2022 CWSS Chem Prelims P1

COMMONWEALTH SECONDARY SCHOOL PRELIMINARY EXAMINATION 2022 CHEMISTRY PAPER 1 Name: _____________________________________ ( ) Class: ___________ SECONDARY FOUR EXPRESS Thurs 15 Sep 2022 6092/01 1h 0800 – 0900 h READ THESE INSTRUCTIONS FIRST Write your name, index number and class on the question paper and the OTAS sheet. Write in soft pencil. An approved scientific calculator may be used. There are forty questions in this section. Answer all questions. For each question, there are four possible answers, A, B, C or D. Choose the one you consider correct and record your choice in soft pencil on the OTAS 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 19. Name of setter: Ms Tian Yilin This paper consists of <19> printed pages including the cover page. [Turn over ���

2 1 Which option shows the correct drying agent and the corresponding gas that can be collected by the method shown in the set up? drying agent gas collected A anhydrous calcium oxide carbon dioxide B anhydrous calcium oxide hydrogen C concentrated sulfuric acid ammonia D concentrated sulfuric acid chlorine 2 Two experiments, experiments 1 and 2, are set up to demonstrate the diffusion of gases. What would happen to the water levels at P and Q in both experiments? experiment 1 experiment 2 A P is higher than Q P and Q remain the same B P is higher than Q P is lower than Q C P and Q remain the same P and Q remain the same D P and Q remain the same P is higher than Q gas in drying agent experiment 1 experiment 2 ���

3 3 The apparatus is used to separate a mixture of ethanol (boiling point 78 oC), propanol (boiling point 97 oC) and butanol (boiling point 118 oC). Which graph shows the change in concentration of ethanol in the distillation flask as the distillation proceeds? A B C D concentration of ethanol concentration of ethanol concentration of ethanol concentration of ethanol ���

4 4 Two students carried out chromatography experiments to examine a urine sample. They used the same urine sample. The chromatograms obtained by the two students are shown in the diagrams. Why are the chromatograms different? A One of the students used a larger amount of urine sample. B One of the students did not use enough solvent. C One of the students added another substance to the urine sample. D The two students used different solvents. 5 The melting and boiling points of carbon tetrachloride are -23 oC and 76 oC respectively. Which diagrams best represent the arrangement of carbon tetrachloride particles as a sample of it is cooled from 80 oC to -20 oC? arrangement at 80 oC arrangement at -20 oC A 1 2 B 4 4 C 3 3 D 4 3 solvent front ���

5 6 Which of the following contains an element, a mixture and a compound? A ozone, air, sulfur trioxide B helium, distilled water, chromium C diamond, limewater, carbon dioxide D calcium carbonate, magnesium, oxygen 7 A scientist wants to carry out a series of tests on three test-tubes of different colourless solutions which are labelled X, Y and Z. To a portion of each solution, he adds silver nitrate solution followed by dilute nitric acid. His observations are shown below. test-tube X Y Z add silver nitrate solution no change observed white ppt formed white ppt formed add dilute nitric acid no change observed effervescence white ppt remained Based on his observations, what are the possible identities of the anions present in each of the three test-tubes? test-tube X test-tube Y test-tube Z A NO3 – Br – Cl – B NO3 – CO32– Cl – C NO3 – CO32– SO42– D NH4+ Br – SO42– 8 An ion contains 8 protons, 7 neutrons and 9 electrons. What is its nucleon number? A 8 B 15 C 17 D 24 ���

6 9 An imaginary element has two isotopes: • The first isotope has 15 protons and a relative abundance of 80%. • The second isotope has 16 neutrons. If the relative atomic mass of the imaginary element is 30.2, determine the number of neutrons in the first isotope. A 8 B 15 C 17 D 24 10 The relative mass and relative charge of particles P, Q, R, S and T are shown in two diagrams. Which statement(s) is/are correct? 1 Q represents an electron. 2 R represents a hydrogen ion. 3 T represents the nucleus of a helium atom. 4 P and S represent the nuclei of isotopes. A 1 only B 3 only C 1, 2 and 4 D 2, 3 and 4 11 Which substance contains both ionic and covalent bonds? A ammonium chloride B hydrogen chloride C iron(III) oxide D phosphorus trichloride relative mass relative charge P Q R S T P Q R S T 4 3 2 1 0 +2 +1 0 -1 -2 ���

