Copy of KCPSS 2024 4E Chem Prelim P2

[Turn Over KUO CHUAN PRESBYTERIAN SECONDARY SCHOOL 2024 PRELIMINARY EXAMINATION Secondary 4 Express NAME CLASS REG. NO CHEMISTRY 6092 / 02 Paper 2 22 August 2024 Setter: Ms Koh Li Eng 1 hour 45 minutes READ THESE INSTRUCTIONS FIRST Write your name, class and register number on all the work you hand in. Write in dark blue or black pen. You may use a 2B pencil for any diagrams, graphs or rough working. 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 24. The use of an approved scientific calculator is expected, where appropriate. FOR EXAMINER’S USE Section A 70 Section B 10 Total 80 This document consists of 23 printed page and 1 blank page.

2 KCPSS 2024/Sec 4Exp Prelim Chem P2 [Turn Over Section A Answer all questions. 1 Fig. 1.1 shows part of the Periodic Table with some elements. Fig. 1.1 Use the symbols of the elements from Fig. 1.1 to answer the questions. Each element may be used once, more than once or not at all. (a) Which element is inert? ...................................................................................................................... [1] (b) Which elements have an atomic mass of 40? ...................................................................................................................... [1] (c) Which elements exist as a black solid? ...................................................................................................................... [1] (d) Which element forms a carbonate that is the most thermally stable? ...................................................................................................................... [1] (e) Which elements are used to make brass? ...................................................................................................................... [1] (f) Which elements can be used as electrodes in the electrolysis of water? ...................................................................................................................... [1] [Total: 6] H Br Cl At Zn Ca Fe C Pt Ar Na Cu

3 KCPSS 2024/Sec 4Exp Prelim Chem P2 [Turn Over 2 Complete the table to name the most appropriate separation technique that can be used to obtain the substance underlined in the mixture. mixture separation technique ammonium chloride + sodium chloride water + lead(II) sulfate methanol + glucose solution [3] [Total: 3] 3 An experiment was carried out to investigate the rate of reaction between magnesium and dilute nitric acid using the apparatus shown in Fig. 3.1. Mg (s) + 2HNO3 (aq)  Mg(NO3)2 (aq) + H2 (g) Fig. 3.1 (a) Complete Fig. 3.1 by filling in the empty boxes to identify the apparatus. [2] water bath at 40 °C reaction mixture

4 KCPSS 2024/Sec 4Exp Prelim Chem P2 [Turn Over (b) 2.0 g of magnesium was added to 100 cm3 of 1.5 mol/dm3 of dilute nitric acid. Show that magnesium is used in excess in this reaction. [3] [Total: 5]

5 KCPSS 2024/Sec 4Exp Prelim Chem P2 [Turn Over 4 The relative abundance of isotopes can be determined experimentally using a technique called mass spectrometry. Fig. 4.1 shows t he mass spectrum of copper isotopes and their respective natural abundance. atomic mass units Fig. 4.1 (a) Based on the information, calculate the relative atomic mass of copper. Show your workings clearly and give your answer to the nearest whole number. [2] (b) Copper is a typical transition element with many of its compounds having colours. An example is copper(II) chloride solution, CuCl2, which is green-blue in colour. (i) Complete Fig. 4.2 with the expected observations when CuCl2 undergoes the different reactions. CuCl2 add dilute HNO3, add NH3(aq) dropwise, followed by AgNO3(aq) followed by excess NH3(aq) o bservations observation Fig. 4.2 [3] 69.15% 30.85% 62 63 64 65 66 67

6 KCPSS 2024/Sec 4Exp Prelim Chem P2 [Turn Over (ii) Name the type of reaction that occurred between CuCl2 and AgNO3. ............................................................................................................ [1] (iii) Under suitable conditions, CuCl2 can be converted into a compound X which is pale green in colour. The composition of X by mass is Cu, 21.5%, F, 38.7%, K, 39.8%. Use the information to work out the empirical formula of compound X. Show your working clearly. [3] [Total: 9]

7 KCPSS 2024/Sec 4Exp Prelim Chem P2 [Turn Over 5 Fig. 5.1 shows two set –ups that a student use d to investigate the difference in the reactions between an electrolytic cell and a simple cell. set–up A set–up B Fig. 5.1 (a) Draw arrows in Fig. 5.1 to show the flow of electrons on both set-ups clearly. [1] (b) It was observed that the zinc electrodes of both set-ups change in size. (i) State and explain the expected change s in sizes of the zinc electrodes in both set-ups. Your answer should: • describe the expected change in size in each set-up • explain why each change occurs • give half-equations for each change. .................................................................................................................... .................................................................................................................... .................................................................................................................... .................................................................................................................... .................................................................................................................... .................................................................................................................... .................................................................................................................... ............................................................................................................ [5] V zinc copper zinc copper salt bridge salt bridge ZnSO4 (aq) ZnSO4 (aq) CuSO4 (aq) CuSO4 (aq)

8 KCPSS 2024/Sec 4Exp Prelim Chem P2 [Turn Over (ii) Describe two differences, other than the change in size of the zinc electrode, in the observations between the two set-ups. .................................................................................................................... .................................................................................................................... .................................................................................................................... ............................................................................................................ [2] (c) The student would like to prepare more zinc sulfate and copper(II) sulfate for the experiments. Complete the table below to identify the starting reagents needed. Include state symbols. salt formulae of starting reagents used ZnSO4 (s) (1) ……………………… (2) H 2SO4 (aq) CuSO4 (s) (1) ……………………… (2) H 2