2024 PU2 H1 Chem Paper 1 (QP) MI

Class Adm No Candidate Name: This document consists of 13 printed pages and 1 blank page. 2024 Preliminary Exams Pre–University 2 H1 CHEMISTRY 8873/1 Paper 1 Multiple Choice 19 September 2024 1 hour Additional Materials: Multiple Choice Answer Sheet Additional Materials: Data Booklet READ THESE INSTRUCTIONS FIRST Do not turn over this question paper until you are told to do so. Write in soft pencil. Do not use staples, paper clips, glue or correction fluid. At the top of this page: Write your name, class and admission number in the spaces provided. On the Answer Sheet: Write your name, class and subject. Write your identification number and shade the corresponding bubbles. Ther 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. Marks 30 H Class Adm No

2 1 Which of the following substances contains 1 mol of the stated particles? particles substance A molecules 14.0 g of nitrogen gas B ions 1.00 mol of sodium chloride C hydrogen ions 1 dm3 of 1.00 mol dm–3 sulfuric acid D molecules 24.0 dm3 of carbon dioxide gas at room temperature and pressure 2 10 cm 3 of hydrocarbon was completely combusted in 50 cm 3 of oxygen. 40 cm3 of gas was present after cooling the mixture to room temperature. After passing the gases through sodium hydroxide, 20 cm3 of gas was remaining. What is the molecular formula of the hydrocarbon? A C2H4 B C2H6 C C4H8 D C4H10 3 In a reaction, i odine reacts with nitric acid in the mole ratio 1 : 10. The three products of this reaction are nitrogen dioxide, water and an iodine-containing product, X. What is the oxidation number of iodine in the iodine-containing product, X? A +1 B +3 C +5 D +7 4 Deuterium is an isotope of hydrogen. It has a relative mass of 2. What would be the correct number of subatomic particles present in an ion of deuterium that has a charge of 1–? number of protons number of neutrons number of electrons A 1 1 1 B 1 1 2 C 1 2 1 D 1 2 2

3 [Turn over 5 Which ion, when passed through an electric field, would be deflected the least? A 4He2+ B 6Li+ C 10B3+ D 14N3– 6 Which ion has the highest number of unpaired electrons? A Cr3+ B Fe3+ C Ni2+ D Cu2+ 7 Use of the Data Booklet is relevant to this question. Which metal has the lowest melting point? A Li B Na C Mg D Al 8 Phosphorus trichloride, PCl3, reacts with chlorine to form phosphorus pentachloride, PCl5. Which statements correctly describe the changes from PCl3 to PCl5? 1 The molecule turned from polar to non-polar. 2 The molecule turned from planar to three-dimensional. 3 The additional chlorine atoms formed dative bonds to phosphorus atom, as phosphorus atom contains energetically -accessible vacant orbitals to accommodate additional lone pairs of electrons. A 1 only B 2 only C 1 and 3 only D 2 and 3 only 9 Which statements correctly explain the trend in boiling points for the hydrogen halides from HCl to HBr to HI? HCl HBr HI boiling point / °C –85 –66 –35 1 The instantaneous dipole-induced dipole forces of attraction become stronger. 2 The permanent dipole-permanent dipole forces of attraction become stronger. 3 The bond energies become higher. A 1 only B 1 and 2 only C 1 and 3 only D 2 and 3 only

4 10 The progress of reaction for the formation of hydrogen iodide is shown. H2 + I2 ⟶ 2HI Which row about the magnitudes of energy changes is correct? energy required to break bonds energy released when bonds are formed enthalpy of the reaction A 𝒙 𝒙 + 𝒚 𝒚 B 𝒙 + 𝒚 𝒚 𝒙 C 𝒙 + 𝒚 𝒙 𝒚 D 𝒚 𝒙 + 𝒚 𝒙 11 Use of the Data Booklet is relevant to this question. The standard enthalpy change of sublimation of S(s) is +12 kJ mol–1. An energy cycle is shown. What is the average bond energy of the S–Cl bond in SCl2? A 9 kJ mol–1 B 125 kJ mol–1 C 131 kJ mol–1 D 253 kJ mol–1 energy reaction progress H2 + I2 𝒙 2HI 𝒚 S(g) + 2Cl(g) SCl2(g) S(s) + Cl2(g) SCl2(l) –50 kJ mol –1 +44 kJ mol –1

5 [Turn over 12 Use of the Data Booklet is relevant to this question. The temperature, T, of a beaker of 25.0 cm3 water was measured at regular intervals. At 2.0 minutes, 1.00 g of ammonium chloride was dissolved into the water. What is the enthalpy of dissolution of ammonium chloride? You may assume that the specific heat capacity of the solution = 4.18 J cm–3 K–1. A +11.2 kJ mol–1 B +11.6 kJ mol–1 C +14.5 kJ mol–1 D +15.1 kJ mol–1 24.0 25.0 26.0 27.0 28.0 29.0 30.0 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 T / °C time / min

6 13 The curve below shows the Boltzmann distribution for a reaction mixture. Which statement is correct? A At a higher temperature, energy E will shift to the right. B At a higher temperature, point M will shift upwards. C When a catalyst is used, energy E will shift to the left. D When a catalyst is used, point M will shift to the right. 14 In the Haber process, finely-divided iron is used as a catalyst for the formation of ammonia from hydrogen and nitrogen. N2(g) + 3H2(g) ⇌ 2NH3(g) ΔH < 0 Which statement correctly describes the mode of action of iron for the formation of ammonia? A Iron increases the reaction rate by desorbing H2 and N2 molecules. B Ammonia molecules adsorb onto the iron surface, increasing the local concentration of ammonia. C Iron forms weak forces with H 2 and N2 molecules, allowing the bonds in H 2 and N2 to be broken more easily. D Iron absorbs heat energy from the H 2 and N 2, shifting the equilibrium position right to increase the yield of ammonia. 15 Which reactions are catalysed by a catalytic converter in car exhaust? 1 2CO + O2 ⟶ 2CO2 2 N2 + 2O2 ⟶ 2NO2 3 S + O2 ⟶ SO2 A 1 only B 1 and 2 only C 2 and 3 only D 1, 2 and 3 number of molecules energy 𝑬 𝑴 molecules that have sufficient kinetic energy for effective collisions

7 [Turn over 16 When dinitrogen tetroxide, N 2O4, is warmed in a closed vessel it dissociates. The reaction eventually reaches equilibrium. N2O4(g) ⇌ 2NO2(g) Which graph shows the rate of the forward reaction from the start of the reaction until the system reaches equilibrium? A B C D 17 When a mixture of 1 mol of methane and 1 mol of steam is allowed to reach equilibrium at a given temperature, the mixture is found to contain x mol of methane. CH4(g) + H2O(g) ⇌ CO(g) + 3H2(g) What is the amount of hydrogen (in mol) present at equilibrium? A 3 – x B 3 – 3x C 3x D 3x – 3 rate of forward reaction time 0 rate of forward reaction time 0 rate of forward reaction time 0 rate of forward reaction time 0

8 18 A mixture of gases A and B was kept in a closed vessel. A(g) ⇌ 2B(g) ΔH < 0 At time t, one condition in the vessel was changed. What could be the change made to the vessel at time t? A The vessel was cooled. B The vessel was heated. C The vessel was compressed. D The vessel was expanded. 19 Which compound cannot behave as an Arrhenius base? A CH3OH