01 2024 CCKSS 4E Prelim CHEM P1

2 2 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 3 A paper chromatogram is shown in the diagram below. Which of the following statements is true? 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. 1 An experiment is carried out to determine the rate of thermal decomposition of zinc carbonate. ZnCO3 à ZnO + CO2 Which set of measuring apparatus is necessary for the experiment? A burette, gas syringe, pipette B electronic balance, gas syringe, stopwatch C electronic balance, pipette, thermometer D measuring cylinder, stopwatch, gas syringe solvent front compound A start line x compound B z y

2024 / S4 / CHEM / PRELIM / P1 [TURN OVER 3 4 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. 5 The rate of diffusion of nitrogen and ammonia gases were compared at 50 oC and 25 oC. Which would have the slowest rate of diffusion? A Nitrogen gas at 50 oC. B Nitrogen gas at 25 oC. C Ammonia gas at 50 oC. D Ammonia gas at 25 oC. 6 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

2024 / S4 / CHEM / PRELIM / P1 4 7 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 8 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

2024 / S4 / CHEM / PRELIM / P1 [TURN OVER 5 9 Silver, graphite, silver nitrate and sulfur dioxide show different physical properties. Which statement is correct? A Silver and silver nitrate can conduct electricity in water due to their free moving ions. B Graphite can conduct electricity within each layer in its structure due to free moving electrons. C Sulfur dioxide has a low boiling point as weak forces of attraction between its atoms are overcome during boiling. D Silver has high melting point due to the strong electrostatic forces of attraction between oppositely charged ions in its structure. 10 Caffeine, C8H10N4O2, is present in coffee and tea. [Ar: C, 12; H, 1; N, 14; O, 16] What is the percentage by mass of nitrogen in caffeine? A 7% B 14% C 29% D 58% 11 8 g of X2O3, an oxide of element X, contains 70 % of X. How many moles of X does 8 g X2O3 contain? A 8 3 16 2 B 8 2 16 3 C 2.4 3 16 2 D 2.4 2 16 3 x x x x

2024 / S4 / CHEM / PRELIM / P1 6 12 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% 13 The information about two indicators is given. indicator description Thymol blue • 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. Phenolphthalein • colourless when pH is less than 10 • 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 14 H, J and L are in the same period in the Periodic Table. ● The oxide of H dissolves in water to form a solution with a pH of 12.5. ● The oxide of J forms a solution with a pH less than 4.5. ● The oxide of L is soluble in both aqueous potassium hydroxide and dilute nitric acid. Which option shows the position of the elements in order of decreasing atomic number? A H, J, L B H, L, J C J, L, H D L, J, H

2024 / S4 / CHEM / PRELIM / P1 [TURN OVER 7 15 A gaseous mixture of propene, carbon dioxide, oxygen and sulfur dioxide is passed through the apparatus shown. Only one of the gases is collected. A Gas relights a glowing splint. B Gas forms a white precipitate with limewater. C Gas turns moist blue litmus paper red. D Gas decolourises purple acidified potassium manganate(VII). 16 Silver nitrate is made by reacting an excess of a powdered solid with an aqueous solution. The mixture is filtered and the filtrate crystallised. Which row identifies a powdered solid and an aqueous solution that can be used to prepare a pure sample of silver nitrate? powdered solid aqueous solution A silver zinc nitrate B silver oxide sodium nitrate C silver carbonate dilute nitric acid D silver chloride zinc nitrate 17 Which statement about transition metals is incorrect? A Only transition metals or their compounds are used as catalyst. B Transition metals form coloured compounds. C Transition metals conduct electricity due to free-moving electrons. D Transition metals have variable oxidation states. gas mixture water aqueous sodium hydroxide aqueous bromine

2024 / S4 / CHEM / PRELIM / P1 8 18 Which of the following statements regarding caesium are correct? 1 It reacts with water to form a metal oxide and hydrogen gas. 2 It reacts with dilute acid to release more heat than potassium. 3 It has a lower density than sodium. 4 It has a lower melting point than lithium. A 1 and 2 B 2 and 4 C 1, 2 and 3 D 2, 3 and 4 19 P, Q and R are elements found in Group 17 of the Periodic Table. Three reactions are carried out to determine the reactivity of P, Q and R. 1 P2 (aq) + 2R- (aq) → R2 (aq) + 2P- (aq) 2 Q2 (aq) + 2P- (aq) → no reaction 3 Q2 (aq) + 2R- (aq) → R2 (aq) + 2Q- (aq) Which statement about P, Q and R is correct? A Q is more reactive than P. B P has a darker colour than R. C Q is a stronger oxidising agent than R. D R is a gas at room temperature and pressure. 20 Which statement about the industrial production of ammonia is correct? A The production of ammonia is an exothermic reaction. B The hydrogen used is obtained from the fractional distillation of liquefied air. C 1 mole of hydrogen reacts with 3 moles of nitrogen to give 2 moles of ammonia. D Adding iron will provide an alternative pathway with higher activation energy.

2024 / S4 / CHEM / PRELIM / P1 [TURN OVER 9 21 An aqueous solution containing two salts is found. A series of tests is carried out to identify the ions present. The results are shown. test observations Add dilute nitric acid followed by aqueous lead(II) nitrate. No effervescence and white precipitate is observed. Add aqueous sodium hydroxide followed by warming. White precipitate is formed and dissolves in excess sodium hydroxide to form a colourles