QTSS Prelim 2024 Sec 4Exp Chemistry P2 [6092]_Ans

This document consists of 24 printed pages. Name: ………………………………………………….. ( ) Class: Sec 4 SG 1 / 2 Queenstown Secondary School Preliminary Examination 2024 Secondary Four Express Chemistry 6092/02 20 August 2024 Time: 1115 – 1300h Tuesday Duration: 1 hour 45 minutes Setter: Additional Materials: 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. A copy of the Periodic Table is printed on page 24. The use of an approved scientific calculator is expected, where appropriate. Examiner’s Use Section A /70 Section B /10 B9 B10 TOTAL /80

2 Queenstown Secondary School [Turn over Section A Answer all questions. A1 Use the list of substances to answer the questions. calcium hydroxide carbon monoxide copper hydrogen magnesium nitrogen nitrogen dioxide sulfur dioxide zinc oxide Each substance can be used once, more than once or not at all. Name the substance(s) which (a) is added to soil to increase the pH, calcium hydroxide [1] (b) helps prevent iron in underwater pipes from rusting, magnesium [1] (c) lead to the formation of acid rain that corrodes limestone buildings, sulfur dioxide and nitrogen dioxide [1] (d) react in a 1:3 ratio in the Haber Process to produce ammonia. nitrogen and hydrogen [1] [Total: 4]

3 Queenstown Secondary School [Turn over A2 Esters are commercially used as solvents for cosmetics, perfumes and glue. (a) Propyl ethanoate has a characteristic odour of pears and is commonly used in fragrances. A bottle of perfume containing propyl ethanoate is left opened in a laboratory and it diffused throughout the laboratory. (i) Give the names and draw the full structural formulae of the carboxylic acid and the alcohol that react to form propyl ethanoate. H O | || H – C – C – O – H | H ethanoic acid H H H | | | H – C – C – C – O – H | | | H H H propanol [2] (ii) The temperature of the laboratory is increased. Explain, in terms of collisions between reacting particles, what effect would this have on the rate of diffusion of propyl et