2023 ESSS Chem Prelims P1

CHEMISTRY 6092/01 Paper 1 Multiple Choice Tuesday 1 hour 12 September 2023 0800 – 0900 Additional Materials: Multiple Choice Answer Sheet ___________________________________________________________________ READ THESE INSTRUCTIONS FIRST This question booklet consists of 17 printed pages including the cover page. East Spring Secondary School Towards Excellence and Success Preliminary Examination 2023 Secondary 4 Express Name: …………………………………………………………………………………….… ( ) Class: ……………… Write in soft pencil. Do not use staples, paper clips, glue or correction fluid. Write your name, class, index number on the Answer Sheet in the spaces provided. There are forty 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. 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 17. The use of an approved scientific calculation is expected, where appropriate.

2 1 The diagram below shows the setup for a chemical reaction which produces a gas. The gas is then dried and collected. What could the gas be? A sulfur dioxide B carbon dioxide C oxygen D hydrogen 2 The cooling curve below shows how the temperature of a gaseous substance changes with time as it is cooled. What is the state of the substance at 25°C? A gas-liquid mixture B liquid C liquid-solid mixture D solid

3 3 The set–up below shows how the relative rate of diffusion of gas X and Y can be determined. The water level at Z does not move. Which of the following could be gas X and gas Y? X Y A carbon monoxide carbon dioxide B ethene nitrogen C carbon dioxide sulfur dioxide D sulfur dioxide ammonia 4 When aqueous sodium hydroxide is warmed with substance R, a white precipitate that is soluble in excess sodium hydroxide was formed. Then, when a piece of aluminium foil is added to the mixture, a colourless and pungent gas is evolved. The gas turns moist red litmus paper blue. Which of the following could substance R be? A ammonium chloride B ammonium nitrate C calcium chloride D zinc nitrate 5 Which statement about methods of purification and analysis is correct? A A liquid that boils over a range of temperatures may still be 100% pure. B An insoluble substance may be purified using simple distillation. C Chromatography may only be used to separate coloured substances. D Liquid air can undergo fractional distillation, giving oxygen as one of the products.

4 6 A sample was analysed by paper chromatography. The first experiment was conducted using water as a solvent, and the second experiment was done using ethanol as a solvent. The results of the two experiments are shown in the diagram below. What conclusion can be drawn based on these results? A Substance Y is more soluble in water than in ethanol. B Substance X is more soluble in ethanol than substance Y. C The Rf value of substance X is greater when water is a solvent instead of ethanol. D The Rf value of substance Y smaller when ethanol is a solvent instead of water. 7 The table below shows information about the elements argon, Ar, and calcium, Ca. element Ar Ca proton number 18 20 nucleon number 40 40 Which of the following statements about the elements is correct? A A Ca2+ ion has the same number of electrons as an atom of Ar. B A Ca2+ ion has the same number of protons as an atom of Ar. C An atom of Ar has two more electrons than an atom of Ca. D An atom of Ca has the same number of neutrons as an atom of Ar.

5 8 The diagram represents an isotope of an atom of element X. Which one of the following correctly describes the particles of the other isotope of the element? number of protons number of neutrons number of electrons A 5 6 5 B 5 5 5 C 6 5 5 D 11 12 11 9 The ion AH4+ can be represented by the ‘dot and cross’ diagram shown. Which Group of the Periodic Table does element A belong to? A I B III C IV D V 5p 6n

6 10 Nanotube is an allotrope of carbon. These carbon nanotubes are molecular-scale tubes of carbon arranged similarly to the layers in graphite. Which row about the physical properties of carbon nanotubes is correct? melting point electrical conductivity A high good B high poor C low good D low poor 11 Iron is a metal. The structure of iron is described as a lattice of positive ions in a ‘sea of electrons’. Which statements about iron are correct? 1 Iron conducts electricity because the electrons are free to move. 2 Iron conducts heat in solid state because the positive ions are free to move. 3 Iron ions are held together because of their attraction for each other. 4 Iron has a high melting point due to the strong covalent bonds. A 1, 2 and 3 B 2, 3 and 4 C 1 and 3 only D 1 only 12 Hydrogen peroxide decomposes to form water and oxygen as shown in the equation below. 2H2O2 (l) → 2H2O (l) + O2 (g) When 24.8 g of impure hydrogen peroxide decomposes, 3.7 dm3 of oxygen gas was collected. What is the percentage purity of hydrogen peroxide? A 28.2% B 42.3% C 56.4% D 84.6%

7 13 In a volumetric experiment, 25.0 cm3 of 0.100 mol/dm3 sodium hydroxide reacts exactly with 20.0 cm3 of sulfuric acid. 2NaOH + H2SO4 → Na2SO4 + 2H2O What is the concentration of sulfuric acid used? A 0.0625 mol/dm3 B 0.0800 mol/dm3 C 0.125 mol/dm3 D 0.250 mol/dm3 14 Which compound contains the lowest percentage of sulfur by mass? A SO2 B H2SO4 C Na2S D MgS 15 Which product is formed at the anode when molten zinc chloride is electrolysed? A chloride ions B chlorine molecules C zinc ions D zinc atoms 16 A student wants to electroplate an iron spoon with silver only. Which of the following set ups should she use to carry out the task successfully? anode cathode electrolyte A iron spoon silver copper(II) sulfate solution B silver iron spoon copper(II) sulfate solution C iron spoon silver silver nitrate solution D silver iron spoon silver nitrate solution 17 Hydrogen reacts with chlorine according to the equation below. H2 + Cl2 → 2 HCl ΔH = −184 kJ H–H Cl–Cl bond energy in kJ/mol 436 242 What is the H–Cl bond energy in kJ/mol? A 339 B 431 C 678 D 862

8 18 The energy profile diagram for both the catalysed and uncatalysed reactions in the production of ammonia is shown below. What is the activation energy for the formation of ammonia in the presence of a catalyst? 19 A student investigates the rate of reaction between marble chips and excess hydrochloric acid. The loss in mass of the reaction flask is measured. The graph shows the results of two experiments, P and Q. Which change explains the difference between graph P and Q? A A catalyst was added in P. B A higher temperature was used in P. C Bigger marble chips were used in Q. D Hydrochloric acid was more concentrated in Q.

9 20 The table below shows the colour changes when a few drops of aqueous potassium iodide and acidified aqueous potassium manganate(VII) were added separately into four different solutions. solution potassium iodide potassium manganate (VII) 1 colourless to brown purple to colourless 2 colourless to brown no change 3 no change purple to colourless 4 no change no change Which solutions