2023 JVSS Chem Prelims P1

[Turn over JURONGVILLE SECONDARY SCHOOL PRELIMINARY EXAMINATION 2023 Secondary 4 Express STUDENT NAME CLASS INDEX NUMBER CHEMISTRY 6092/01 Paper 1 Multiple Choice 28 August 2023 1 hour Additional Materials: Multiple Choice Answer Sheet READ THESE INSTRUCTIONS FIRST Write in soft pencil. Do not use staples, paper clips, highlighters, glue or correction fluid. Write your name, class and index number in the spaces at the top of this page. 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 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 15. The use of an approved scientific calculator is expected, where appropriate. DO NOT OPEN THE BOOKLET UNTIL YOU ARE TOLD TO DO SO This document consists of 15 printed pages. Setter: Mdm Ethel Chng For Examiner’s Use 40

2 1 A gas is released at point Q in the apparatus shown. Which gas changes the colour of the damp Universal Indicator paper most quickly? A chlorine B hydrogen C hydrogen chloride D oxygen 2 The reaction between aqueous sodium thiosulfate and hydrochloric acid forms a pale yellow precipitate. Na2S2O3(aq) + 2HCl(aq) → 2NaCl(aq) + H2O(l) + SO2(g) + S(s) A student follows the rate of this reaction by measuring the time taken for a cross to disappear. Besides a white tile marked with a cross, what other apparatus would be needed in the student’s experiment? A burette, pipette, stopwatch, thermometer B conical flask, electronic balance, stopwatch C conical flask, measuring cylinder, stopwatch D gas syringe, measuring cylinder, stopwatch 3 The diagram shows the steps for separating a mixture. step 1 step 2 step 3 Which mixture cannot be separated into its components by these steps? A charcoal and sugar B copper(II) sulfate and iron C magnesium nitrate and potassium carbonate D marble chips and sodium chloride point Q damp Universal Indicator paper

3 [Turn over 4 Which observation is not possible for a solid element? A It dissolves in water. B It melts at a fixed temperature. C When heated in air, it forms an oxide. D When it is electrolysed in its molten state, two products are formed. 5 An unknown solid was added to dilute hydrochloric acid. Effervescence was observed and the gas formed a white precipitate in limewater. Addition of aqueous sodium hydroxide to the resulting mixture produced a white precipitate. Upon addition of more aqueous sodium hydroxide, the white precipitate remained insoluble. What could the unknown solid be? A CaCO3 B NaHCO3 C Pb(OH)2 D ZnCO3 6 Chromium has four stable isotopes and forms ions of variable oxidation states. A particle formed from its most abundant isotope can be written as Cr3+2452. Which statements are correct about the particle shown? 1 It has 27 electrons. 2 It has 28 neutrons. 3 It has 24 protons. 4 It has same number of electron shells as Cr2453. A 1 and 3 only B 1 and 4 only C 2 and 3 only D 2 and 4 only 7 Two elements, X and Y, are in the same period of the Periodic Table. Each atom of X contributes 2 electrons to its ‘sea of electrons’, while each atom of Y shares 1 electron with another atom of Y. Which statements describe the compound formed by X and Y? 1 It conducts electricity when dissolved in water. 2 It exists as a solid at room temperature. 3 It has a crystal lattice structure similar to that of sodium chloride. 4 Its elements can be obtained by electrolysis of its aqueous solution. A 1 and 2 only B 1, 2 and 3 only C 1 and 4 only D 2 and 3 only

4 8 Allotropes of carbon include graphenes and carbon nanotubes. By rolling up a graphene sheet into a tube, a carbon nanotube is formed. Which statement is not true of a carbon nanotube? A It acts as a lubricant. B It conducts electricity. C It has a high melting point. D It is insoluble in water. 9 The following substances all contain covalent bonds. 1 carbon tetrafluoride 2 ethene 3 oxygen 4 propanol Which substances contain only single covalent bonds? A 1, 2 and 4 only B 1 and 4 only C 2 and 4 only D 3 and 4 only graphene sheet carbon nanotube rolled up

5 [Turn over 10 A mixture of carbon monoxide and oxygen is placed in a reaction vessel. A reaction occurs, forming carbon dioxide. Which diagram represents the gaseous reaction mixture in the vessel after the reaction is complete? A B C D 11 Which element contains the greatest number of atoms in 1 g? A argon B chlorine C magnesium D oxygen 12 Phosphorus pentachloride reacts with water to form phosphoric acid and hydrochloric acid. PCl5(s) + 4H2O(l) → H3PO4(aq) + 5HCl(aq) When 130 g of an impure sample of phosphorus pentachloride is reacted with an excess of water, 3 moles of hydrochloric acid are formed. What is the percentage purity of phosphorus pentachloride in the impure sample? A 32.1% B 46.2% C 76.9% D 96.2 %

6 13 Ammonium nitrate fertiliser is manufactured from ammonia by a two-stage process. stage 1 stage 2 NH3 + 2O2 → HNO3 + H2O HNO3 + NH3 → NH4NO3 What is the maximum mass of fertiliser that can be made if only 17 tonnes of ammonia is available? A 34 tonnes B 40 tonnes C 80 tonnes D 97 tonnes 14 Dilute aqueous copper(II) bromide and concentrated aqueous potassium bromide are electrolysed using inert electrodes in separate experiments. Which row shows the products of their experiments? dilute aqueous copper(II) bromide concentrated aqueous potassium bromide negative electrode positive electrode negative electrode positive electrode A bromine copper bromine potassium B copper oxygen hydrogen bromine C hydrogen bromine potassium oxygen D oxygen hydrogen oxygen hydrogen 15 The diagram shows the electrolysis of aqueous silver nitrate using silver electrodes. Which statement is correct? A Molten silver is deposited at the negative electrode. B No gas is evolved at both electrodes. C Oxygen is produced at the positive electrode. D The mass of one electrode remains unchanged. aqueous silver nitrate silver electrodes

7 [Turn over 16 In separate experiments, a cell is made to supply electrical energy. The table shows the results when rods of three metals, R, S and T are placed with a more reactive metal magnesium. rod 1 rod 2 voltmeter reading / V magnesium R 1.10 magnesium S 2.72 magnesium T 0.78 What is the correct order of reactivity for these metals? least reactive most reactive A R S T Mg B R T S Mg C S R T Mg D T R S Mg 17 The table shows the bond energies of some covalent bonds. bond bond energy in kJ/mol Cl – Cl 242 H – Cl 431 H – H 436 HCl(g) can be made from H2(g) and Cl2(g) following these steps. 1 Cl2(g) → 2Cl(g) 2 H2(g) + Cl(g) → HCl(g) + H(g) 3 H(g) + Cl2(g) → HCl(g) + Cl(g) 4 H(g) + Cl(g) → HCl(g) Which steps have a positive value of enthalpy change? A 1 and 2 only B 1, 2 and 4 only C 1 and 4 only D 3 and 4 only

8 18 Copper does not react with dilute acids, however it reacts with concentrated nitric acid to form copper(II) nitrate, nitrogen dioxide gas and water. Cu(s) + 4HNO3(aq) → Cu(NO3)2(aq) + 2NO2(g) + 2H2O(l) In one student’s experiment, this reaction proceeded at a much slower rate than it did in the other students’ experiments. Which statement could explain the slower reaction rate? A The concentration of acid used was 4.0 mol/dm3 instead of 20 mol/dm3. B The mass of metal used was 2 g instead of 1 g. C The metal pieces were much smaller. D The reaction mi