qtss comb chem prelim 2024 p4 answer

This document consists of 11 printed pages. Name: ………………………………………………….. ( ) Class: Sec 4 SG 5 / 6 Queenstown Secondary School Preliminary Examination 2024 Secondary Four Normal (Academic) Science (Chemistry) 5105/03 30 July 2024 Time: 1015 – 1130h Tuesday Papers 3 and 4: 1 hour 15 minutes Setter: 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 index number on the Answer Sheet in the spaces provided. There are twenty questions on this paper. Answer all questions. For each question there are four possible answers A, B, C and 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. Answers to Paper 3 and Paper 4 must be handed in separately. Each correct answer will score one mark. A mark will not be deducted for a wrong answer. You are advised to spend no more than 30 minutes on Paper 3. You may proceed to answer Paper 4 as soon as you have completed Paper 3. Any rough working should be done in this booklet. A copy of the Periodic Table is printed on page 11. The use of an approved scientific calculator is expected, where appropriate.

2 Queenstown Secondary School [Turn over 1 The diagrams show two methods of collecting gases. Which row gives the properties of a gas that can be collected by both methods? property 1 property 2 A insoluble in water denser than air B insoluble in water less dense than air C soluble in water denser than air D soluble in water less dense than air 2 Three separations are listed. 1 obtaining water from sodium chloride solution 2 obtaining solid copper(II) sulfate from copper(II) sulfate solution 3 obtaining sand from a mixture of sand and sodium chloride solution 1 2 3 A distillation crystallisation filtration B distillation evaporation sublimation C filtration crystallisation sublimation D filtration evaporation filtration

3 Queenstown Secondary School [Turn over 3 Samples of tinned apricots, beans, corn and tomatoes are tested for additives by using chromatography. The chromatograms are compared with those of three artificial additives, P, Q and R. The results are as follows. Which tinned food does not contain any artificial additives? A apricots B beans C corn D tomatoes 4 Substance X has a melting point of –7°C and a boiling point of 79°C. Which diagram shows the correct arrangement of particles of substance X under room conditions? [liquid at room conditions] A C B D

4 Queenstown Secondary School [Turn over 5 An atom of fluorine is represented by 𝐹9 19 . What is the electron arrangement of the fluorine atom? A 2,7 B 2,8 C 2,8,8 D 2,8,8,1 6 The atomic structures of four different particles are shown. particle number of protons number of neutrons number of electrons Al Al3+ S S2- W 13 16 16 14 14 Y 16 13 X 16 Z What are the values for W, X, Y and Z? W X Y Z A 10 16 14 16 B 13 10 16 18 C 13 16 18 10 D 14 13 18 14 7 Gallium combines with sulfur to make an ionic compound gallium sulfide. The formula of gallium sulfide is Ga2S3. Which row describes the melting point of gallium sulfide and the formulae of the ions in the compound? melting point ions present A high Ga2+ S3- B high Ga3+ S2- C low Ga2+ S3- D low Ga3+ S2-

5 Queenstown Secondary School [Turn over 8 The electronic structures of an atom of nitrogen [non-metal] and an atom of hydrogen [non-metal] are shown. Which row describes what happens to the electrons in the valence shells and the type of bonding when atoms of N and H form a compound? electrons type of bond A transferred covalent B shared covalent C transferred ionic D shared ionic 9 The diagram shows the arrangement of particles in substance Z. [alloy] Which statement is correct? A Z is hard and strong. B Z is soluble in water. C Z has a fixed melting point. D Z conducts electricity in the aqueous state.

6 Queenstown Secondary School [Turn over 10 The chemical equation below represents the reaction between barium nitrate, Ba(NO3)2, and copper(II) sulfate, CuSO4. Ba(NO3)2 (aq) + CuSO4 (aq) → BaSO4 (s) + Cu(NO3)2 (aq) What is the ionic equation that represents the above reaction? A Ba2+ (aq) + 2NO3– (aq) → Ba(NO3)2 (aq) B Ba2+ (aq) + SO42- (aq) → BaSO4 (s) C Cu2+ (aq) + 2NO3– (aq) → Cu(NO3)2 (aq) D Cu2+ (aq) + SO42- (aq) → CuSO4 (aq) 11 The diagram shows a model of a molecule. What is the relative molecular mass, Mr, of this molecule? [H3PO4 = 3(1) + 31 + 4(16) = 98] A 50 B 82 C 98 D 106 12 Why is calcium hydroxide [alkaline] added to soil [acidic due to SO2 and NO2]? A to decrease pH and neutralise acidity B to decrease pH and neutralise alkalinity C to increase pH and neutralise acidity D to increase pH and neutralise alkalinity H P O O O O H H

7 Queenstown Secondary School [Turn over 13 An amphoteric oxide was added separately to dilute hydrochloric acid and aqueous sodium hydroxide. Which of the following is correct? hydrochloric acid sodium hydroxide A salt formed no reaction B salt formed salt formed C no reaction salt formed D no reaction no reaction 14 Iodine, I, has a lower nucleon (mass) number than tellurium, Te, but is placed after it in the Periodic Table. Which statement explains why iodine is placed after tellurium in the Periodic Table? A Iodine has fewer neutrons than tellurium. B Iodine has fewer protons than tellurium. C Iodine has more neutrons than tellurium. D Iodine has more protons than tellurium. 15 Which statement about bromine and iodine is correct? A Bromine is a red-brown gas that reacts with sodium chloride solution.  liquid B Bromine is a red-brown liquid that reacts with potassium iodide solution. Br2 (l) + 2KI (aq) → 2KBr (aq) + I2 (s) C Iodine is a grey solid that reacts with potassium bromide solution.  black D Iodine is a purple vapour that reacts with sodium chloride solution.  no displacement

8 Queenstown Secondary School [Turn over 16 W, X, Y and Z are four different metals. W does not react with acids. [least reactive = easiest to extract] X reacts with steam and acids but not with cold water. [more reactive than Z] Y reacts with cold water. [most reactive = most difficult to extract] Z reacts slowly with acids but not with steam. Which row shows the ease with which the metals can be extracted from their ores? easiest to extract most difficult to extract A W X Z Y B W Z X Y C Y X Z W D Y Z X W 17 The names and molecular structure of two alkanes are shown. What is the next