7 12 The diagram shows the structure of a covalent compound containing the element hydrogen, H, and the unknown elements X, Y and Z. How many valence electrons do each of the three elements, X, Y and Z possess? X Y Z A 4 5 6 B 4 6 5 C 4 5 1 D 5 1 4 13 24 cm3 of hydrogen burns in 10 cm3 of oxygen. Which one of the following diagrams represents the molecules that remain in the reaction vessel? (All volumes are measured at room temperature and pressure. The number of particles do not represent the actual amounts.) A B C D 14 The extraction of iron in the blast furnace yields pig iron, impure iron. A student dissolves a 3.8 g sample of pig iron with an excess of sulfuric acid. 1.58 dm3 of hydrogen gas was obtained at r.t.p. Which calculation shows the percentage purity of iron in pig iron? A 1.5824÷3.856×100 B 1.58 ×24÷3.856×100 C 3.856÷(1.58×24)×100 D 3.856÷1.5824×100 ���

8 15 0.10 mol of a compound contains 4.8 g of oxygen, 1.6 g of hydrogen and 9.6 g of carbon. What is the molecular formula of the compound? A C7H12O4 B C8H16O3 C C14H24O8 D C16H32O6 16 What is the volume of 1.0 mol/dm3 of hydrochloric acid that is required to react completely with 1.25 g of zinc carbonate? A 10 cm3 B 20 cm3 C 100 cm3 D 200 cm3 17 Ethanoic acid (CH3COOH) is an acid commonly found in vinegar. It reacts with sodium hydroxide to form the soluble salt sodium ethanoate (CH3COONa) and water. What is the ionic equation for this reaction? A H+ (aq) + OH – (aq) → H2O (l) B CH3COO – (aq) + Na+ (aq) → CH3COONa (aq) C CH3COOH (aq) + OH – (aq) → CH3COO – (aq) + H2O (l) D CH3COOH (aq) + NaOH (aq) → CH3COONa (aq) + H2O (l) 18 Which statement(s) is/are true about dilute ethanoic acid and dilute hydrochloric acid? 1 Pure ethanoic acid is a stronger acid than 0.1 mol/dm3 ethanoic acid. 2 1.0 mol/dm3 ethanoic acid is a stronger acid than 0.1 mol/dm3 ethanoic acid. 3 0.1 mol/dm3 hydrochloric acid is a stronger acid than 0.1 mol/dm3 ethanoic acid. 4 0.1 mol/dm3 hydrochloric acid is a stronger acid than 1.0 mol/dm3 ethanoic acid. A 1, 2 and 3 B 2 and 3 C 3 only D 3 and 4 ���

9 19 Which equation suggests that the underlined oxide has amphoteric properties? A K2O + H2O → 2KOH B P2O5 + 6NaOH → 2Na3PO4 + 3H2O C Cl2O + 2LiOH → 2LiClO + H2O D Ga2O3 + 2KOH → 2KGaO2 + H2O 20 An excess of substance Y was added bit by bit, with stirring to aqueous solution Z. The changes in the pH of the mixture is shown in the graph. What could substance Y and Z be? substance Y substance Z A potassium oxide sulfuric acid B magnesium oxide ethanoic acid C calcium oxide ethanoic acid D zinc oxide sulfuric acid 21 Which statement describes what happens in a hydrogen fuel cell? A Electricity is used to produced water. B Electricity and water are produced. C Hydrogen is burnt to form steam. D Oxygen is produced. ���

10 22 A student carried out an experiment inv