EJC Prelim H2 Chemistry Paper 1 QP

© EJC [Turn Over EUNOIA JUNIOR COLLEGE JC2 Preliminary Examination 2025 General Certificate of Education Advanced Level Higher 2 CHEMISTRY Paper 1 Multiple Choice 9729/01 19 September 2025 1 hour Additional Materials: Multiple Choice Answer Sheet Data Booklet READ THESE INSTRUCTIONS FIRST Write in soft pencil. Do not use staples, paper clips, glue or correction fluid. Write your name, civics group and registration number on the Answer Sheet in the spaces provided unless this has been done for you. There are thirty questions on this paper. Answer all questions. For each question there are four possible answers A, B, C and D. Choose the one you consider correct and record your choice in soft pencil on the separate Answer Sheet. Read the instructions on the Answer Sheet very carefully. Each correct answer will score one mark. A mark will not be deducted for a wrong answer. Any rough working should be done in this question paper. The use of an approved scientific calculator is expected, where appropriate. This document consists of 13 printed pages and 3 blank pages.

2 © EJC 9729/01/J2PE/25 1 Three particles approach an electric field at the same speed. They are deflected as they pass through the electric field. What could be the identities of particles X, Y and Z? X Y Z A 35 17Cl– 37 17Cl– 23 11Na+ B 6 3Li+ 7 3Li+ 1 1H– C 37 17Cl– 35 17Cl– 23 11Na+ D 7 3Li+ 6 3Li+ 1 1H– 2 Which of the following about calcium and copper is correct? A The outermost orbital of the atoms of both elements has the same shape. B Atom of both elements have orbitals of only 2 different shapes of various sizes. C Atom of both elements have the same number of electrons in the outermost shell. D Both elements form ions of 2+ charge with the electronic configuration of [Ar]. + – X Y Z

3 © EJC 9729/01/J2PE/25 [Turn over 3 The following diagrams show the structures of an element, one of its oxides and its halides. What could the element be? A aluminium B carbon C phosphorus D silicon 4 The boiling point of water (100 ºC) is greater than that of HF (20 ºC). Which statement is a correct explanation of the above? A Each hydrogen bond formed between water molecules is stronger than that formed between HF molecules. B There are more atoms in a water molecule than there are in an HF molecule, resulting in stronger intermolecular forces in water. C There are, on average, more hydrogen bonds between water molecules than there are between HF molecules. D The water molecule has stronger permanent dipole –dipole interactions than the HF molecule. 5 For a fixed mass of an ideal gas, which of the following graphs does not have the same general shape as the rest? ( = density of the gas; M = molar mass of gas) A p  against T B pV against M T C p against ρT D T p against V

4 © EJC 9729/01/J2PE/25 6 Which option correctly describes the species in terms of its behaviour as a Lewis base and as an Arrhenius acid? species Lewis base Arrhenius acid A HCl no yes B AlH3 yes no C NH3 no no D O2− yes yes 7 Use of the Data Booklet is relevant to this question. Based on its position in the Periodic Table, which properties will indium, In, be expected to possess? 1 In the vapour state, the chloride dimerises to form In2Cl6. 2 Its oxide dissolves in both acids and alkalis. 3 Its ionic salts are typically coloured. A 1 only B 1 and 2 C 2 and 3 D 1, 2 and 3 8 Metal peroxides decompose when heated to form metal oxides and oxygen gas. Which factor contributes to solid BaO₂ being more thermally stable than solid MgO₂? A The hydration enthalpy of Mg²⁺ ion is more exothermic than that of Ba²⁺ ion. B The lattice energy of BaO₂ is more negative than that of MgO₂. C The charge density of Ba²⁺ ion is lower than that of Mg²⁺ ion. D The O–O bond in O 2– 2 is weaker than the O=O bond in O2. 9 F2 reacts with BrO – z ions in a 2 : 1 molar ratio to form F− and BrO – 4 ions. What is the value of z? A 1 B 2 C 3 D 5

