2023 ZHSS Chem Prelims P1

1 [Turn Over ZHONGHUA SECONDARY SCHOOL PRELIMINARY EXAMINATION 2023 SECONDARY 4 EXPRESS Candidate’s Name Class Register Number 4E CHEMISTRY 6092/01 25 Aug 2023 1 hour Additional Materials: OTAS READ THESE INSTRUCTIONS FIRST Write in soft pencil. Do not use staples, paper clips, highlighters, glue or correction fluid. Write your name, index number and class on the OTAS 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 OTAS. Read the instructions on the OTAS 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 16. This document consists of 16 printed pages.

1 A student measured the rate of reaction between calcium carbonate and dilute hydrochloric acid. A graph showing the volume of gas produced against time is shown. Which apparatus was used to measure the variables shown on the graph? A burette and stopwatch B electronic balance and burette C electronic balance and gas syringe D gas syringe and stopwatch 2 The diagram below shows the apparatus used to obtain the gas carbon monoxide. What is the main purpose of solution W? A It is to remove carbon dioxide from the gas. B It is to remove hydrogen chloride from the gas. C It is to remove nitrogen from the gas. D It is to remove water vapour from the gas. solution W calcium carbonate water carbon monoxide lumps of charcoal dilute hydrochloric acid

3 [Turn Over 3 The diagram below shows the chromatogram of some metal ions during an investigation. Which spot corresponds to Cu2+ if it has a Rf value of 0.4? 4 Which reagent(s) can be used to distinguish between aqueous zinc nitrate and aqueous calcium chloride? 1 aqueous sodium carbonate 2 aqueous lead(II) nitrate 3 dilute sulfuric acid A 1 only B 1 and 3 C 2 and 3 D 1, 2 and 3 A B C D

5 The table shows the melting points and boiling points of some substances. substance melting point / °C boiling point / °C S T U V 8 660 -3 -185 79 1314 105 -84 Which statement on the physical state of the substance is correct? A S is a solid at 25 °C. B T is a liquid at 25 °C. C U is a gas at 100 °C. D V is a gas at 100 °C. 6 Which set of three particles have the same total number of electrons? A Cl- Br - I- B F- Ne Na+ C K+ Ca2+ Br- D Li+ Na+ K+ 7 Unknown elements X and Y form an ionic compound X2Y. What is the correct electron arrangement of the atoms X and Y? atom X atom Y A 2,1 2,6 B 2,2 2,6 C 2,2 2,7 D 2,6 2,1

5 [Turn Over 8 Silicon carbide has a similar structure to diamond. What are the advantage(s) of using a silicon carbide ceramic compound instead of steel? 1 Silicon carbide has a higher melting point. 2 Silicon carbide is more resistant to oxidation. 3 Silicon carbide is less likely to deform under compression. A 1 only B 1 and 2 only C 2 and 3 only D 1, 2 and 3 9 The diagram shows three balloons filled with different gases. Which statements about the gases in the balloons are correct? 1 The number of moles of gases in the three balloons is different. 2 The number of molecules in the three balloons is the same. 3 The mass of gases in the three balloons is different. A 1 and 2 B 1 and 3 C 2 and 3 D 1, 2 and 3 10 An oxide of titanium is used as a white pigment for paint. 32 g of this oxide was found to contain 19.2 g of titanium. What is the empirical formula of the pigment? A TiO B TiO2 C Ti2O D Ti2O3 100 cm3 of carbon dioxide 100 cm3 of nitrogen 100 cm3 of oxygen

11 The equation for the reduction of iron ore in the blast furnace is shown below. Fe2O3 + 3CO à 2Fe + 3CO2 When 60 tonnes of the iron ore was reduced, 21 tonnes of molten iron was produced. What is the percentage yield of this purification process? A 25 % B 50 % C 75 % D 100 % 12 On adding aqueous lead(II) nitrate to aqueous potassium iodide, a precipitate is immediately formed. Pb2+(aq) + 2I-(aq) à PbI2(s) A student decided to add various volumes of 1.0 mol/dm3 aqueous lead(II) nitrate to 5 cm3 of 1.0 mol/dm3 aqueous potassium iodide. Each time, she centrifuged the mixture and measured the height of the precipitate formed. Below are her results. What is the minimum volume of lead(II) nitrate that the student used in test-tube X to produce the maximum height of the precipitate? A 1.0 cm3 B 2.5 cm3 C 5.0 cm3 D 10.0 cm3

7 [Turn Over 13 216 g of silver is deposited when an electric current is passed through a solution of silver nitrate using graphite electrodes. What is the mass of magnesium formed when the same amount of current is passed through molten magnesium chloride using graphite electrodes? A 24 g B 48 g C 72 g D 96 g 14 Which pair of electrolyte and electrodes will not result in a change in the concentration of the solution during electrolysis? electrolyte electrodes A copper(II) nitrate carbon B copper(II) nitrate copper C sodium nitrate carbon D sodium nitrate copper 15 Two cells were set up as shown in the diagram. The arrows show the direction of electron flow in the external circuits. Which set of metals would give the electron flows in the directions shown? metal X metal Y metal Z A copper silver zinc B silver copper zinc C silver zinc copper D zinc copper silver dilute sulfuric acid metal X metal Y metal Y metal Z

16 Which statement is true about the formation of water shown? H2 (g) + ½ O2 (g) à H2O(g) Δ H = -244 kJ/mol A The energy content of the products is 244 kJ. B The energy content of the products is 244 kJ greater than that of the reactants. C 244 kJ of energy is given out when one mole of water is formed. D 244 kJ of energy is given out because more energy is involved in bond-breaking. 17 The rate of reaction between excess calcium carbonate and 1.0 mol/dm3 hydrochloric acid was determined by collecting the carbon dioxide gas released. How would the volume of carbon dioxide collected and the rate of reaction change if the experiment was repeated using the same mass of calcium carbonate but half the volume of hydrochloric acid which has a concentration of 2.0 mol/dm3? volume of carbon dioxide collected rate of reaction A greater faster B greater slower C remain the same faster D remain the same slower 18 Copper(II) oxide catalyses the decomposition of aqueous hydrogen peroxide to give oxygen and water. In a laboratory experiment, aqueous hydrogen peroxide was shaken with copper(II) oxide in a test-tube. What can be observed in the test-tube when the reaction was completed? A a blue solution B a black solid and a colourless liquid C a light blue precipitate and a colourless liquid D a reddish-brown solid and a colourless liquid

9 [Turn Over 19 When ammonia is converted into nitric acid on a commercial scale, the following reactions can occur. In which reaction does the greatest change in oxidation number of the nitrogen occur? A 4NH3 + 5O2 → 4NO + 6H2O B 2NO + O2 → 2NO2 C 3NO2 + H2O → 2HNO3 + NO D 4NO2 + O2 + 2H2O → 4HNO3 20 Small portions of aqueous potassium iodide and acidified aqueous potassium manganate(VII) were added to three solutions. The colour changes seen are shown in the table. solution number potassium iodide potassium manganate(VII) 1 colourless to brown