Copy of AMKSS 2024 Chem P2

[Turn Over Candidate Name Form Class Index Number ANG MO KIO SECONDARY SCHOOL PRELIMINARY EXAMINATION 2024 SECONDARY FOUR EXPRESS CHEMISTRY 6092/02 Paper 2 22 August 2024 1 hour 45 minutes Setter: Mr Vincent Voo Candidates answer on the Question Paper. No Additional Materials are required. READ THESE INSTRUCTIONS FIRST Write your name, class and index number in the spaces provided at the top of this paper. Write in dark blue or black pen. You may use an HB pencil for any diagrams or graphs. Do not use staples, paper clips, glue or correction fluid. Section A Answer all questions. Write your answers in the spaces provided. Section B Answer one question. Write your answers in the spaces provided. The number of marks is given in brackets [ ] at the end of each question or part question. A copy of the Periodic Table is printed on page 19. The use of an approved scientific calculator is expected, where appropriate. For Examiner’s use Section A Section B TOTAL This document consists of 19 printed pages and 1 blank page.

2 AMKSS 4E Prelim Exam 6092/02/2024 Section A Answer all questions. 1 Fig 1.1 shows the arrangement of atoms in four substances, W, X, Y and Z. (a) State and explain, in terms of structure and bonding, which substance is a noble gas. ……………………………………………………………………………………………. ……………………………………………………………………………………………. ……………………………………………………………………………………………. [2] (b) State and explain, in terms of structure and bonding, which substance is carbon dioxide gas. ……………………………………………………………………………………………. ……………………………………………………………………………………………. ……………………………………………………………………………………………. [2] (c) Explain, in terms of structure and bonding, why substance W has high melting and boiling points. ……………………………………………………………………………………………. ……………………………………………………………………………………………. ……………………………………………………………………………………………. ……………………………………………………………………………………………. [2] (d) Suggest one similarity between substances, W, X, Y and Z. ……………………………………………………………………………………………. ……………………………………………………………………………………………. [1] [Total: 7]

3 AMKSS 4E Prelim Exam 6092/02/2024 [Turn Over 2 The reaction sequence below shows the formation of lead(II) sulfate from lead(II) oxide. (a) Lead(II) oxide is an amphoteric oxide. Explain what is meant by the term ‘amphoteric oxide’. ……………………………………………………………………………………………. ……………………………………………………………………………………………. [1] (b) Substance Y reacts with lead(II) oxide to form lead(II) nitrate. Suggest what is substance Y. ……………………………………………………………………………………………. [1] (c) Explain why lead(II) sulfate cannot be prepared by adding dilute sulfuric acid to lead(II) oxide directly. ……………………………………………………………………………………………. ……………………………………………………………………………………………. ……………………………………………………………………………………………. [2] [Total: 4] 3 Sodium sufite, Na2SO3 is used as a preservative in some foods, such as meat patties used in burgers. The amount of sodium sulfite in a sample of burger meat can be determined using manganate(VII) titration. The reaction is shown in the equation. In an experiment, sodium sulfite from 1 kg of meat was acidified with dilute sulfuric acid and titrated against 0.02 mol/dm3 aqueous potassium(VII) manganate, KMnO4. 30 cm3 of MnO4− was required to reach the end-point. (a) Calculate the number of moles of MnO4− used to react completely with SO32−. Number of moles of MnO4− = ……………………. mol [1]

4 AMKSS 4E Prelim Exam 6092/02/2024 (b) Calculate the number of moles of sodium sulfite present in 1 kg of meat. Number of moles of sodium sulfite = ……………………. mol [2] (c) Identify the reducing agent in the reaction. Explain your answer in terms of oxidation number. ……………………………………………………………………………………………. ……………………………………………………………………………………………. ……………………………………………………………………………………………. ……………………………………………………………………………………………. [2] [Total: 5] 4 Flerovium, symbol Fl is radioactive and has an atomic number of 114. It was first synthesised in 1998 and is classified as a metal. To make flerovium, atoms of plutonium (atomic number 94) are bombarded with ions of element X contained in a beam. The nucleus of one atom of plutonium combines with the nucleus of one atom of element X. This forms the nucleus of one atom of Flerovium. (a) Suggest the identity of element X. ……………………………………………………………………………………………. [1] (b) By referring to the Periodic Table on page 19, (i) state the period that Flerovium belongs to; ……………………………………………………………………………………. [1] (ii) predict the number of outer electrons in an atom of Flerovium. ……………………………………………………………………………………. [1] (c) Two isotopes of Flerovium, Fl−286 ad Fl−289 are discovered. Complete the table to show the number of protons, neutrons and electrons in atoms of the isotopes. isotope number of protons number of neutrons number of electrons Fl−286 Fl−289 [2]

5 AMKSS 4E Prelim Exam 6092/02/2024 [Turn Over (d) Only a few atoms of flerovium have ever been made, and they are only used in scientific study. It has been suggested that Flerovium is a typical metal. (i) Suggest one physical property of Flerovium. ……………………………………………………………………………………. [1] (ii) Suggest one chemical property of flerovium oxide. ……………………………………………………………………………………. [1] [Total: 7] 5 The Haber Process is used in the manufacturing of ammonia from nitrogen and hydrogen. The process can be demonstrated in the laboratory using the set -up shown in Fig. 5.1. The mixture of nitrogen and hydrogen is passed back and forth over the hot iron wool until there is no further reaction. The equation for the reaction is as shown. 3 H2 (g) + N2 (g) → 2 NH3 (g) Table 5.1 shows some bond energies, measured in kilojoules per mole. bond bond energy / kJ/mol N−H 391 H−H 436 N≡N 945 Table 5.1 (a) Suggest why it is important to ensure that no air is present in the apparatus shown in Fig. 5.1. ……………………………………………………………………………………………. ……………………………………………………………………………………………. [1]

6 AMKSS 4E Prelim Exam 6092/02/2024 (b) Using the bond energies given in Table 5.1, calculate the energy change, H involved in the manufacture of ammonia. Energy change, H = ……………………. kJ [2] (c) Is the chemical reaction in the Haber Process an exothermic or endothermic reaction? Explain your answer in terms of bond-breaking and bond-forming. ……………………………………………………………………………………………. ……………………………………………………………………………………………. ……………………………………………………………………………………………. [2] (d) Draw an energy profile diagram to represent the chemical reaction in the Haber Process. [3] (e) The rate of forming ammonia from nitrogen and hydrogen can be increased by adding iron catalyst as shown in Fig. 5.1. On the same energy profile diagram in (d), draw the profile of energy level for a catalysed reaction in the Haber Process. Label it as “catalysed reaction”. [1] [Total: 9]

7 AMKSS 4E Prelim Exam 6092/02/2024 [Turn Over 6 Fig. 6.1 shows an experiment that was carried out to investigate the rate of decomposition of hydrogen peroxide. A catalyst, manganese(IV) oxide, was added to a conical flask containing 50.0 cm3 of aqueou