2025 H1 Chem 8873 Prelim P1 QP CJC

1 CHEMISTRY 8873/01 Paper 1 Multiple Choice 18 September 2025 1 hour Additional Materials: Multiple Choice Answer Sheet Data Booklet READ THESE INSTRUCTIONS FIRST Write your name, HT group and NRIC/FIN number on the Answer Sheet in the spaces provided. Write in soft pencil. Do not use staples, paper clips, glue or correction fluid. 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 10 printed pages Catholic Junior College JC 2 Preliminary Examinations Higher 1

2 8873/01/CJC JC2 Preliminary Examinations 2025 For each question there are four possible answers, A, B, C and D. Choose the one you consider to be correct. 1 Use of the Data Booklet is relevant to this question. Which of the following contains 1 mole of the stated particle? A gold atoms in 79 g of solid gold B aqueous H+ ions in 10 dm3 of 0.10 mol dm-3 of H2SO4 solution C hydrogen atoms in 6 dm3 of methane gas at r.t.p. D chlorine molecules in 22.4 dm3 of chlorine gas at r.t.p. 2 Carbon disulphide vapour was burnt in oxygen according to the equation: CS2 (g) + 3O2 (g) → CO2 (g) + 2SO2 (g) A fixed amount of carbon disulphide was completely burnt in 100 cm3 of oxygen. Upon cooling, the mixture of gases was treated with an excess of aqueous sodium hydroxide and the volume of gas reduced by 30 cm3. All measurements were made at the same temperature and pressure. What was the final volume of gas left? A 10 cm3 B 30 cm3 C 40 cm3 D 70 cm3 3 Element X can exist in a few oxidation states. It was found that 0.01 mol of X2+ requires 0.004 mol of acidified potassium manganate (VII), KMnO4 for complete reaction. What is the final oxidation state of X in the above reaction? A +4 B +3 C 0 D −1 4 Use of the Data Booklet is relevant to this question. Which of the following has more neutrons than electrons and more electrons than protons? A 37Cl– B 48Ti4+ C 79Br+ D 32S2‒

3 8873/01/CJC JC2 Preliminary Examinations 2025 [Turn over 5 What is the electronic configuration of Fe3+ ion? A 1s2 2s2 2p6 3s2 3p6 3d5 B 1s2 2s2 2p6 3s2 3p6 3d3 4s2 C 1s2 2s2 2p6 3s2 3p6 3d6 4s2 D 1s2 2s2 2p6 3s2 3p6 3d10 4s1 6 The successive ionisation energies (IE) of element X are given below: IE/ kJ mol–1 1st 2nd 3rd 4th 5th 6th 7th 8th X 550 1065 4138 5500 6910 8760 10230 11800 What is the likely formula of the compound that is formed when X reacts with fluorine? A XF B XF2 C X2F D X2F3 7 In which pair of molecules is the bond angle in the first molecule smaller than that in the second molecule? A BF3 and PH3 B BeCl2 and H2S C SO3 and BCl3 D F2O and SO2 8 Which of the following correctly describes the dominant forces of attraction between two of the same compounds shown below? compound dominant forces of attraction A covalent bonds B hydrogen bonding C ionic interaction D permanent dipole – permanent dipole

4 8873/01/CJC JC2 Preliminary Examinations 2025 9 Which statements help to explain the fact that magnesium has a higher melting point than sodium? 1 Magnesium ions have more protons than sodium ions. 2 Magnesium ions have a greater charge than sodium ions. 3 Magnesium ions have a smaller ionic radius than sodium ions. A 1, 2 and 3 B 2 and 3 C 2 only D 1 only 10 Which of the following sets of substances consists of simple molecular structure, giant ionic structure and giant covalent structure? A SiCl4, MgCl2, C(graphite) B AlF3, MgCl2, C(graphite) C MgCl2, SO2, SiCl4 D Al2O3, Cu, PCl5 11 Which of the following shows the correct trend for Period 3 elements? A B C D electronegativity Na Mg Al Si P S Cl boiling point Na Mg Al Si P S Cl electrical conductivity Na Mg Al Si P S Cl Ionic radius Na Mg Al Si P S Cl

