TKSS 2026 Chem Prelim P2 QP

1 Chemistry 6092/Sec 4/Prelim Exam/P2/2026 [Turn over TANJONG KATONG SECONDARY SCHOOL Preliminary Examination 2026 Secondary 4 NAME CLASS Index Number CHEMISTRY 6092/02 Paper 2 20 August 2026 1 hour 45 minutes Candidates answer on the Question Paper. No Additional Materials are required. READ THESE INSTRUCTIONS FIRST Write your name, class and index number on all the work you hand in. 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 24. The use of an approved scientific calculator is expected, where appropriate. For Examiner’s Use Section A My Predicted Grade Before doing assessment: After doing assessment: Section B Total 80 This document consists of 24 printed pages, including the cover page and 2 blank pages.

2 Chemistry 6092/Sec 4/Prelim Exam/P2/2026 Section A Answer all questions. 1 Choose from the following list of elements to answer the questions below. iron chlorine hydrogen iodine nickel sodium palladium zinc Each element can be used once, more than once, or not at all. (a) Which element forms an oxide which can react with both acids and alkalis? ……………………………………………………………………………………………… [1] (b) Which element is a catalyst in the hydrogenation of alkenes? ……………………………………………………………………………………………… [1] (c) Which element oxidises bromide ions to bromine? ……………………………………………………………………………………………… [1] (d) Which element is formed at the cathode when concentrated aqueous solution of sodium chloride is electrolysed? ……………………………………………………………………………………………… [1] (e) Which element is used to galvanise steel? ……………………………………………………………………………………………… [1] [Total: 5]

3 Chemistry 6092/Sec 4/Prelim Exam/P2/2026 [Turn over 2 Argon forms 1% of the air and is unreactive. Argon is used as a replacement for nitrogen when nitrogen is too reactive. (a) State one use of argon. …………………………………………………………………………………………………. ……………………………………………………………………………………………… [1] (b) Chlorine is very reactive. Argon is unreactive. Explain how the reactivity of these two elements are related to the arrangement of electrons in their atoms. …………………………………………………………………………………………………. …………………………………………………………………………………………………. …………………………………………………………………………………………………. ……………………………………………………………………………………………… [2] (c) An element R has two electron shells with one electron in its outer shell. (i) Put ticks (✓) in the boxes to show which statements about element R are true and which are false. true false R forms basic oxide. R forms R- ions. R loses one electron when it reacts. R is in the first period of the Periodic Table. [2] (ii) Name one element that is more reactive than element R. …………………………………………………………………………………….. [1] [Total: 6]

4 Chemistry 6092/Sec 4/Prelim Exam/P2/2026 3 A key is made from the alloy brass, made of copper and zinc. (a) Fig. 3.1 shows a diagram to represent the bonding in copper metal. (i) Complete the diagram by identifying particle X and Y. [1] Fig. 3.1 (ii) Describe what happens to particle X and particle Y in the structure when a metal conducts electricity. ………………………………………………………………………………………… …………………………………………………………………………………….. [1] particle X = ……………….. particle Y = ………………….

5 Chemistry 6092/Sec 4/Prelim Exam/P2/2026 [Turn over (b) Brass contains copper atoms and zinc atoms, as shown in Fig. 3.2. Fig. 3.2 Table 3.1 shows some information about brass. It contains some errors. Table 3.1 percentage of element in brass relative size of atom copper 56 1.0 zinc 37 1.1 (i) Describe how the information in Table 3.1 shows that there are more than two elements in brass. ………………………………………………………………………………………… …………………………………………………………………………………….. [1] (ii) Using Table 3.1, state another reason why Fig. 3.2 is not an accurate representation of atoms in brass. ………………………………………………………………………………………… …………………………………………………………………………………….. [1] (iii) Explain why is brass stronger than pure zinc or copper. ………………………………………………………………………………………… ………………………………………………………………………………………… …………………………………………………………………………………….. [2] zinc atom copper atom

6 Chemistry 6092/Sec 4/Prelim Exam/P2/2026 (c) A student investigates the reactivity of copper and zinc. The student places a zinc rod into a solution containing aqueous copper(II) ions and leaves it for 5 minutes, as shown in Fig. 3.3. Fig. 3.3 With the aid of an ionic equation, explain the changes that occurred. …………………………………………………………………………………………………. …………………………………………………………………………………………………. …………………………………………………………………………………………………. …………………………………………………………………………………………………. ……………………………………………………………………………………………… [3] (d) Explain why the electrolysis of aqueous copper( II) solution gives copper metal but the electrolysis of aqueous zinc solution does not give zinc metal. …………………………………………………………………………………………………. …………………………………………………………………………………………………. ……………………………………………………………………………………………… [1] [Total: 10] appearance at the start appearance after 5 minutes grey zinc rod blue solution containing copper(II) ions paler blue solution rod has orange coating

7 Chemistry 6092/Sec 4/Prelim Exam/P2/2026 [Turn over 4 Oxygen is a non-metal. (a) There are two main isotopes of oxygen, O16 and O.18 Table 4.1 shows information about the atomic structure of O16 . Table 4.1 O16 number of protons 8 number of neutrons 8 number of electrons 8 (i) Why do atoms of each isotope have the same number of electrons? ………………………………………………………………………………………… ……………………………………………………………………………………... [1] (ii) Complete the diagram for an O18 atom shown in Fig. 4.1. Use crosses (x) to represent electrons. Fig. 4.1 [2] (b) Oxygen can bond with magnesium or carbon. Discuss the differences between the way that the bonds are formed in MgO and CO2. …………………………………………………………………………………………………. …………………………………………………………………………………………………. …………………………………………………………………………………………………. ……………………………………………………………………………………………… [2] nucleus containing: ………………… protons ………………… neutrons

8 Chemistry 6092/Sec 4/Prelim Exam/P2/2026 num