2022 SCGS Chem Prelims P1

CANDIDATE NAME CLASS 4 REGISTER NUMBER CENTRE NUMBER INDEX NUMBER Chemistry Paper 1 Theory Additional Materials: Multiple Choice Answer Sheet 6092/01 1 hour READ THESE INSTRUCTIONS FIRST Write in soft pencil. Do not use staples, paper clips, glue or correction tape/fluid. Write your name, class and index number on the Question Paper and 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 15. The use of an approved scientific calculator is expected, where appropriate. This question paper consists of 15 printed pages and 1 blank page. SINGAPORE CHINESE GIRLS’ SCHOOL Preliminary Examination Secondary Four Wednesday 31 August 2022 ���

2 1. A gas Y, is less dense than air, very soluble in water and is alkaline. Which method is used to collect a dry sample of the gas? 2. The following measurements are made on a sample pure water: its boiling point, its freezing point, and its pH. Sodium chloride is now dissolved in the water and the measurements repeated. How do the measurements change? boiling point freezing point pH A higher lower no change B higher higher increases C lower higher no change D lower lower decreases concentrated sulfuric acid ���

3 4. A particle contains 31 protons, 40 neutrons and 28 electrons. Which symbol is correct for this particle? A 𝑁𝑁𝑁𝑁3+ 28 59 B 𝐺𝐺𝐺𝐺3+ 31 71 C 𝐺𝐺𝐺𝐺31 70 D 𝑁𝑁𝑁𝑁3− 28 59 5. How many electrons in total are shared between the atoms in a molecule of ethene, C2H4, and in a molecule of water, H2O? ethene water A 6 2 B 10 4 C 12 4 D 14 8 3. The apparatus can be used to show the diffusion of gases. Two beakers containing gas P were placed over two porous pots containing gases Q and R respectively. The results are shown below. What is the correct order of the relative molecular mass of gases P, Q and R? Lowest Mr Highest Mr A R P Q B R Q P C Q P R D P Q R beaker beaker ���

4 6. Which element forms a positive ion with the same electronic configuration as an atom of neon? A chlorine B magnesium C lithium D oxygen 7. X, Y and Z are 3 different elements in the Periodic Table. The “dot and cross” diagram of the compound formed from X, Y and Z is shown below. Only the valence electrons are shown. Which statements are correct? I Element Y could be lithium. II Element X belongs to Group VII of the Periodic Table. III Elements X and Z are bonded together by covalent bonds. IV There are more electrons than protons in ZX2 – . A I and II only B III and IV only C I, III and IV only D II, III and IV only ���

5 8. Substance X has a high melting point. It is insoluble in water and organic solvents. It is used as a lubricant and is a conductor of electricity. What is X? A copper B graphite C potassium chloride D hydrogen chloride 9. What is the ionic equation, including state symbols for the reaction between zinc carbonate and hydrochloric acid? A ZnCO 3(s) + 2H+(aq) → Zn2+(aq) + H2O(l) + CO2(g) B CO32-(aq) + 2H+(aq) → H2O(l) + CO2(g) C Zn2CO3(s) + 2H+(aq) → 2Zn+(s) + H2O(l) + CO2(g) D Zn2+(aq) + CO32-(aq) + 2H+(aq) → Zn(s) + H2O(l) + CO2(g) 10. Which quantity contains the least number of atoms? A 0.6 moles of oxygen gas B 0.75 moles of lithium C 0.25 moles of ammonia D 0.25 moles of methane 11. Brass is a mixture of copper and zinc. A sample of brass has a mass of 24.0 g. When reacted with excess dilute sulfuric acid, 1.85 dm3 of hydrogen was collected. What is the percentage of copper in the sample of brass? A 20.9% B 41.8 % C 58.2 % D 79.1 % 12. In leaded petrol there is an additive composed of lead, carbon and hydrogen only. This compound contains 29.7 % carbon and 6.19 % hydrogen by mass. What is the value of x in the empirical formula PbC8HX? A 5 B 6 C 16 D 20 ���

6 13. How much sulfuric acid is required to neutralize 100 cm3 of 1.0 mol/dm3 sodium hydroxide? A 50 cm3 of 0.5 mol/dm3 sulfuric acid B 100 cm3 of 1.0 mol/dm3 sulfuric acid C 50 cm3 of 1.0 mol/dm3 sulfuric acid D 100 cm3 of 2.0 mol/dm3 sulfuric acid 14. In an experiment, 1 cm3 of gaseous hydrocarbon X required 4 cm3 of oxygen for complete combustion to produce 3 cm3 of carbon dioxide. All gas volumes are measured at room temperature and pressure. Which formula represents X? A C 2H4 B C3H4 C C3H8 D C4H8 15. Solid Y was added bit by bit with stirring to an aqueous solution of Z. The changes in pH of the mixture are shown in the graph. Identify Y and Z. Y Z A soluble metal oxide hydrochloric acid B soluble metal oxide ethanoic acid C insoluble metal oxide nitric acid D insoluble metal oxide aqueous ammonia mass of solid Y added/g ���

7 16. A precipitate of lead(II) hydroxide dissolves in aqueous sodium hydroxide to form a colourless solution. Which property of lead(II) hydroxide can be deduced from the reaction? A Lead(II) hydroxide is a reducing agent. B Lead(II) hydroxide is basic. C Lead(II) hydroxide is soluble in water. D Lead(II) hydroxide is amphoteric. 17. The table below shows the properties of five salts, and how they can be prepared. Which one is magnesium bromide? colour solubility in water methods to prepare salt A white soluble insoluble base and acid B brown soluble titration C white insoluble precipitation D brown insoluble metal and acid 18. Which is a property of the hydroxide ion? A It combines with hydrogen to form water. B It readily breaks down into hydrogen ions and oxide ions. C It is formed when ammonia dissolves in water. D It turns methyl orange red. 19. Which statements about sulfuric acid are correct? I A blue precipitate is formed when copper(II) hydroxide is added. II 1.0 mol of sulfuric acid contains 2.0 mol of hydrogen ions. III Sulfuric acid turns Universal Indicator yellow. IV Effervescence of a colourless gas is seen when calcium is added. A I and III B II and III C I and IV D II and IV ���

8 20. Which substances would react with copper? I Dilute hydrochloric acid II Oxygen III Aqueous silver nitrate IV Cold water A I and II only C III and IV only B II and III only D All of the above 21. Which substance could be zinc? conducts electricity state of product formed when heated with oxygen when solid when liquid A   solid B ×  no reaction C  × solid D × × gas 22. Metal M will displace iron from aqueous iron(II) sulfate solution but not calcium from calcium nitrate. M is extracted from its oxide by electrolysis. M reacts with water. What could M be? A magnesium B zinc C sodium D aluminium 23. Magnesium, on the left of Period 3 of the Periodic Table, is more metallic than chlorine on the right of this Period. This is because magnesium has A fewer electrons. B fewer protons.