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 Silve