Prelim Paper 1 QP ACJC H2 Chem

1 © ACJC 2025 9729/01/Prelim/2025 [Turn over Anglo-Chinese Junior College JC2 Preliminary Examination Higher 2 CHEMISTRY Paper 1 Multiple Choice Additional Materials: Multiple Choice Answer Sheet Data Booklet 9729/01 17 September 2025 1 hour READ THESE INSTRUCTIONS FIRST Write in soft pencil. Do not use staples, paper clips, glue or correction fluid. Write your name and index number on the Answer Sheet in the spaces provided unless this has been done for you. There are thirty questions in this section. 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 15 printed pages.

2 © ACJC 2025 9729/01/Prelim/2025 [Turn over 1 The most common oxidation state of americium, Am, in aqueous solution is +3. Recently, Cu3+ has been shown to quantitatively oxidise Am3+(aq) in dilute HNO3, while itself is reduced to Cu2+. In an experiment, 20.0 cm 3 of 0.0120 mol dm –3 Am3+(aq) was found to require 24.00 cm3 of 0.0300 mol dm–3 Cu3+ for complete oxidation. What is the formula of the americium-containing species formed? A Am2O22+ B AmO22+ C AmO2+ D AmO+ 2 Use of the Data Booklet is relevant to this question. The table shows the fifth, sixth, seventh, eighth, ninth and tenth ionisation energies of an element (Z ≤ 20) in the Periodic Table. 5th 6th 7th 8th 9th 10th ionisation energy / kJ mol–1 7975 9590 11343 14944 16964 48610 What can be inferred about the element from the above data? A It is in the third period of the Periodic Table. B It is in Group 2 of the Periodic Table. C It is likely to form an ionic compound when reacted with oxygen. D Its 6th and 7th electrons are removed from different subshells. 3 Particle R has a proton number n and forms a stable monoatomic ion of charge ‒1. Particle S has a proton number of ( n+2) and it forms a stable monoatomic ion which is isoelectronic with the ion of R. Which statement is correct? A Ion of S has a smaller ionic radius than ion of R. B R has a larger atomic radius than S. C Ion of S requires less energy than ion of R when an electron is removed from each particle. D Ion of R releases more energy than ion of S when an electron is added to each particle.

3 © ACJC 2025 9729/01/Prelim/2025 [Turn over 4 Which statement about the trend in the property of the halogens down the group is correct? A The electronegativity increases. B The volatility increases. C The enthalpy change of reaction with hydrogen becomes less exothermic. D The reactivity as reducing agents increases. 5 Use of the Data Booklet is relevant to this question. Which sequence is correct in terms of increasing radius? A Rb+ < Sr2+ < As3− < Se2− B Sr2+ < Rb+ < Se2− < As3− C As3− < Se2− < Sr2+ < Rb+ D Se2− < Sr2+ < Rb+ < As3− 6 Two bulbs are connected as shown in the diagram below. The bulbs are connected by a narrow tube of negligible volume. When the tap is opened, the two gases mix. The connected bulbs were then allowed to cool to room temperature. What was the final pressure, in kPa, in the connected bulbs? A 13.9 B 24.3 C 37.5 D 64.7 tap water vapour 5 dm3 100 kPa 180 oC neon 3 dm3 100 kPa 180 oC

