RI 2020 Y5 Promo QP

1 © Raffles Institution 2020 9729/S/20 [Turn Over Name: ( ) Class: 21S0____ RAFFLES INSTITUTION 2020 Year 5 Promotional Examination HIGHER 2 CHEMISTRY 9729 30 September 2020 2 hours 30 minutes Additional Materials: Multiple Choice Answer Sheet Data Booklet 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 1 and 17. 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 35 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. Section C (40 marks) consists of 3 free-response questions. Answers to Sections B and C 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. This document consists of 26 printed pages 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 ed to penalty for writing answers in pencil. For Examiner’s Use Only C1 / 16 C2 / 12 C3 / 12

2 © Raffles Institution 2020 9729/S/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 What is the order of the following compounds in increasing melting point? MgO MgCl2 AlCl3 A AlCl3 < MgCl2 < MgO B AlCl3 < MgO < MgCl2 C MgO < MgCl2 < AlCl3 D MgCl2 < MgO < AlCl3 2 Water has a much higher boiling point than methane but a lower boiling point than silicon tetrabromide. compound H2O CH4 SiBr4 boiling point / °C 100 –162 153 Which statements correctly explain the observed trend? 1 The O–H bonds in water are stronger than the C–H bonds in methane but weaker than the Si–Br bonds in silicon tetrabromide. 2 Hydrogen bonds between water molecules are stronger than the instantaneous dipole-induced dipole interactions in methane but weaker than the instantaneous dipole -induced dipole interactions in silicon tetrabromide. 3 Water is a simple molecule while silicon tetrabromide is a giant molecule. A 1 and 3 only B 2 only C 2 and 3 only D 1, 2 and 3 3 When lanthanum iodate(V), La(IO3)3, is heated to 560 °C, it decomposes as shown below. lanthanum iodate(V) ⎯⎯→ lanthanum periodate(VII) + iodine + oxygen In this reaction, lanthanum does not change oxidation state. If the IO3–:I2 molar ratio in this reaction is 5:2, what is the formula of the periodate(VII) ion? A IO4– B