Compassvale Sec 4Exp Prelim Chem P2 2024 QP

COMPASSVALE SECONDARY SCHOOL Secondary Four Express Preliminary Examination 2024 NAME CENTRE NUMBER S CLASS INDEX NUMBER ___________________________________________________________________________ CHEMISTRY 6092/02 Paper 2 23 August 2024 1 hour 45 minutes Candidates answer on the Question Paper. No Additional Materials are required. READ THESE INSTRUCTIONS FIRST Write your Centre number, class, index number and name 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, 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. The number of marks is given in brackets [ ] at the end of each question or part question. A copy of the Periodic Table is printed on page 21. The use of an approved scientific calculator is expected, where appropriate. __________________________________________________________________________ This document consists of 21 printed pages and 1 blank page. Set by: Ms Tay SW [Turn over

2 Section A Answer all questions. 1 (a) A list of symbols and formulae is shown. Al3+ Ar CH4 CO2 Cl2 Fe3+ H2 O2 O2‒ NO NO2 Zn2+ Answer the following questions about these symbols and formulae. Each symbol or formula may be used once, more than once or not at all. Which symbol or formula represents: (i) a compound which contributes to global warming, ……………………………………………………………………………………………........ [1] (ii) a compound which is taken in by plants during photosynthesis, ……………………………………………………………………………………………........ [1] (iii) a gas which comprises 0.93% of clean dry air, ………………………………………………………………….………………….………...... [1] (iv) a gas which bleaches damp litmus paper, ………………………………………………………………….………………….………...... [1] (v) an ion which forms a white precipitate that is insoluble in excess aqueous ammonia, ………………………………………………………………….……………………….…...... [1] (vi) an ion formed when an atom gains electrons? ………………………………………………………………….…………………………....... [1]

3 (b) Oxides of non-metals can be classified as acidic or neutral. Give an example of each and explain its classification. acidic oxide …………………………………………………………………………………….............. …………………………………………………………………………………………………............... neutral oxide ………………………………………………………………………………................... ………………………………………………………………………………………………….......... [2] [Total: 8] [Turn over

4 2 The experiment in Fig. 2.1 was set up to investigate the movement of gaseous ammonia and gaseous hydrogen chloride. Fig. 2.1 (a) The white powder forms on the tube due to the reaction between gaseous ammonia and gaseous hydrogen chloride. The white powder can be decomposed to form ammonia and hydrogen chloride. Write an equation for this reaction. ……………………………………………………………………………………………….............. [1] (b) The tube contains two pieces of Universal Indicator paper. Complete Table 2.1 to show the colours of each piece of Universal Indicator paper and the pH values at the end of the experiment. Table 2.1 Universal Indicator paper colour pH 1 2 [2] (c) Explain why the white powder does not form in the centre of the tube. ………………………………………………………………………………………………….............. ………………………………………………………………………………………………….............. ………………………………………………………………………………………………….............. ………………………………………………………………………………………………............. [3] [Total: 6] white powder forms on the tube here cotton wool soaked in concentrated hydrochloric acid cotton wool soaked in concentrated ammonia damp Universal Indicator paper 1 damp Universal Indicator paper 2

5 3 Niobium is a transition element while sodium is an element in Group 1 of the Periodic Table. (a) Give one similarity and one difference between the physical properties of niobium and sodium. similarity …………….…………………………………………………………………………............. ……………………………………………………………………………………………………........... difference …………….…….………………………………………………………………….............. ………………………………………………………………………………………...………............... [2] (b) Fig. 3.1 shows the structure of a molecule of niobium(V) chloride. Fig. 3.1 (i) What is unusual about the structure of niobium(V) chloride? ………………………………………………………………….…………………………........... ……………………………………………………………………………………………........ [1] (ii) State the formula of niobium(V) chloride. ………………………………………………………………….…………………………....... [1] (c) Sodium chloride has a much higher boiling point than niobium(V) chloride. Use ideas about structure and bonding to explain this difference in boiling points. ………………………………………………………………………………………………….............. ………………………………………………………………………………………………….............. ………………………………………………………………………………………………….............. ………………………………………………………………………………………………….............. ………………………………………………………………………………………………............. [3] [Total: 7] [Turn over

6 4 This question is about halogens. (a) Table 4.1 shows some information about three halogens, chlorine, bromine and iodine. Table 4.1 halogen melting point / °C boiling point / °C density / gcm‒3 chlorine ‒101 ‒35 0.03 bromine ‒7 59 3.12 iodine 114 184 4.93 (i) Describe the arrangement and movement of chlorine molecules at ‒10 °C. ………....……………………………………………………….…………………………........... ………....……………………………………………………….…………………………........... ……………………………………………………………………………………………........ [2] (ii) A student makes a comment about the densities of chlorine and bromine. ‘The difference in molecular mass of chlorine and bromine is not enough to account for the difference in densities.’ Explain why the student is correct. ………....……………………………………………………….…………………………........... ………....……………………………………………………….…………………………........... ……………………………………………………………………………………………........ [2] (b) Seawater contains potassium bromide. Bromine can be produced from seawater by displacement. (i) Which element can displace bromine? Explain your answer. Include any observations and an ionic equation in your explanation. ………....……………………………………………………….…………………………........... ………....……………………………………………………….…………………………........... ………....……………………………………………………….…………………………........... ………....……………………………………………………….…………………………........... ………....……………………………………………………….…………………………........... ……………………………………………………………………………………………........ [4]

7 (ii) Seawater also contains iodide ions. Describe a test, other than displacement, that can be used to show that seawater contains iodide ions. test …………….………………………………………………...………………………............. …………………………………………………………………….………………………........... result ……….….…….………………………………………………………………….............. ………………..………………………………………………………………...………............... [2] [Total: 10] [Turn over

8 5 A sample of black i