2022 YYSS Chem Prelims P2

YUYING SECONDARY SCHOOL PRELIMINARY EXAMINATION Secondary 4 Express NAME CLASS REG. NO CHEMISTRY 6092/2 Paper 2 25 August 2022 1 hour 45 minutes Candidates answer on the Question Paper. Additional Materials: Nil Setter: Mr Danny Louis READ THESE INSTRUCTIONS FIRST Write your name, class and register number on this question booklet. Write in dark blue or black pen on both sides of the paper. You may use a pencil for any diagrams, graphs, tables or rough working. Do not use staples, paper clips, highlighters, glue or correction fluid. Section A Answer all questions in the spaces provided on the Question Paper. Section B Answer all the questions in this section in the spaces provided. The last question is in the form either/or and only one of the alternatives should be attempted. Write your answers in the spaces provided on the Question Paper. The use of an approved calculator is expected, where appropriate. 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. For Examiner’s Use Total This document consists of 19 printed pages. 80

2 Section A Answer all the questions in this section in the spaces provided. The total mark for this section is 50. A1 A list of gases is given below. A CO B NO C CH4 D SO2 E NH3 F CO2 Use the letters A, B, C, D, E and F to answer the following questions. Each letter may be used once, more than once or not at all. [ 5 ] (a) Which gas can be formed by lightning activity in the atmosphere? ___________ (b) Which is the lightest gas? ___________ (c) Which gas is formed by the decay of organic matter? ___________ (d) Which gas is used to reduce iron(III) oxide in the blast furnace? ___________ (e) Which gas turns damp red litmus paper blue? ___________ A2 A block of magnesium is burnt in oxygen to form magnesium oxide. Complete the diagrams below to show the arrangement of particles before and after the reaction. magnesium magnesium oxide [ 2 ] key oxygen atom magnesium atom

3 A3 The triple point of a pure substance is the temperature at which the substance can exist as a solid, liquid and gas at the same time. The figure below shows the triple point of carbon dioxide. (a) Mark the triple point of carbon dioxide on the figure with an ‘X’. [ 1 ] (b) A student is given carbon dioxide gas at room conditions (25 oC and 1 atm). Suggest how liquid carbon dioxide can be obtained by changing one of the conditions. [ 1 ] ___________________________________________________________ (c) Draw a ‘dot-and-cross’ diagram to show the electrons in a molecule of carbon dioxide. Show only the valence electrons in your diagram. [ 2 ] (d) What type of oxide is carbon dioxide? S