2025 H2 Chem Prelim P1 QP CJC

1 9729/01 CJC JC2 Preliminary Examination 2025 [Turn over CANDIDATE NAME CLASS 2T CHEMISTRY 9729/01 Paper 1 Multiple Choice 18 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, class and NRIC/FIN number on the Answer Sheet in the spaces provided. 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. This document consists of 11 printed pages and 1 blank page. Catholic Junior College JC 2 Preliminary Examination Higher 2

2 9729/01 CJC JC2 Preliminary Examination 2025 1 The relative abundances of all the isotopes present in a sample of zirconium are shown. What is the relative atomic mass of zirconium calculated from these data? A 91.1 B 91.3 C 91.6 D 93.1 2 In the interhalogen compound ICl, there is a single polar covalent bond. Which of the following statement(s) helps to explain the polarity of the I–Cl covalent bond? 1 Cl is more electronegative than I. 2 The outer shell electronic configuration of both elements is s2 p6. 3 The outer shell electrons are more shielded from nuclear charge in I than they are in Cl. A 1, 2 and 3 B 1 and 2 C 1 and 3 D 1 only 3 In which pairs of compounds does the first molecule have a smaller bond angle than that in the second molecule? 1 NF3 CCl4 2 H2S H2O 3 SF6 CS2 A 1, 2 and 3 B 1 and 2 C 2 and 3 D 3 only 90 91 92 93 94 95 96 51.5 11.2 17.1 17.4 2.8 Mass of isotope relative abundance

3 9729/01 CJC JC2 Preliminary Examination 2025 [Turn over 4 The table shows the boiling point of three alcohols. boiling point / °C pentan–1–ol 138 2–methylbutan–2–ol 129 2,2–dimethylpropanol 114 What is responsible for the differences in boiling point? A different relative molecular mass B different number of carbon-carbon bonds C weaker hydrogen bonding between branched chain molecules D more extensive instantaneous dipoles –induced dipoles attractions between straight chain molecules 5 Which statements about the behaviour of Group 17 elements from chlorine to iodine are correct? A The elements become stronger oxidising agents. B The volatility of the elements decreases. C The thermal stability of the hydrogen halides increases. D The bond energy of H–X bond increases. 6 0.10 mol of an oxide of nitrogen (NxOy) is mixed with an excess of hydrogen and passed over a catalyst at a suitable temperature. The water produced in this reaction has a mass of 7.2 g. The ammonia produced requires 200 cm3 of 1.0 mol dm‒3 HCl for complete neutralisation. What is the formula of this oxide of nitrogen? A N2O B NO C NO2 D N2O4 7 Sodium thiosulfate is used in the textile industry to remove an excess of chlorine from bleaching processes by reducing it to chloride ions. One mole of thiosulfate ions, S 2O32‒, is able to remove 4 moles of chlorine, C l2, in this process. In this process, S2O32‒ is oxidised. What is the resultant sulfur-containing product in this reaction? A HSO4‒ B S4O62‒ C SO2 D S

4 9729/01 CJC JC2 Preliminary Examination 2025 8 Nitric acid is made industrially by the oxidation of ammonia. The overall equation for the process is shown. equation 1 NH3 + 2O2 → HNO3 + H2O The process happens in three stages. The equations and enthalpy changes for these stages are given. stage 1 4NH3 + 5O2 → 4NO + 6H2O ΔH = –904 kJ mol–1 stage 2 2NO + O2 → 2NO2 ΔH = –114 kJ mol–1 stage 3 4NO2 + O2 + 2H2O → 4HNO3 ΔH = –348 kJ mol–1 What is the enthalpy change of the process shown in equation 1? A –1480 kJ mol–1 B –370 kJ mol–1 C –341.5 kJ mol–1 D +82 kJ mol–1 9 A radioactive element has 2 isotopes, G and H, with half -lives of 3 days and 6 days respectively. An experiment starts with 4 times as many atoms of G as of H. Given that radioactive decay is a first-order reaction, how long will it be before the number of atoms of G left equals the number of atoms of H left? A 12 days B 15 days C 24 days D 48 days

5 9729/01 CJC JC2 Preliminary Examination 2025 [Turn over 10 The kinetics of the reaction between hydrogen peroxide and acidified iodide ions were investigated. H2O2(aq) + 2H+(aq) + 2I−(aq) → I2(aq) + 2H2O(l) The rate equation was found to be rate = k[H2O2][I−] Which of the following shows the correct labelling of the x-axis for Graph I and y-axis for Graph II? Graph I Graph II rate of reaction y x-axis for Graph I y-axis for Graph II A [I−] [H2O2][I−] B [H+] [I2] C [H2O2][I–] [H+] D [H2O2][H+] [I−] 11 The reaction between HBr and O2 is thought to occur via a multi-step mechanism: HBr + O2 → HO2Br (slow) HO2Br + HBr → 2HOBr (fast) HOBr + HBr → Br2 + H2O (fast) The overall reaction is 4HBr + O2 → 2Br2 + 2H2O. Which statement is correct? A The overall order of reaction is 3. B HO2Br is the only intermediate in the reaction. C HOBr acts as a catalyst in the reaction. D Units of the rate constant is mol–1 dm3 s–1. x time

6 9729/01 CJC JC2 Preliminary Examination 2025 12 Which of the following statements is true about the following energy profile for a catalysed reaction shown below? 1 The reaction is catalysed by a heterogeneous catalyst. 2 The enthalpy change of the reaction is E3 – E2. 3 F is the intermediate formed. 4 The second step of the reaction is the rate determining step. A 2 and 3 B 2 and 4 C 1 only D 4 only 13 Phosphine, PH3, decomposes to give phosphorus and hydrogen gas. 4PH3(g) ⇌ P4(g) + 6H2(g) ∆H > 0 The graph below shows the change in concentration of PH 3 over time until the reaction mixture reaches equilibrium at a constant temperature of 400 K. Which of the following is a possible change made at t hour? A reduction of volume of the vessel B addition of PH3 C removal of P4 D addition of a catalyst energy progress of reaction E1 E3 F E2 concentration of PH3(g) / mol dm–3 time / hour t

7 9729/01 CJC JC2 Preliminary Examination 2025 [Turn over 14 Which statement about the chemical properties of the oxides in the third period of the Periodic Table is true? A Na2O and MgO can be mixed in water to give an approximately neutral solution. B Al2O3 is soluble in both KOH and HCl. C SO3 is insoluble in water. D SiO2 forms a solution of pH 2 when dissolved in water at room temperature. 15 Which one of the following statements about the behaviour of the Group 2 elements from magnesium to barium is correct? A They become weaker reducing agents. B The electronegativity increases. C The thermal stability of the metal carbonate increases. D The enthalpy change of hydration of the ions become more exothermic. 16 The concentration of carbon dioxide in the blood is regulated by the following equilibria. CO2 + H2O ⇌ H2CO3 H2CO3 ⇌ HCO3‒ + H+ During exercise, the production of lactic acid decreases the pH of blood. Which statements about these equilibria are correct when this happens? 1 The positions of both equilibria shift left. 2 [H+] decreases.