2022 Punggol Sec Chemistry P3

EXP PUNGGOL SECONDARY SCHOOL SECONDARY 4/5 EXPRESS 2022 PRELIMINARY EXAMINATION QUESTION & ANSWER BOOKLET NAME CLASS INDEX NUMBER Science Chemistry Paper 3 5076/03 26 August 2022 1 hour 15 minutes READ THESE INSTRUCTIONS FIRST Write your class, register number and name on all the work you hand in. You may use a HB pencil for any diagrams, graphs, tables or rough working. Write in dark blue or black ink. Do not use staples, paper clips, glue or correction fluid. The use of an approved scientific calculator is expected, where appropriate. You may lose marks if you do not show your working or if you do not use appropriate units. Section A (45 marks) Answer all questions. Write your answers in the spaces provided on the question paper. Section B (20 marks) Answer any two questions. Write your answers in the spaces provided on the question paper. A copy of the Periodic Table is printed on page 14. The number of marks is given in brackets [ ] at the end of each question or part question. For Examiner’s use Parent’s Signature Section A /45 Section B /20 - - Total /65 This paper consists of 14 printed pages and 0 blank page.

2 Section A Answer all the questions in the spaces provided. 1 The diagrams show the atoms in four substances, W, X, Y and Z. W X Y Z (a) Which of the above diagram represents (i) copper wire : …………………… (ii) stainless steel wire : …………………… [2] (b) Explain why stainless steel wire is more difficult to bend than a copper wire. …………………………………………………………………………………………....… ………………………………………………………………………………………….…... ……………………………………………………………………………………………… …………………………………………………………………………………………….[2] [Total:4] 2 Iron (III) chloride, FeCl3, is formed when iron, Fe, is heated in chlorine gas. (a) Write a balanced chemical equation for this reaction. ……………………………………………………………………………………………[2] (b) State with reasons, whether iron is being oxidised or reduced or neither of these. …………………………………………………………………………………………….. …………………………………………………………………………………………….. ……………………………………………………………………………………………[2] [Total:4]

3 3 Separating atmospheric air into its constituent gases is an important process for obtaining nitrogen and oxygen. (a) (i) State the process used to separate air to obtain nitrogen and oxygen. ……………………………………………………………………………….....….[1] (ii) Describe why this process is able to separate the two gases. ………………………………………………………………………………………. …………………………………………………………………………..………….[1] (b) Describe the observation when a glowing splint is placed into a gas jar filled with oxygen. ………………………………………………………………………………………........[1] (c) Draw a ‘dot and cross’ diagram to show the bonding in a molecule of oxygen. Show