2025 Prelim P1 (for exchange) H2 Chem HCI

This document consists of 15 printed pages and 1 blank page. HWA CHONG INSTITUTION C2 Preliminary Examination Higher 2 CANDIDATE NAME CT GROUP 2 4 S CENTRE NUMBER S INDEX NUMBER CHEMISTRY Paper 1 Multiple Choice 9729/01 22 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. Complete the information on the Answer Sheet as shown below. 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 booklet. The use of an approved scientific calculator is expected, where appropriate.

2 © Hwa Chong Institution 2025 9729/01/C2 Preliminary Examination 1 The successive ionisation energies of an element X are given below. 1st 2nd 3rd 4th 5th 6th ionisation energy / kJ mol−1 950 1800 2700 4800 6000 12300 What could be the formula of the chloride X? A XCl B XCl2 C XCl4 D XCl5 2 In which row are G and H atoms or ions of different isotopes of the same element? G H number of electrons charge nucleon number number of electrons charge nucleon number A 8 0 18 10 −2 18 B 17 +1 37 16 0 34 C 16 0 36 18 0 38 D 20 0 42 18 +2 40 3 Which pair of species has a similar shape? A AlCl3 and PCl3 B BF3 and NH3 C SF4 and XeF4 D PH4+ and BF4ˉ

3 © Hwa Chong Institution 2025 9729/01/C2 Preliminary Examination [Turn Over 4 A small bulb with a capacity of 10 m3 is connected to another with a capacity of 30 m3. Before connection, the pressure in the smaller bulb is 50 kPa and that in the larger bulb is 120 kPa. If all measurements are made at the same temperature, what is the pressure in the combined arrangement after connection? A 67.5 kPa B 85 kPa C 103 kPa D 170 kPa 5 Which statement is correct? A The relative isotopic mass of an element is the mass of one atom of an isotope of the element relative to 1 12 the mass of one atom of 12C. B The relative atomic mass of an element is the mass of one atom of the element relative to 1 12 the mass of one atom of 12C. C The relative molecular mass of a compound is the average mass of one molecule of the compound relative to the mass of one atom of 1H. D The relative formula mass of an ionic compound is the average mass of one formula unit of the ionic compound relative to the mass of one atom of 12C. 6 The relative abundance of all the isotopes present in a sample of germanium are shown. What is the relative atomic mass of germanium calculated from these data? A 72.6 B 72.8 C 73.8 D 74.0 relative abundance 70 71 72 73 74 75 76 77 mass of isotope 19.01 24.96 7.76 41.0 8.59

4 © Hwa Chong Institution 2025 9729/01/C2 Preliminary Examination 7 The combustion of magnesium in oxygen is shown in the equation below. Mg(s) + 1 2 O2(g) → MgO(s) Some enthalpy changes are given below. MgO(s) + 2HCl(aq) → MgCl2(aq) + H2O(l) H = −89 kJ mol–1 Mg(s) + 2HCl(aq) → MgCl2(aq) + H2(g) H = −435 kJ mol–1 2H2(g) + O2(g) → 2H2O(l) H = −572 kJ mol–1 What is the enthalpy change of combustion for magnesium? A −632 kJ mol–1 B −918 kJ mol–1 C −1262 kJ mol–1 D −1352 kJ mol–1 8 Assuming the pressure of each system remains at 1 atm, which processes show an increase in entropy? 1 1 mol of Cl2(g) at 298 K is heated to 373 K. 2 1 mol of Cl2(g) at 298 K is added to 1 mol of N2(g) at 298 K. 3 1 mol of Cl2(g) at 1000 K is photolysed according to the following equation. Cl2(g) → 2Cl•(g) 4 1 mol of Cl2(g) at 298 K is reacted with iodine according to the following equation. Cl2(g) + 1 3 I2(s) → 2 3 ICl3(l) A 1, 2 and 3 only B 1, 2 and 4 only C 1, 3 and 4 only D 2, 3 and 4 only

5 © Hwa Chong Institution 2025 9729/01/C2 Preliminary Examination [Turn Over 9 The equation for the reduction of nitrogen monoxide is shown below. 2NO + 2H2 → N2 + 2H2O The mechanism involves the following steps. 2NO ⇌ N2O2 (fast) N2O2 + H2 → N2O + H2O (slow) N2O + H2 → N2 + H2O (fast) Which statement about the reaction is correct? A The overall order of the reaction is 4. B The units of the rate constant are mol−2 dm6 s−1. C The reaction is second order with respect to [H2]. D The reaction is zeroth order with respect to [NO]. 10 The distribution of the number of molecules with energy, E, for a reaction at two different temperatures is shown below. The letters P, Q and R refer to separate and differently shaded areas. Which expression gives the fraction of molecules that have energy greater than or equal to the activation energy at the lower temperature? A R P + R B Q + R P + R C R P D Q + R P number of molecules with energy, E energy, E activation energy T1 T2

6 © Hwa Chong Institution 2025 9729/01/C2 Preliminary Examination 11 The Haber Process is an important industrial process in which nitrogen and hydrogen are reacted to give ammonia. N2(g) + 3H2(g) ⇌ 2NH3(g) ∆H < 0 Which statement is correct? A A temperature of 250 °C is used to ensure that the rate of reaction is fast enough. B A moderately high pressure is used to ensure high yield without being too costly. C Iron is added to increase the yield because the temperature cannot be too high. D Ammonia is constantly removed from the system to increase the rate of reaction. 12 Sulfur dioxide gas is converted into sulfate ions when it is bubbled into aqueous manganate(VII) ions. MnO4−(aq) + 8H+(aq) + 5e− → Mn2+(aq) + 4H2O(l) SO2(g) + 2H2O(l) → SO42−(aq) + 4H+(aq) + 2e− Which graph shows how the pH changes as sulfur dioxide is bubbled at a constant rate into a well-stirred solution of manganate(VII) ions until its colour just fades? A B C D pH time pH time pH time pH time

7 © Hwa Chong Institution 2025 9729/01/C2 Preliminary Examination [Turn Over 13 The titration curves for two acid-base reactions are shown below. titration 1 pH volume of base added / cm3 titration 2 pH volume of base added / cm3 The working ranges of some indicators are given in the table below. indicator working range pH methyl orange 3.1 – 4.4 bromothymol blue 6.0 – 7.0 Which statement about the two titrations is correct? A Bromothymol blue may be used for titration 2. B Methyl orange may be used for titrations 1 and 2. C Both titrations involve weak acids. D Both titrations involve weak bases.

8 © Hwa Chong Institution 2025 9729/01/C2 Preliminary Examination 14 Use of the Data Booklet is relevant to this question Hydrogen peroxide deprotonates in alkaline medium to form HO2ˉ. The diagram below shows an electrochemical cell set up to measure the cell potential for the decomposition of HO 2ˉ to form OHˉ and O2 gas. Which statements are correct? 1 The voltmeter gives a reading of −0.96 V. 2 The reaction at the cathode may be given as HO2ˉ + H2O + 2eˉ → 3OHˉ. 3 The semi-permeable membrane behaves like a salt bridge in the cell. A 1 only B 1 and 3 only C 2 and 3 only D 1, 2 and 3 only 15 Use of the Data Booklet is relevant to this question. An electrolysis cell is set up with an anode made of an alloy of 75% Cu and 2