2024 HYSS Chem P2

HUA YI SECONDARY SCHOOL PRELIMINARY EXAM 2024 4-G3 NAME CLASS INDEX NUMBER CHEMISTRY 6092/02 PAPER 2 (XX) 20 August 2024 1 hour 45 minutes Additional Materials: Nil READ THESE INSTRUCTIONS FIRST Write your Name, Class, and Index Number on all the work you hand in. Write in dark blue or black pen. You may use an HB pencil for any diagrams or graphs. Do not use staples, paper clips, highlighters, glue, or correction fluid. Section A Answer all questions. Write your answers in the spaces provided. Section B Answer one question. Write your answers in the spaces provided. Section A 70 Section B 10 Total 80 The use of an approved scientific calculator is expected, where appropriate. The number of marks is given in brackets [ ] at the end of each question or part question. The Periodic Table is provided on page 27. This document consists of 27 printed pages and 1 blank page. © HYSS 2024 No part of this document may be reproduced in any form or transmitted in any form or by any means without the prior permission of Hua Yi Secondary School. Setter: Mr Chong KQ

2 2024_4-G3_ PRELIMS_ CHEMISTRY _PAPER 2 Section A [70 marks] Answer all questions in the spaces provided. 1 Fig. 1.1 shows part of the Periodic Table with some elements shown. Fig. 1.1 Each element may be used once, more than once or not at all. Using the symbols in the diagram, give one element which (a) has a giant molecular structure, …….…...................................................................................................................... [1] (b) combines with oxygen to form a gas which contributes to acid rain, ………...................................................................................................................... [1] (c) forms an ion of type X+ which has only three completely filled shells of electrons, …….…..................................................................................................................... [1] (d) forms a chloride that is soluble and with excess sodium hydroxide solution ; the white precipitate remains insoluble, …….…..................................................................................................................... [1] (e) is often used in galvanisation to prevent rusting. ……………………………………………………………………………………………... [1] [Total: 5]

3 2024_4-G3_ PRELIMS_ CHEMISTRY _PAPER 2 2 Silicon is a Group 14 element and is the second most abundant element in the Earth’s crust. It can be extracted by heating sand (silicon dioxide, SiO 2) with carbon to temperatures approaching 2200 C, producing carbon monoxide as a side product. Naturally occurring silicon is composed of three stable isotopes and the mass spectrum of the isotopes are as shown in Fig. 2.1. Fig. 2.1 (a) Write a balanced chemical equation for the reduction of sand into silicon. ………....................................................................................................................... [1] (b) Using the relative abundance of the 3 isotopes of silicon, calculate the relative atomic mass of silicon. relative atomic mass of silicon = ……………. [2] (c) Using the information in Fig. 2.1, explain why the isotopic mass for the 3 isotopes of silicon is different. ………....................................................................................................................... ………....................................................................................................................... ………....................................................................................................................... ………....................................................................................................................... [2] relative abundance/ % isotopic mass 92.21 28 29 30 4.70 3.09

4 2024_4-G3_ PRELIMS_ CHEMISTRY _PAPER 2 (d) Use ideas about bonding and structure to explain the high melting point of sand. ………....................................................................................................................... ………....................................................................................................................... ………....................................................................................................................... ………....................................................................................................................... [2] [Total: 7] 3 Fig. 3.1 shows the set-up used to investigate the relative reactivity of metals A, B, C and D. The metal strips and copper were first cleaned with sandpaper. Various metal strips were connected in turn with the copper sheet and the voltage recorded. Fig. 3.1 Table 3.1 gives the results of the investigation. Table 3.1 metal under test direction of electron flow in the external circuit voltage recorded/ v A A to Cu + 1.40 B B to Cu - 2.22 C A to C + 0.77 D A to D + 0.28 clip metal strip under test filter paper moistened with sodium choride solution copper sheet

5 2024_4-G3_ PRELIMS_ CHEMISTRY _PAPER 2 (a) Arrange the four metals A, B, C and D in decreasing order of reactivity. ………....................................................................................................................... [1] (b) Which of these metal(s) is/are less reactive than copper? Explain your answer using concepts of tendencies of electron flow. …….…...................................................................................................................... ………....................................................................................................................... [2] [Total: 3] 4 Six samples of metal carbonates are heated strongly until there is no further change in mass. Table 4.1 shows the mass of solid remaining at the end of the heating. Table 4.1 metal carbonate mass before heating /g mass after heating /g calcium carbonate 2.00 1.30 copper(II) carbonate 2.00 0.95 iron(II) carbonate 2.00 1.12 magnesium carbonate 2.00 1.29 sodium carbonate 2.00 2.00 zinc carbonate 2.00 1.24 (a) State and explain, with the use of information from Table 4.1, which of the above carbonates is the least thermally stable. …….…...................................................................................................................... ………....................................................................................................................... [2] (b) Explain why sodium carbonate has no change in mass as compared to the other carbonates in Table 4.1. …….…...................................................................................................................... ………....................................................................................................................... [1]

6 2024_4-G3_ PRELIMS_ CHEMISTRY _PAPER 2 (c) Metals are extracted from the metal carbonates by different methods. Suggest and e xplain the methods that would be suitable for the extraction of metals from the metal carbonates listed in Table 4.1. …….…...................................................................................................................... ………....................................................................................................................... [2] (d) Apart from the ease of thermal decomposition of metal carbonate, explain why the mass of solid obtained after heating is different for each metal carbonate.