2023 CGS Chem Prelims P1

Class: Register No: Name: READ THESE INSTRUCTIONS FIRST Do not open this booklet until you are told to do so. Write in soft pencil. Do not use staples, paper clips, highlighters, glue or correction fluids. Write your name, index number and class 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 OTAS 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 14. The use of an approved scientific calculator is expected, where appropriate. This booklet consists of 14 printed pages, including the cover page. CRESCENT GIRLS’ SCHOOL SECONDARY FOUR PRELIMINARY EXAMINATION 2023 CHEMISTRY Paper 1 Multiple Choice Additional Materials: Multiple Choice Answer Sheet 6092/01 30 August 2023 1 hour

2 1 Which is the best method to collect a sample of ammonia gas? A bubble the gas into hydrochloric acid and collect with an inverted measuring cylinder B bubble the gas into water and collect with an inverted measuring cylinder C downward delivery D upward delivery 2 The apparatus can be used to show the diffusion of gases. A beaker containing gas P was placed over a porous pot containing gas Q. The resulting water levels in a U-tube are shown below. Which statement is correct? A Gas P has a larger relative molecular mass than gas Q. B Gas P has a smaller relative molecular mass than gas Q. C Gas P has the same relative molecular mass as gas Q. D It is not possible to determine which gas has a larger relative molecular mass. 3 The results of a paper chromatography experiment are shown. X is an aqueous solution of a salt of a coloured transition element. Y is an aqueous solution of a salt of a Group I element. Which row about the spot produced by X and Y is correct? larger Rf value requires use of locating agent A X X B X Y C Y X D Y Y X Y solvent front start line

3 4 Which pair of reagents could be used in a test for sulfate ions in an aqueous solution? A aqueous barium nitrate and nitric acid B aqueous barium nitrate and sulfuric acid C aqueous silver nitrate and hydrochloric acid D aqueous silver nitrate and nitric acid 5 An element Z exists as three isotopes, two of which have isotopic masses of 50 and 52. The diagram shows the mass spectrum of the element Z which shows the relative percentage abundance of two of its isotopes. What is the isotopic mass of the third isotope if the relative atomic mass of element Z is 52.033? A 51 B 53 C 54 D 55 6 Element Q has an electronic structure of 2.4. The formula of the compound formed between element Q and element R is QR2. What is the electronic structure of element R? A 2.1 B 2.5 C 2.6 D 2.7 7 The table shows some properties of four substances, A, B, C and D. Which substance has a giant molecular structure that consists of atoms held together by strong covalent bonds? melting point/oC boiling point/oC soluble in water conducts electricity when solid when molten A -120 -60 yes no no B 546 974 no yes yes C 875 1242 yes no yes D 1623 2470 no no no

4 8 How many substances below contain(s) delocalised electrons? • aqueous magnesium sulfate • deionised water • graphite • molten sodium fluoride • zinc metal A 1 B 2 C 3 D 5 9 The statements below describe elements S and T. 1. An atom of S has more protons than an atom of T. 2. An atom of T has more valence electrons than an atom of S. 3. Particles of S and T combine to form an ionic compound. Which statement can be deduced based on the statements above? A An atom of S has the same number of electron shells as an atom of T. B S forms positively charged ions. C S and T are in the same group of the Periodic Table. D An atom of S will form a covalent compound with oxygen. 10 How many pairs of electrons are shared in the molecule CH3CH2CH3? A 4 B 8 C 10 D 12 11 Which aqueous solution contains the greatest number of ions? A 1 dm3 of 0.1 mol/dm3 Al(NO3)3 B 1 dm3 of 0.2 mol/dm3 H2SO4 C 1 dm3 of 0.3 mol/dm3 MgCl2 D 1 dm3 of 0.4 mol/dm3 HCl 12 The compound called cynogen is used as a rocket propellant. Its empirical formula is CN and 1.3 g of cynogen occupied 600 cm3 at room temperature and pressure. What is its molecular formula? A CN B C2N2 C C3N2 D CN4

5 13 Zinc can be extracted from its ore, ZnO, by reducing it with coal in a blast furnace. ZnO + 2C → Zn + 2CO What is the percentage purity of the zinc ore if 1200 g of ZnO produces 250 g of zinc? A 65 250 × 1200 81 × 100 B 65 250 × 81 1200 × 100 C 250 65 × 81 1200 × 100 D 250 81 × 1200 65 × 100 14 Both hydrochloric acid and ethanoic acid have the same concentration of 0.50 mol/dm3. Which of the following will show identical results for both acids? 1. measuring the electrical conductivity of both solutions 2. testing both solutions with moist blue litmus paper 3. testing both solutions with Universal Indicator 4. titrating 25.0 cm3 of each solution with 1.0 mol/dm3 of aqueous sodium hydroxide, NaOH A 1 and 3 C 2 and 4 B 2 and 3 D 2, 3 and 4 15 The set-up shown is used to prepare aqueous copper(II) sulfate. What are the possible identities of X and Y? X Y A copper aqueous iron(II) sulfate B copper(II) carbonate aqueous sulfuric acid C copper(II) nitrate aqueous sulfuric acid D copper (II) oxide aqueous iron(II) sulfate

6 16 When a mixture of two metal oxides, M and N is added to excess aqueous sodium hydroxide, only a colourless solution is observed. Which row does not show the possible identities of oxides M and N? M N A aluminium oxide sodium oxide B calcium oxide magnesium oxide C lead(II) oxide aluminium oxide D zinc oxide lead(II) oxide 17 Which statements about the Haber Process are correct? 1. Ammonia formed is removed by condensation. 2. The source of hydrogen is from liquid air. 3. The reaction chamber is pressurised to speed up the reaction. A 1 and 2 only B 1 and 3 only C 2 and 3 only D 1, 2 and 3 18 Which underlined reagent is an oxidising agent? A CuCl2 + Mg → MgCl2 + Cu B NH3 + HCl → NH4Cl C Mg + 2HNO3 → Mg(NO3)2 + H2 D Zn + H2O → Zn(OH)2 + 2H2 19 In which reaction is substance X reduced? A Purple acidified aqueous potassium manganate(VII) decolourises when a solution of X is added. B Colourless aqueous potassium iodide turns brown when a solution of X is added. C Yellow solution of Fe3+ turns green when a solution of X is added. D Blue solution of CuSO4 turns colourless and a reddish brown solid forms when solid X is added.

7 20 In Experiment 1, 1.0 g of zinc strip was added to excess nitric acid at room temperature. The volume of gas produced was measured over a period of time. The results for Experiment 1 are plotted on a graph. The experiment is repeated with one change. The results for Experiment 2 are plotted on the same graph. Which change is made in Experiment 2? A Acid of twice the concentration and 0.5 g of zinc was used. B Acid of half the concentration and 2.0 g of zinc was used. C The temperature of the acid was increased to 35oC. D Zinc powder was used instead of zinc strips. 21 In the iodine clock reaction, hydrogen peroxide reacts with potassium iodide in the presence of dilute acid to produce iodi