2023 DSS Chem Prelims P1

This document consists of 18 printed pages. DUNMAN SECONDARY SCHOOL CANDIDATE NAME CLASS INDEX NUMBER PRELIMINARY EXAMINATION 2023 SECONDARY 4 EXPRESS CHEMISTRY 6092/01 Paper 1 14 September 2023 1 hour Additional Materials: Multiple Choice Answer Sheet READ THESE INSTRUCTIONS FIRST Write in soft pencil. Do not use staples, paper clips, glue or correction fluid. Write your name, class and index number on the Answer Sheet in the spaces provided unless this has been done for you. 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 separate Answer Sheet. Read the instructions on the Answer Sheet very carefully. 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 18. The use of an approved scientific calculator is expected, where appropriate.

2 6092/01/Prelim/4Exp/2023 1 When an excess dilute acid is added to a known quantity of calcium carbonate, the temperature of the mixture changes. A student investigates and measures the temperature changes when calcium carbonate fully reacts with the acid. The student is provided with a beaker and thermometer. Which additional apparatus are needed? 1 mass balance 2 measuring cylinder 3 stopwatch 4 styrofoam cup A 1, 2, 3 and 4 B 1, 2 and 4 only C 1 and 4 only D 2 and 3 only 2 A paper chromatogram is shown in the diagram below. Which statement about the paper chromatogram is correct? 1 A Compound A is heavier than B. B Compound A is more soluble in solvent than B. C The Rf value of compound A, y, is greater than compound B, x. D The solvent level is placed above the starting line. solvent front compound A compound B start line Z Y X

3 6092/01/Prelim/4Exp/2023 3 An organic solvent, hexane and aqueous sodium chloride are accidentally mixed together. Which methods of separation are needed to obtain pure samples of hexane and solid sodium chloride? A filtration followed by crystallisation B fractional distillation followed by evaporation to dryness C simple distillation followed by crystallisation D using a separating funnel followed by evaporation to dryness 4 A gas, R, has the following properties: 1 a choking smell 2 turns damp blue litmus paper red 3 decolourises purple acidified potassium manganate(VII) solution What is R? A ammonia B chlorine C nitrogen D sulfur dioxide 5 Two solutions, W and X, are tested with several reagents, and observations are shown in the table. test observation with W observation with X aqueous ammonia added green precipitate formed, turned brown upon standing white precipitate formed, soluble in excess to form a colourless solution aqueous sodium hydroxide, and aluminium foil added, then warmed no gas given off gas given off turns damp red litmus blue dilute nitric acid added, then aqueous silver nitrate yellow precipitate formed no visible reaction What are solutions W and X? W X A iron(II) chloride aluminium nitrate B iron(II) iodide zinc nitrate C iron(II) iodide aluminium nitrate D iron(III) iodide zinc nitrate

4 6092/01/Prelim/4Exp/2023 6 Which statement is correct about a solid being heated to become a liquid? A The forces of attraction between the particles decreases. B The speed of the particles decreases. C The size of the particles decreases. D The strength of the covalent bonds within each particle decreases. 7 An ion, L2-, has 18 neutrons and 18 electrons. What does its nucleus contain? A 16 protons and 16 neutrons B 16 protons and 18 neutrons C 18 protons and 16 neutrons D 20 protons and 18 neutrons 8 Cl-35 and Cl-37 are two isotopes of chlorine. Which statements are correct? 1 They have the same atomic number. 2 They have the same mass number. 3 They have the same physical properties. 4 They have the same chemical properties. A 1 and 2 only B 1 and 4 only C 2 and 3 only D 2 and 4 only

5 6092/01/Prelim/4Exp/2023 9 The table shows four elements, P, Q, R and S with their atomic numbers. element P Q R S atomic number 6 8 13 17 Which row shows the formulae of the compounds formed from the four elements? formula of ionic compound formed formula of covalent compound formed A PR2 QS2 B PS2 R2Q C R2Q3 PS4 D RS2 PQ2 10 The properties of substances W, X, Y and Z are shown in the table. W X Y Z melting point (°C) 113 3850 -77 1728 boiling point (°C) 184 4250 -33 2230 electrical conductivity no yes no no Which row correctly describes W, X, Y and Z? W X Y Z A ammonia graphite silicon dioxide iodine B ammonia iodine graphite silicon dioxide C iodine graphite ammonia silicon dioxide D iodine silicon dioxide ammonia graphite

6 6092/01/Prelim/4Exp/2023 11 Which statement(s) correctly describe(s) properties of a compound, copper(II) sulfide and a mixture of copper and sulfur? compound copper(II) sulfide mixture of copper and sulfur 1 copper and sulfur react when heated to form copper(II) sulfide copper and sulfur mix together without any heat involved 2 the ratio of copper to sulfur is always 1:1 the ratio of copper to sulfur in the mixture can vary 3 copper(II) sulfide has the properties of copper and sulfur the mixture does not have the properties of copper and sulfur A 1 only B 1 and 2 C 2 and 3 D 1, 2 and 3

7 6092/01/Prelim/4Exp/2023 12 An aqueous solution R is gradually added to an aqueous solution S. The changes in pH are shown on the graph. What are the identities of R and S? R S A aqueous ammonia ethanoic acid B aqueous ammonia hydrochloric acid C ethanoic acid sodium hydroxide D hydrochloric acid aqueous ammonia 13 The information about two indicators is given. 1 Thymol blue is red in colour when pH is less than 3. Colour changes to yellow around pH 3, and changes colour a second time to blue around pH 9. 2 Phenolphthalein is colourless when pH is less than 10, and changes colour to red at about pH 10. What would be the colour of aqueous potassium chloride solution when both indicators are added to the solution? A blue B green C orange D yellow volume of R added/ cm3 pH

8 6092/01/Prelim/4Exp/2023 14 5.0 cm3 of gaseous hydrocarbon reacts with excess oxygen to form 30.0 cm3 of carbon dioxide and 15.0 cm3 of water vapour. What is the formula of the hydrocarbon? A C2H4 B C3H6 C C6H6 D C6H10 15 An aqueous solution of sulfuric acid has a concentration of 1.0 mol/dm3. Different volumes of this sulfuric acid are added to different volumes of aqueous sodium hydroxide. The maximum temperature reached in each mixture is measured. The graph shows the results. What is the concentration of the aqueous sodium hydroxide? A 0.60 mol/dm3 B 0.75 mol/dm3 C 1.50 mol/dm3 D 3.00 mol/dm3 16 The complex ion [Co(NH3)x]3+ consists of 36% by mass of cobalt, Co. What is the value of x? A 3 B 5 C 6 D 8 maximum temperature reached/ °C volume of H2SO4/ cm3 volume of NaOH/ cm3

9 6092/01/Prelim/4Exp/2023 17 When 42.0 g of lead(II) carbonate (Mr = 267) is strongly heated, 2.5 dm3 of carbon dioxide, measured at room temperature and pressure, is produced. PbCO3 → PbO + CO2 What is the percentage yield of carbon dioxide? A 15% B 28% C 35% D 66% 18 In which process is energy released? A dissolving ammonium chloride in water B forming a hydrogen molecule from two hydrogen atoms C molecules change from closely packed to far apart D thermal decomposition of calcium carbonate 19 The equation for the combustion of methane is shown. CH4 (g) + 2O2 (g) → CO2 (g) + 2H2O (l) C-H O=O O-H C=O bond energy in kJ / mol 413 498 463 799 What is the enthalpy change of this reaction? A -802 kJ / mol B -374 kJ / mol C +374 kJ / mol D +802 kJ / mol 20 In an e