2023 SCGS Chem Prelims P1

CANDIDATE NAME CLASS 4 REGISTER NUMBER CENTRE NUMBER INDEX NUMBER CHEMISTRY 6092/01 PAPER 1 Multiple Choice 30 August 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 register number on the Answer Sheet in the spaces provided. There are forty questions in this paper. Answer all questions. For each question, there are four possible answers, A, B, C, 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. This question paper consists of 18 printed pages. SINGAPORE CHINESE GIRLS’ SCHOOL PRELIMINARY EXAMINATION SECONDARY FOUR

2 [Turn Over 1. When iron reacts with dilute hydrochloric acid, hydrogen is formed. Due to the presence of impurities in the iron , some hydrogen sulfide gas is also formed in the reaction . Hydrogen sulfide gas is soluble in water. Which diagram shows the apparatus suitable to prepare a pure and dry sample of hydrogen? A B C D iron and hydrochloric acid water concentrated sulfuric acid iron and hydrochloric acid water concentrated sulfuric acid iron and hydrochloric acid concentrated sulfuric acid water iron and hydrochloric acid concentrated sulfuric acid water

3 [Turn Over 2. In which state does 1 dm3 of ethene contain the most particles? A gas at 100 °C B gas at room temperature C liquid D solid 3. A student carried out an experiment using the set-up shown below to separate a mixture containing four alcohols. The table gives the boiling points of the four alcohols used. alcohol boiling point / °C butanol 117 ethanol 79 pentanol 138 propanol 97 Despite repeated attempts, the student only managed to obtain two alcohols from the mixture. Which alcohols did he fail to obtain? A butanol and ethanol B butanol and pentanol C ethanol and propanol D pentanol and propanol thermometer water condenser alcohol collected mixture of alcohols electric heater

4 [Turn Over 4. Chromatography is carried out on a mixture of three substances. The chromatogram is sprayed with a locating agent and the result is shown below. What are the possible reasons why the chromatogram shows only two spots? 1 One of the substances in the mixture is insoluble in the solvent. 2 The locating agent did not react with one of the substances in the mixture. 3 Two of the substances in the mixture have the same Rf values. 4 The Rf value of one of the substances is too small. A 1 and 2 B 1 and 4 C 2 and 3 D 3 and 4 5. Aqueous sodium thiosulfate reacts with acid to make a precipitate of sulfur. Na2S2O3(aq) + 2HCl (aq) → 2NaCl(aq) + H2O(l) + SO2(g) + S(s) A student investigates the effect of temperature on the rate of this reaction. The student: • places a piece of paper with a cross on it below the reaction mixture as shown in the diagram • measures the time taken for the cross to no longer be seen • repeats the reaction at different temperatures. Which apparatus is needed for this investigation? A electronic balance, pipette, stopwatch B electronic balance, stopwatch, thermometer C burette, gas syringe, thermometer D measuring cylinder, stopwatch, thermometer start line solvent front paper with cross 50 cm3 of aqueous sodium thiosulfate + acid

5 [Turn Over 6. Three tests are carried out on salt S. test result 1 Add dilute nitric acid to salt S. Effervescence of a colourless odourless gas. 2 To 2 cm3 of the mixture from test 1, add aqueous sodium hydroxide until no further changes is observed. Green precipitate formed . Precipitate is insoluble in excess aqueous sodium hydroxide. 3 To 2 cm3 of the mixture from test 1, add aqueous silver nitrate. No precipitate formed. What is the identity of S? A copper(II) carbonate B copper(II) chloride C iron(II) carbonate D iron(II) chloride 7. The diagram shows the electronic structure of a particle with a mass number of 40. The table shows the suggestions that three students, 1, 2 and 3, made to identify the particle. student 1 2 3 particle Ar Cl Ca2+ Which students are correct? A 1 and 2 B 1 and 3 C 2 and 3 D 1, 2 and 3 8. The electronic structures of two atoms, P and Q, are shown. P and Q combine to form a compound. What is the type of bonding in the compound and what is the formula of the compound? type of bonding formula A covalent QP B covalent Q2P C ionic QP D ionic Q2P

6 [Turn Over 9. The properties of W, X, Y and Z are shown in the table. melting point / °C boiling point / °C electrical conductivity W 1728 2230 does not conduct X 3500 4800 conducts when solid Y 120 not applicable does not conduct Z – 183 – 162 does not conduct What are correct identities of W, X, Y and Z? W X Y Z A graphite poly(ethene) silicon dioxide methane B methane graphite poly(ethene) silicon dioxide C poly(ethene) methane graphite silicon dioxide D silicon dioxide graphite poly(ethene) methane 10. An aqueous solution contains 0.01 mol of Pb2+(aq) and 0.01 mol of Cu2+(aq). Aqueous ammonia is added until in excess. After shaking, the mixture is filtered. What remains on the filter paper? A 0.01 mol of a white hydroxide and 0.01 mol of a blue hydroxide B 0.01 mol of a white hydroxide C 0.01 mol of a blue hydroxide D no solid residue 11. 2.56 g of a metal oxide, MO2, is reduced to 1.92 g of the metal, M. What is the relative atomic mass of M? A 48 B 96 C 128 D 192 12. Potassium sulfate, K2SO4, and potassium hydrogensulfate, KHSO4, can both be prepared using aqueous potassium hydroxide and sulfuric acid. 2KOH(aq) + H2SO4(aq) → K2SO4(aq) + 2H2O(l) KOH(aq) + H2SO4(aq) → KHSO4(aq) + H2O(l) 50 cm3 of 1 mol/dm3 potassium hydroxide is used each time. Which row shows the correct volumes of 1 mol/dm3 sulfuric acid required to prepare a sample of potassium sulfate and a sample of potassium hydrogensulfate? volume of sulfuric acid required to make potassium sulfate / cm3 volume of sulfuric acid required to make potassium hydrogensulfate / cm3 A 25 50 B 25 12.5 C 50 12.5 D 50 25

7 [Turn Over 13. The Haber process is a reversible reaction. N2(g) + 3H2(g) ⇌ 2NH3(g) The reaction has a 30% yield of ammonia. Which volume of ammonia gas, NH 3, measured at room temperature and pressure, is obtained by reacting 0.45 moles of hydrogen with excess nitrogen? A 2160 cm3 B 3240 cm3 C 4860 cm3 D 7200 cm3 14. Dilute aqueous solutions of potassium iodide and magnesium iodide are mixed together. A sample of the mixture is electrolysed using inert electrodes. What are the possible products at each of the electrodes? anode cathode A iodine oxygen B iodine potassium C oxygen hydrogen D oxygen magnesium 15. In an electrolysis experiment, the same quantity of charge deposited 27.0 g of silver and 4.33 g of chromium. [Ar: Ag,108; Cr, 52] What was the charge on the chromium ion? A 1+ B 2+ C 3+ D 4+ 16. The electrical energy, or voltage, of two simple cells is measured. statement 1: In cell 1,