2023 NBSS Chem Prelims P1

O NORTHBROOKS SECONDARY SCHOOL Preliminary Examination 2023 Secondary 4 Express CANDIDATE NAME CLASS INDEX NUMBER CHEMISTRY 6092/01 Paper 1 Select a time zone. 15 September 2023 1 hour Additional Materials: Multiple Choice Answer Sheet READ THESE INSTRUCTIONS FIRST Write your name, class and index number on all the work you hand in. Write in soft pencil. Do not use staples, paper clips, highlighters, glue or correction fluid/tape. There are forty questions on this paper. Answer all questions. For each question there are four possible answers A, B, C and D. Choose the one you consider correct and record your choice in soft pencil on the Multiple Choice Answer Sheet. Each correct answer will score one mark. A mark will not be deducted for a wrong answer. Any rough working should be done in this booklet. A copy of the Periodic Table is printed on page 16. The use of an approved scientific calculator is expected, where appropriate. DO NOT TURN THE PAGE UNTIL YOU ARE TOLD TO DO SO. This document consists of 16 printed pages. Setter: Miss Agnes Mok

2 Use the following information to answer Questions 1 and 2. When solid hydrated barium hydroxide is added to a known quantity of solid ammonium chloride, the temperature of the mixture decreases. The chemical reaction is represented by the balanced chemical equation shown below. Ba(OH)2.8H2O (s) + 2NH4Cl (s) → 2NH3 (g) + 10H2O (l) + BaCl2 (s) 1 An experiment is designed to measure the temperature change when all the solid hydrated barium hydroxide reacts with the ammonium chloride. The following pieces of apparatus are available. 1 gas syringe 2 stopwatch 3 electronic mass balance 4 Styrofoam cup Other than a thermometer, which piece(s) of apparatus is(are) needed for this experiment? A 1, 2 and 3 only B 1 and 2 only C 3 and 4 only D 4 only 2 Which diagram shows the correct way of drying and collecting the gas produced? A B C D c gas concentrated sulfuric acid calcium oxide gas gas concentrated sulfuric acid calcium oxide water gas

3 3 Caffeine is a white solid that melts at 235 °C. A sample of impure caffeine is found to be contaminated with sugar. Propanone is an organic solvent with a low boiling point. Caffeine and sugar have different solubilities in water and propanone. substance solubility in water solubility in propanone caffeine moderate high sugar high insoluble The following steps could be carried out to obtain pure caffeine from a mixture of caffeine and sugar. I add excess water II add excess propanone III cool and crystallise IV filter the mixture V heat the filtrate In what order should the steps be carried out? A I, IV, III and V B I, IV, V and III C II, IV, III and V D II,