4 © ACJC 2025 9729/01/Prelim/2025 [Turn over 7 (CH3)2S.BCl3 is a solid that is commonly used in laboratories as a convenient source of BC l3. When heated, it reversibly decomposes to (CH3)2S and BCl3. Which statement is true? A The dative bond is formed using the 2p orbitals of boron and sulfur. B (CH3)2S and BCl3 act as the Lewis acid and Lewis base respectively in the formation of (CH3)2S.BCl3. C The dative bond is from boron to sulfur. D The C-S-C bond angle decreases when the solid decomposes. 8 The compound Bi2Sr2Ca2Cu3O10 is a superconductor. In this compound, the oxidation number of bismuth is +3, strontium and calcium is +2 and oxygen is −2. What are the possible oxidation numbers of the three copper atoms in Bi2Sr2Ca2Cu3O10? A +1, +1, +2 B +1, +2, +3 C 0, +1, +3 D 0, +2, +3 9 The energy profile diagram below represents a certain three-step reaction. Which statements are correct about the above reaction? 1 E3 is the activation energy of the second step. 2 ∆H can be obtained by subtracting E2 from E1. 3 There are equal number of intermediates and transition states. A 1 only B 2 only C 1 and 3 D 2 and 3 E2 E1 E3 reactants products

5 © ACJC 2025 9729/01/Prelim/2025 [Turn over 10 4-hydroxybenzoic acid (A), 2 -hydroxybenzoic acid (B) and 3,4 -dihydroxybenzaldehyde (C) share the same molecular formula. All three compounds combust exothermically. Their standard enthalpy changes of formation are tabulated below. standard enthalpy change of formation / kJ mol—1 4-hydroxybenzoic acid −481 2-hydroxybenzoic acid −493 3,4-dihydroxybenzaldehyde −392 Which statements are correct? 1 2-hydroxybenzoic acid and 3,4-dihydroxybenzaldehyde are chain isomers. 2 The magnitude of the standard enthalpy change of combustion decreases in the order C > A > B. 3 The thermodynamic stability decreases in the order B > A > C. A 1, 2 and 3 B 1 and 2 C 1 and 3 D 2 and 3 11 A 0.483 g sample of glycine ( Mr = 75.0) was placed in a bomb calorimeter and then ignited in the presence of excess oxygen. The temperature rose by 0.54 oC. In a separate experiment using the same calorimeter, the combustion of 0.986 g of benzoic acid (Mr = 122.0) gave a temperature rise of 2.14 oC. The enthalpy change of combustion of benzoic acid is −3054 kJ mol−1. What is the enthalpy change of combustion, in kJ mol−1, of glycine? A −615 kJ mol−1 B −967 kJ mol−1 C −2423 kJ mol−1 D −3812 kJ mol−1

6 © ACJC 2025 9729/01/Prelim/2025 [Turn over 12 Ethyl formate undergoes a slow acid-catalysed hydrolysis in water. H+ HCO2CH2CH3 + H2O → HCO2H + CH3CH2OH The rate law is found to be rate = k[HCO2CH2CH3][H+] When 0.1 mol dm−3 of HCl is reacted with 0.4 mol dm−3 of ethyl formate, the half-life was found to be 62 min. Another reaction was carried out with 0.3 mol dm−3 of HCl and 0.4 mol dm−3 of ethyl formate. How long does it take for the concentration of ethyl formate to fall to 0.050 mol dm−3? A 31 min B 62 min C 93 min D 124 min 13 The decomposition of phosphorus pentachloride is reversible. PCl5(g) ⇌ PCl3(g) + Cl2(g) The rate constants of the forward and backward reactions are given as k1 and k−1 respectively. What happens to the values of k1, k−1, Kc and the equilibrium position if an inert gas is introduced into the reaction vessel at constant temperature and pressure? k1 k−1 Kc equilibrium position A unchanged unchanged unchanged unchanged B increases decreases increases shifts to right C decreases increases decreases shifts to left D unchanged unchanged unchanged shifts to right

7 © ACJC 2025 9729/01/Prelim/2025 [Turn over 14 Ammonium carbamate, NH2COONH4, undergoes thermal decomposition. NH2COONH4(s) ⇌ 2NH3(g) + CO2(g) H > 0 A vessel containing only NH 2COONH4 is heated to 250 oC. The reaction reached equilibrium at time t1. Subsequently both the temperature and volume of the vessel are decreased, and the reaction established a new equilibrium at time t2. Which statements are correct? 1 At t2, PNH3 : PCO2 is 2