 The first seven ionisation energies of an element, M, in kJ mol–1 are shown below. 1402 ; 2856 ; 4578 ; 7475 ; 9445 ; 53270 ; 64360 M forms its only chloride by heating M with chlorine. What is the chloride of M formed? A M2+(Cl–)2 B M3+(Cl–)3 C MCl2 D MCl3

3 © Raffles Institution 2021 9729/S/21 [Turn Over 4 What is the order of increasing enthalpy change for the three reactions shown? Rb+(g) ⎯→ Rb2+(g) + e− ∆H1 Br – (g) ⎯→ Br(g) + e− ∆H2 Kr(g) ⎯→ Kr+(g) + e− ∆H3 A ∆H1 < ∆H2 < ∆H3 B ∆H1 < ∆H3 < ∆H2 C ∆H2 < ∆H1 < ∆H3 D ∆H2 < ∆H3 < ∆H1 5 Which molecule is not polar? A SF4 B XeF2 C CH2F2 D SO2 6 The table below shows the boiling points of three compounds with the same molecular formula, C4H8O. compound structure boiling point / oC butanal 74.8 2-methylpropanal 63.0 but-3-en-1-ol H2C=CHCH2CH2OH 113.5 Which statements account for the differences in boiling points? 1 There is weaker hydrogen bonding in butanal than in but-3-en-1-ol. 2 There is C=C bond in but-3-en-1-ol but not in the other two compounds. 3 There are stronger induced dipole attractions in butanal than in 2-methylpropanal. A 2 only B 3 only C 1 and 3 only D 1, 2 and 3

4 © Raffles Institution 2021 9729/S/21 [Turn Over 7 The conversion of graphite into diamond is an endothermic reaction. Which statements about graphite and diamond are correct? 1 The carbon–carbon bond in graphite is stronger than that in diamond because the carbon atoms in graphite are sp2 hybridised. 2 The enthalpy change of atomisation of diamond is less endothermic than that of graphite. 3 The enthalpy change of combustion of diamond is more exothermic than that of graphite. A 1 only B 3 only C 1 and 2 only D 1, 2 and 3 8 Equal masses of C l2 and Ne are placed in separate gas syringe s with the same initial volume. At constant temperature , the volume of each syringe is increased at the same constant rate. Assuming both gases behave ideally, which graph shows the results for both gases? A B C D Cl2 Ne pV time 0 0 Cl2 Ne pV time 0 Cl2 Ne p time 0 Cl2, Ne p time

5 © Raffles Institution 2021 9729/S/21 [Turn Over 9 Which row shows enthalpy changes of the same value? A ∆Hformation(H2O(l)) ∆Hcombustion(H2(g)) B ∆Hatomisation(I2(s)) 1 2  bond energy of I–I C ∆Hcombustion(C(s)) 2  bond energy of C=O D first ionisation energy of O first electron affinity of O 10 The enthalpy changes involved in the formation of K I(aq) from K(s) and I2(s) are shown below. ∆H1 ∆H2 ∆H3 ∆H4 K(s) + 1 2 I2(s) ⎯⎯→ K(g) + I(g) ⎯⎯→ K+(g) + I–(g) ⎯⎯→ KI(s) ⎯⎯→ KI(aq) Which statements are correct? 1 ∆Hformation(KI(s)) = ∆H1 + ∆H2 + ∆H3 2 ∆H3 = lattice energy of potassium iodide 3 ∆H4 = hydration energy of potassium iodide 4 ∆H2 = first ionisation energy of potassium – first electron affinity of iodine A 1 and 2 only B 1 and 4 only C 2 and 3 only D 3 and 4 only 11 Which reaction is less spontaneous at higher temperatures? A H2(g) ⎯→ 2H(g) B 2H2O(l) ⎯→ 2H2(g) + O2(g) C 2Na+(g) + O2−(g) ⎯→ Na2O(s) D CaCO3(s) ⎯→ CaO(s) + CO2(g)

6 © Raffles Institution 2021 9729/S/21 [Turn Over 12 The decomposition of X2(g) follows first-order kinetics. X2(g) ⎯→ 2X(g) 50 cm3 of X2(g) was allowed to decompose in a sealed gas syringe at room temperature and pressure. If the half -life of the decomposition is 20 min, calculate the time taken for the syringe to register a volume of 87.5 cm3 of gas. A 20 min B 40 min C 60 min D 80 min 13 The kinetics of the following reaction is studied by finding the time taken, t, for a coloured reactant, A, to decolourise. A + B + C ⎯→ D + E A series of experiments was carried out using different volumes of A, B and C. Each reaction mixture was made up to the same total volume with water and the initial rate can be approximated as follows. initial rate  volume of A time taken for decolourisation of A The following results were obtained. experiment volume of A added / cm3 volume of B added / cm3 volume of C added / cm3 volume of water added / cm3 t / s 1 10 10 5 25 10 2 10 10 10 20 10 3 10 20 10 10 5 4 20 10 5 15 10 5 30 5 5 10 y Which statements can be deduced from these results? 1 The value of y for experiment 5 is 20. 2 The reaction is zero-order with respect to A. 3 The reaction is an overall second-order reaction. A 3 only B 1 and 2 only C 1 and 3 only D 1, 2 and 3

7 © Raffles Institution 2021 9729/S/21 [Turn Over 14 A reaction, involving gaseous reactants and products, has an equilibrium constant which is independent of temperature. Which statement about the reaction is correct? A Ther