RI 2018 Y5 Promo QP

1 © Raffles Institution 2018 9729/S/18 [Turn Over RAFFLES INSTITUTION 2018 Year 5 Promotion Examination HIGHER 2 CHEMISTRY 9729 28 September 2018 2 hours 40 minutes Additional Materials: Multiple Choice Answer Sheet Data Booklet Writing Paper READ THESE INSTRUCTIONS FIRST DO NOT open this booklet until you are told to do so. Write your name and civics tutorial group in the spaces provided on the OMR sheet, cover sheets on pages 2 and 14 and writing paper. This paper consists of three sections A, B and C. Section A (15 marks) consists of 15 multiple-choice questions. Answer this section first. The OMR sheet will be collected after the first 30 minutes. Record your answers to this section in soft pencil on the separate OMR Answer Sheet. Section B (35 marks) consists of 3 structured questions. Answers to this section are to be written in the spaces provided in the question paper. Section C (40 marks) consists of 3 free-response questions. Answers to this section are to be written on the writing paper provided. You are to begin each question on a fresh page of 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 subjected to penalty for writing answers in pencil. At the end of the examination, fasten your answers to Section C and the cover sheet on page 2 securely together. Answers to Sections B and C are to be handed in separately. This document consists of 23 printed pages. This document is copyrighted, please do not reproduce it without permission

2 © Raffles Institution 2018 9729/S/18 [Turn Over RAFFLES INSTITUTION 2018 Year 5 Promotion Examination H2 Chemistry COVER SHEET Name: ( ) Class: For Examiner’s Use Only Section Marks C1 / 11 C2 / 15 C3 / 14 Fasten your answers to Section C and this cover sheet securely together. C This document is copyrighted, please do not reproduce it without permission

3 © Raffles Institution 2018 9729/S/18 [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 When sulfur is boiled with sodium hydroxide solution, the initial reaction results in the formation of S2– and SO32– ions. What is the mole ratio of S : S 2– : SO32– in the balanced equation for this reaction? A 2 : 1 : 1 B 3 : 2 : 1 C 3 : 1 : 2 D 4 : 1 : 3 2 In an experiment, 10 cm3 of a gaseous compound, CxHySz, was exploded with 100 cm3 of oxygen (in excess). One of the products is SO 2(g). After cooling to room temperature, the volume of the gaseous mixture was found to be 90 cm 3, but this decreased to 70 cm3 when the mixture was bubbled through aqueous alkali. What is the molecular formula of this compound? A C6H4S2 B C2H6S2 C C2H6S D CH4S 3 Use of the Data Booklet is relevant to this question. Iron and nickel are transition metals which often form ions with a charge of 2+. Which statement concerning the atoms and ions of these two elements is correct? A Ni2+ ion has a smaller ionic radius than Fe2+ ion. B Ni atom has a lower first ionisation energy than Fe atom. C Fe2+ ion and Ni atom are isoelectronic. D In the same electric field, Ni2+ ion will be deflected more than Fe2+ ion. 4 Use of the Data Booklet is relevant to this question. Paramagnetism is a form of magnetism exhibited by species which contain unpaired electrons. These species can be attracted by an external magnetic field. Which of the following species is not paramagnetic? A Cl+ B V3+ C O– D Cu+ This document is copyrighted, please do not reproduce it without permission

4 © Raffles Institution 2018 9729/S/18 [Turn Over 5 Cyclopentadiene is an organic molecule with a structure as shown below. In the presence of a base, one of its hydrogens can be removed to form the planar cyclopentadienyl anion which is stabilised by resonance. cyclopentadiene cyclopentadienyl anion Which statement about these species are correct? 1 Cyclopentadiene is a planar molecule. 2 All carbon atoms in cyclopentadienyl anion are sp2 hybridised. 3 The carbon-carbon bonds in the cyclopentadienyl anion are of different lengths. A 1 only B 2 only C 3 only D 2 and 3 only 6 Which of the following correctly represents ideal gas behaviour as shown by the graph? y-axis x-axis variable(s) held constant A p V n and T B p 1 T n and V C pV p n and T D pV T n H H Base H y x 0 base This document is copyrighted, please do not reproduce it without permission

5 © Raffles Institution 2018 9729/S/18 [Turn Over 7 Which class of reaction always has a positive enthalpy change? A atomisation B combustion C formation D solution 8 Which equation represents a reaction that is spontaneous at all temperatures? A Q(g) → R(s) + 2S(g) ∆H > 0 B 2T(s) + 3U(g) → 4V(aq) ∆H < 0 C 2W(l) → X(g) ∆H < 0 D Y(g) → Z(g) ∆H > 0 9 The reaction of graphite and steam is shown below. C(s) + H2O(g) ⇌ H2(g) + CO(g) The graph below represents the volume of hydrogen gas formed at two different temperatures, T1 and T2, with the same initial amount of reactants. Which statement about the reaction is correct? A The forward reaction is exothermic. B The addition of more carbon will shift the position of equilibrium to the right. C The equilibrium constant, Kc, increases with increasing temperature. D The temperature T2 is greater than T1. volume of H2 / cm3 time / s T1 T2 This document is copyrighted, please do not reproduce it without permission

6 © Raffles Institution 2018 9729/S/18 [Turn Over 10 The energy profile of a chemical reaction, A + 2B → 2C, is shown below. What can be deduced from the energy profile? 1 The reaction is second order with respect to B. 2 The rate determining step is a bimolecular reaction. 3 The reaction is a catalysed reaction. A 1 and 2 only B 1 only C 2 and 3 only D 1, 2 and 3 only 11 Lead is the final product formed by a series of changes in which the rate -determining step is the radioactive decay of uranium -238. This radioactive decay is a first -order reaction with a half-life of 4.5 x 109 years. How long would it take for a rock sample, originally lead- free, to contain a molar proportion of uranium to lead of 1 : 3? A 1.5 x 109 years B 2.25 x 109 years C 9.0 x 109 years D 1.35 x 109 years A + 2B AB + B 2C energy progres s of reaction This document is copyrighted, please do not reproduce it without permission

7 © Raffles Institution 2018 9729/S/18 [Turn Over 12 The graph shows how ∆G  changes with temperature for the reaction shown. W(g) + X(g) ⇌ Y(g) + Z(g) Equimolar amounts of W and X were introduced into a sealed container and allowed to reach equilibrium. At which points will the equilibrium concentration of X be smaller than that of Y? A 1 and 2 only B 1 only C 2, 3 and 4 only D 3 and 4 only 13 PCl5 can be prepared from the chlorination of PCl3. PCl3(g) + Cl2(g) PCl5(g) Equal amounts of reactants with a