DHS 2026 Prelim P2 QP

This document has 24 pages. Any blank pages are indicated. © DHS 2026 [Turn over Name: Centre/Index Number: Class: DUNMAN HIGH SCHOOL Preliminary Examination Year 6 H2 CHEMISTRY Paper 2 Structured Questions You must answer on the question paper. You will need: Data Booklet 9476/02 14 September 2026 2 hours INSTRUCTIONS • Answer all questions. • Use a black or dark blue pen. You may use an HB pencil for any diagrams or graphs. • Write your name, centre number and index number in the boxes at the top of the page. • Write your answer to each question in the space provided. • Do not use an erasable pen. Do not use correction fluid or tape. • You may use an approved calculator. INFORMATION • The total mark for this paper is 75. • The number of marks for each question or part question is shown in brackets [ ]. For Examiner’s Use 1 10 2 11 3 15 4 14 5 12 6 13 Total 75

2 © DHS 2026 9476/02 Answer all questions in the spaces provided. 1 (a) (i) Group 2 nitrates decompose when heated strongly according to the following equation. M(NO3)2(s) → MO(s) + 2NO2(g) + 1 2O2(g) The thermal decomposition of Group 2 nitrates is similar to that of carbonates. State how the thermal decomposition temperature of Ca(NO 3)2 will differ from that of Sr(NO3)2. Explain your answer. ………………………………………………………………………………………….….…. ………………………………………………………………………………………….….…. ………………………………………………………………………………………….….…. ………………………………………………………………………………………….….…. ………………………………………………………………………………………….….…. ………………………………………………………………………………………….….…. ………………………………………………………………………………………….….…. ………………………………………………………………………………………….….…. ………………………………………………………………………………………….….…. ………………………………………………………………………………………….….…. ……………………………………………………………………………………………. [3] (ii) Be has no reaction with cold water while Ba reacts vigorously with cold water. Explain the difference in observations. ………………………………………………………………………………………….….…. ………………………………………………………………………………………….….…. ………………………………………………………………………………………….….…. ………………………………………………………………………………………….….…. ……………………………………………………………………………………………. [1]

3 © DHS 2026 9476/02 [Turn Over (b) State two basic assumptions of the kinetic theory as applied to an ideal gas. ………………………………………………………………………………………….….………… ………………………………………………………………………………………….….………… ………………………………………………………………………………………….….………… ………………………………………………………………………………………….….………… ………………………………………………………………………………………….….………… ………………………………………………………………………………………….….………… ………………………………………………………………………………………….….………[1] (c) A pure sample of Ca(NO 3)2 was completely decomposed in a 15 cm3 sealed test tube at 520 C. The sealed test tube can withstand a maximum pressure of 103421 Pa without cracking. You should ignore the partial pressure of the air in the test tube. (i) Calculate the maximum mass of Ca(NO3)2 that can be decomposed without cracking the sealed test tube. [3] (ii) Suggest why despite using the theoretical maximum mass in (c)(i), the test tube may still crack. You should disregard the effect of temperature on the structural integrity of the test tube. ………………………………………………………………………………………….….…. ………………………………………………………………………………………….….…. ………………………………………………………………………………………….….…. ……………………………………………………………………………………………. [2] [Total: 10]

4 © DHS 2026 9476/02 2 (a) Aluminium chloride is often called a ‘shapeshifter ’ as the hybridisation of the aluminium atom changes when anhydrous AlCl3 acts as a Lewis acid to form [A lCl4]– ion in the presence of chloride ions. (i) Explain what is meant by a Lewis acid. ………………………………………………………………………………………….….…. ……………………………………………………………………………………………. [1] (ii) Draw a ‘dot-and-cross’ diagram to show the bonding in an [AlCl4]– ion. Show outer electrons only. [1] (iii) Using the Valence Shell Electron Pair Repulsion (VSEPR) theory, predict the shape and bond angle of [AlCl4]–. Explain your reasoning. ………………………………………………………………………………………….….…. ………………………………………………………………………………………….….…. ………………………………………………………………………………………….….…. ………………………………………………………………………………………….….…. ………………………………………………………………………………………….….…. ………………………………………………………………………………………….….…. ………………………………………………………………………………………….….…. ……………………………………………………………………………………………. [2]

5 © DHS 2026 9476/02 [Turn Over (iv) Aluminium undergoes orbital hybridisation, similar to carbon. State the hybridisation of the aluminium atom in AlCl3. Hence explain how AlCl3 acts as a Lewis acid. ………………………………………………………………………………………….….... ………………………………………………………………………………………….….... ………………………………………………………………………………………….….... ………………………………………………………………………………………….….... ………………………………………………………………………………………….….... ………………………………………………………………………………………….….... ………………………………………………………………………………………….….... …………………………………………………………………………………………... [1] (v) Explain, in terms of polarising power of cation and polarisability of anion, why AlCl3 has a greater covalent character than NaF. ………………………………………………………………………………………….….... ………………………………………………………………………………………….….... ………………………………………………………………………………………….….... ………………………………………………………………………………………….….... ………………………………………………………………………………………….….... ………………………………………………………………………………………….….... ………………………………………………………………………………………….….... …………………………………………………………………………………………... [2]

6 © DHS 2026 9476/02 (b) Similar to AlCl3, FeCl3 can also function as a Lewis acid in organic reactions. (i) Write the full electronic configuration of Fe3+. …………………………………………………………………………………………... [1] (ii) Sketch, on Fig. 2.1, a diagram of the dz2 orbital present in Fe3+. x y z Fig. 2.1 [1] (iii) Table 2.1 shows the relative abundance of the four main stable isotopes of Fe. Table 2.1 isotope relative abundance (%) 54Fe 5.85 56Fe 91.75 57Fe 2.12 58Fe 0.28 Using the information in Table 2.1, calculate the relative atomic mass of Fe, to one decimal place. [1] (iv) Complete Table 2.2 for 57Fe3+. Table 2.2 species number of protons number of neutrons number of electrons 57Fe3+ [1] [Total: 11]

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8 © DHS 2026 9476/02 3 (a) Methanol is a versatile chemical that can be further utili sed to produce other useful chemicals. It is produced industrially by reacting carbon monoxide with hydrogen gas according to the equation shown below. reaction 1 CO(g) + 2H2(g) ⇌ CH3OH(g) H < 0 (i) An engineer introduced a mixture of carbon monoxide and hydrogen gas into a sealed vessel and it was allowed to reach equilibrium at a fixed temperature. Fig. 3.1 shows the total pressure in the vessel as reaction 1 proceeds. At time , t = 10 min , he then realised that he had used lower amount of carbon monoxide than expected so he introduced more carbon monoxide at t = 10 min and monitored the process till t = 30 min. Given that equilibrium was established at t = 20 min, complete the sketch in Fig. 3.1. Explain your reasoning. total pressure / Pa time, t / min 10 20 30 Fig. 3.1 ………………………………………………………………………………………….….…. ………………………………………………………………………………………….….…. ………………………………………………………………………………………….….…. ………………………………………………………………………………………….….…. ………………………………………………………………………………………….….…. ………………………………………………………………………………………….….…. ………………………………………………………………………………………….….…. ………………………………………………………………………………………….….…. ……………