CGSS 2023 Chemistry Prelim Paper 1

CEDAR GIRLS’ SECONDARY SCHOOL Preliminary Examination 2023 Secondary Four CHEMISTRY 6092/01 Paper 1 Multiple Choice 13 Sep 2023 1 hour Additional Materials: Multiple Choice Answer Sheet READ THESE INSTRUCTIONS FIRST Write in soft pencil. Do not use staples, paper clips, highlighters, glue or correction fluid. Write your name , class and index number on the Answer Sheet in the spaces provided unless this has been done for you. 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 18. The use of an approved scientific calculator is expected, where appropriate. This document consists of 18 printed pages. [Turn over

2 1 Diagram 1 shows the paper chromatogram of substance X. Diagram 2 shows the cooling curve for substance Y. Which statement about X and Y is correct? A X is a mixture and Y is a pure substance. B X is a pure substance and Y is a mixture. C X and Y are mixtures. D X and Y are pure substances.

3 [Turn over 2 A drop of liquid bromine is placed in the bottom of a gas jar. Brown fumes of bromine vapour slowly spread through the covered gas jar. Why does this happen? A Bromine vapour is less dense than air. B Bromine molecules and the molecules in air are always moving around. C Bromine molecules are smaller than the molecules in air. D Bromine molecules move faster than the molecules in air. 3 Aqueous silver nitrate is added to aqueous barium iodide until no more precipitate forms. The precipitate is filtered off. Dilute sulfuric acid is added to the filtrate until no more precipitate is formed. The precipitate is filtered off. Which statement is correct? A Both precipitates are soluble in excess aqueous sodium hydroxide. B Both precipitates are white. C Effervescence is observed in the second experiment. D Nitric acid is present in the filtrate after the second experiment.

4 4 Which graph shows the number of electrons in the outer shell of an atom, plotted against the proton number for the first ten elements in the Periodic Table? A B C D 5 Element X reacts with nitrogen to form an ionic compound, X3N2. Which formula for compounds formed by X is correct? A XO2 B XS2 C XF2 D X2O 6 Which compound has both ionic and covalent bonds? A ammonium chloride B carbon dioxide C ethyl ethanoate D sodium sulfide

5 [Turn over 7 When a covalent liquid boils, its molecules become more widely spaced. Which property of the molecule has the most influence on the energy required to boil a covalent liquid? A The forces of attraction between the molecules B The reactivity of the molecules C The shape of the molecules D The strength of the covalent bonds in the molecules 8 124 g of phosphorus vapour has the same volume of 71 g of chlorine gas at the same temperature and pressure. What is the formula of a molecule of phosphorus? A P B P2 C P4 D P8 9 The mass of one mole of a chloride formed by a metal Y is 74.5 g. What is the formula of the chloride? A Y3Cl B Y2Cl C YCl D YCl2 10 The energy level diagram for the reaction between sodium hydroxide and hydrochloric acid is shown. The enthalpy change for one mole of water to be formed in this reaction is −54 kJ/mol. What is the energy given out when 100 cm3 of 1.0 mol/dm3 hydrochloric acid reacts with 100 cm3 of 1.0 mol/dm3 sodium hydroxide? A 0.54 kJ B 2.70 kJ C 5.40 kJ D 10.8 kJ

6 11 The isotopic composition of an element is indicated below. What is the relative atomic mass of the element? A 10.2 B 10.5 C 10.8 D 11.0 12 A solid nitrate fertiliser reacts with an alkali to produce a gas which turns damp red litmus paper blue. What is the empirical formula of this fertiliser? A NO3 B NHO3 C NH2O D N2H4O3 13 The apparatus shown below was set up to copper plate the metal spoon. The experiment did not work. What was the mistake in the apparatus? A Dilute sulfuric acid should be used as the electrolyte. B Molten copper(II) sulfate should be used as the electrolyte. C The battery should be replaced with a voltmeter. D The spoon should be the negative electrode.

7 [Turn over 14 In the commercial electrolysis of concentrated sodium chloride, the products are chlorine, hydrogen and sodium hydroxide. What is the maximum yield of chlorine and hydrogen when 58.5 kg of concentrated sodium chloride is electrolysed? yield of chlorine / kg yield of hydrogen / kg A 35.5 1 B 35.5 2 C 71 1 D 71 2 15 The diagram shows the electrolysis of molten lead( II) bromide using inert electrodes connected to an external battery. Which statement about this process is correct? A New compounds are formed. B Reddish-brown gas is formed at the cathode. C Silvery molten metal is formed at the positive terminal. D The volume of electrolyte decreases over time.

8 16 Nitric oxide, NO, and bromine vapour react together in an equilibrium reaction. 2NO (g) + Br2 (g) ⇌ 2NOBr (g) ∆H = −23.0 kJ/mol The forward reaction has an activation energy of 5.4 kJ/mol. What is the activation energy of the backward reaction? A −28.4 kJ/mol B −17.6 kJ/mol C +23.0 kJ/mol D +28.4 kJ/mol 17 The combustion of methane is exothermic. The equation is given below. CH4 + 2O2 → CO2 + 2H2O What can be deduced from this reaction? A Fewer bonds are broken than made. B Less energy is involved in breaking bonds than is involved in making bonds. C More bonds are broken than are made. D More energy is involved in breaking bonds than is involved in making bonds. 18 A student measured the temperature change when 4.0 g of potassium chloride granules was dissolved in excess water. Her calculated energy change from the reaction is +720 J. Which statement is correct? A The energy change when one mole of potassium chloride dissolves in water is +13.4 kJ. B The energy change would be greater when powdered potassium chloride is used. C The energy level of the products is lower than the reactants. D The sign of the temperature change is positive.

9 [Turn over 19 When magnesium reacts with dilute sulfuric acid, a gas is released. In a series of experiments, 0.10 g strips of magnesium are reacted separately with different concentrations of dilute sulfuric acid. In each experiment the acid is in excess. The react ion time taken for the magnesium to react completely is recorded for each experiment and shown in the graph below. Which statement is correct? 1 The approximate reaction time when 1.5 mol/dm3 of sulfuric acid is used is 10 s. 2 The rate of reaction decreases with increasing concentration. 3 The same volume of hydrogen gas is produced in each experiment. A 1 and 2 B 1 and 3 C 2 and 3 D 1, 2 and 3

10 20 Bromine is extracted from sea water. In the final stages of the process, two redox reactions take place. Step 1: Br2 (aq) + SO2 (g) + 2H2O (l) → 2HBr (aq) + H2SO4 (aq) Step 2: 2HBr (aq) + Cl2 (g) → Br2 (g) + 2HCl (aq) Which row is correct? step 1 step 2 oxidising agent reducing agent oxidising agent reducing agent A Br2 SO2 Cl2 HBr B H2O Br2 Cl2 HBr C SO2 Br2 HBr Cl2 D Br2 H2O HBr Cl2 21 In volcanic areas, the air pollution due to hydrogen sulfide causes white lead