5 8873/01/CJC JC2 Preliminary Examinations 2025 [Turn over 12 The chloride of an element R of the third period is a solid at room temperature which dissolves in water to form a slightly acidic solution of pH 6.5. Which group of the periodic table does R belong to? A 1 B 2 C 13 D 14 13 Which statements are true about the elements in Group 1 of the Periodic Table? 1 They are oxidising agents. 2 Their electronegativities decrease down the Group. 3 Their ionic radii increase down the Group. A 1, 2 and 3 B 2 and 3 C 2 only D 1 only 14 Which equation correctly shows the standard enthalpy change of formation of water? A 2 H(g) + O(g) → H2O(l) B H2(g) + 1 2 O2(g) → H2O(g) C H2(g) + 1 2 O2 (g) → H2O(l) D H+(aq) + OH-(aq) → H2O(l) 15 The table shows the enthalpy change of neutralisation, Hn, for various acids and bases. acid base Hn / kJ mol‒1 hydrochloric acid potassium hydroxide ‒57.0 X potassium hydroxide ‒55.5 hydrochloric acid Y ‒53.0 nitric acid Z ‒57.4 What is the identity of X, Y and Z respectively? X Y Z A sulfuric acid aqueous ammonia calcium hydroxide B ethanoic acid aqueous ammonia calcium hydroxide C ethanoic acid potassium hydroxide aqueous ammonia D sulfuric acid potassium hydroxide aqueous ammonia

6 8873/01/CJC JC2 Preliminary Examinations 2025 16 The enthalpy changes of formation (at 298 K) of gaseous ethene (C 2H4) and gaseous ethane (C2H6) are +52 kJ mol-1 and –85 kJ mol‒1 respectively. What is the enthalpy change of reaction (at 298 K) for the process C2H4(g) + H2(g) → C2H6(g)? A +137 kJmol‒1 B +33 kJmol‒1 C –137 kJmol‒1 D –33 kJmol‒1 17 What is meant by a reaction in dynamic equilibrium? A An equilibrium that is constantly changing its position. B An equilibrium that can take place in both an open and closed system. C An equilibrium where the activation energy for the forward reaction is low. D An equilibrium where the rate of the forward and reverse reactions is the same. 18 Given the following equilibrium, 2CHClF2 (g) ⇌ CF2=CF2 (g) + 2HCl (g) ΔH = +128 kJ mol-1 Which of the following graphs best describes how the amount of CF2=CF2 (g) varies with the volume of the system at constant remperature? A B C D Amount of CF2=CF2 volume volume volume volume Amount of CF2=CF2 Amount of CF2=CF2 Amount of CF2=CF2

7 8873/01/CJC JC2 Preliminary Examinations 2025 [Turn over 19 An equilibrium is represented by the following equation: 2SO2(g) + O2(g) ⇌ 2SO3(g) H < 0 Which of the following changes would increase both the percentage yield of SO3(g) and the value of the equilibrium constant? A increasing the amount of O2(g) B decreasing the amount of O2(g) C decreasing the temperature D increasing the temperature 20 The rate of decay of a radioactive isotope (a first order reaction) was found to decrease from 200 counts per minute to 12.5 counts per minute after 48 hours. What is the half-life of this isotope? A 6 hours B 12 hours C 18 hours D 24 hours 21 The reaction A → B was found to be a zero order reaction. What would be the x and y axes that would give rise to the following graph? y-axis x-axis A rate concentration B concentration rate C concentration time D time concentration

8 8873/01/CJC JC2 Preliminary Examinations 2025 22 Which statements about the rate constant are correct? 1 The rate constant increases when a cat