5 © EJC 9729/01/J2PE/25 [Turn over 10 Diamond is a pure form of carbon. The mass of a diamond can be measured in carats, where one carat is equivalent to 0.200 g of carbon. How many carats is a diamond made up of 3.01 × 1023 carbon atoms? A 0.4 B 2.5 C 30 D 60 11 The enthalpy change of formation of potassium bromide, KBr, can be calculated using a Born-Haber cycle. The enthalpy changes related to potassium and bromine are shown in the table. enthalpy change /kJ mol–1 K(s) → K(g) +90 Br2(g) → 2Br(g) +193 K(g) → K+(g) + e– +418 Br(g) + e– → Br–(g) –325 K+(g) + Br–(g) → KBr(s) –678 What is the enthalpy change of formation of KBr? A –302 kJ mol–1 B –399 kJ mol–1 C –958 kJ mol–1 D –1054 kJ mol–1

6 © EJC 9729/01/J2PE/25 12 When heated, magnesium carbonate decomposes to form carbon dioxide and magnesium oxide. A graphical plot of ΔG versus T, describing the change of the Gibbs free energy of the decomposition of magnesium carbonate with respect to temperature, is shown below. Using the information from the graph, what is the value of SꝊ for the decomposition reaction? A +6.04 × 102 J mol–1 K–1 B –6.04 × 102 J mol–1 K–1 C +1.61 × 102 J mol–1 K–1 D –1.61 × 102 J mol–1 K–1 13 Caesium-137 undergoes radioactive decay to form barium-137. This decay is a first-order reaction with a half-life of 30.2 years. How long would it take for the molar proportion of caesium to barium to reach a ratio 1:3 from pure caesium-137? A 30.2 years B 60.4 years C 90.6 years D 120.8 years

7 © EJC 9729/01/J2PE/25 [Turn over 14 The reaction of hydrogen peroxide with iodide ions in an acidic solution can be monitored by an initial rates method. H2O2(aq) + 2H+(aq) + 2I−(aq) → 2H2O(l) + I2(aq) The rate equation was found to be as follows: rate = k [H2O2][I−] What of the following mechanism correctly describes this reaction? A H2O2 + I− → H2O + IO− (slow) IO− + H+ → HIO (fast) HIO + H+ + I− → H2O + I2 (fast) B H2O2 + I− → H2O + IO− (slow) H2O2 + IO− → H2O + IO2− (fast) IO2− + I− + 4H+ → 2H2O + I2 (fast) C 2H+ + 2I − → 2HI (fast) 2HI + H2O2 → 2H2O + I2 (slow) D H2O2 + I− + H+ → H2O + HIO (fast) HIO + I− → OH− + I2 (slow) OH− + H+ → H2O (fast) 15 When steam is passed over white hot coke, a mixture of combustible gases is obtained. C(s) + H2O(g) b f k k   H2(g) + CO(g) ∆H = +131 kJ mol–1 When equilibrium has been established, which of the following correctly describes what would happen if a proposed change is made to this system? proposed change value of Kc forward rate constant, kf backward rate constant, kb A add catalyst no change increase increase B add more C(s) no change increase no change C increase volume increase decrease decrease D increase temperature increase increase decrease

8 © EJC 9729/01/J2PE/25 16 Water dissociates into H+ and OH– as shown. H2O  H+ + OH– The pH of water decreases at higher temperatures. Which statements are correct? 1 Water becomes acidic at higher temperatures. 2 The dissociation of water is endothermic. 3 The pOH decreases at higher temperatures. A 1 only B 3 only C 1 and 2 D 2 and 3 17 The graph shows the changes in pH when excess 0.10 mol dm−3 base solution is added gradually to y cm3 of 0.10 mol dm−3 acid solution. Which combination could have given these results? acid base y / cm3 A H2SO4 NH3 10 B H2SO4 NH3 5 C (COOH)2 KOH 10 D (COOH)2 KOH 5 18 Given the following solubility product, Ksp, which of the following statements is correct?

9 © EJC 9729/01/J2PE/25 [Turn over salt Ksp Ag2SO4 1.4 × 10‒5 PbSO4 1.6 × 10‒8 PbI2 7.1 × 10‒9 A All three Ksp values have the same unit. B PbSO4 has a lower solubility in pure water than PbI2. C Solubility product of Ag2SO4 decreases when added to sulfuric acid. D Whe