2022 WSS Chem Prelims P1

Name: ( ) Class: WHITLEY SECONDARY SCHOOL A Caring and Learning Community of Leaders Perseverance * Respect * Integrity * Discipline * Empathy PRELIMINARY EXAMINATION 2022 READ THESE INSTRUCTIONS FIRST Write your name, class and index number in the spaces at the top of this page. 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 unless this has been done for you. There are forty questions. 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 15. The use of an approved scientific calculator is expected, where appropriate. This paper consists of 15 printed pages and 1 blank page SUBJECT : Chemistry (6092/01) LEVEL : Secondary 4 Express DATE : 29 August 2022 DURATION : 1 hour SETTER : Ms Ng Soo Hoon VETTERS : Ms Charlene Lye and Mr Ng Mun Leong ���

2 1 A gas turns moist blue litmus paper red, is soluble in water and is less dense than air. Which diagram shows a correct way of drying and collecting the gas? ���

3 2 A mixture of sand and sodium chloride can be separated in three steps. Step 1 is to add water to the mixture. The diagram shows Steps 2 and 3. Where is pure sodium chloride collected? 3 A gaseous mixture is made up of nitrogen, oxygen and nitrogen monoxide. Which diagram could show a pure sample of this mixture? ���

4 4 A beaker of an unknown gas Y was inverted over a porous pot containing carbon monoxide as shown. The apparatus was left for a while but the water level did not change. The gas Y could have been A ammonia. B carbon dioxide. C chlorine. D nitrogen. 5 The boiling points of some gases are given in the following table. gases boiling point /oC nitrogen xenon oxygen −196 −108 −183 A mixture of liquid oxygen, nitrogen and xenon at −200 oC was heated up by 15 oC. Which of the substances will still be in the liquid state at this higher temperature? A nitrogen only B xenon only C a mixture of nitrogen and oxygen D a mixture of oxygen and xenon ���

5 6 An element, R, has p protons and n neutrons in its nucleus. Which of the following gives a possible correct number of protons, neutrons and electrons in a negative ion of an isotope of R? protons neutrons electrons A p n + 1 p + 1 B p n + 1 p − 1 C p + 1 n p + 1 D p + 1 n p − 1 7 Which statement explains why potassium chloride, KCl, has a lower melting point than calcium oxide, CaO? A Potassium is more reactive than calcium. B The melting point of potassium is lower than calcium. C Potassium chloride is covalent but calcium oxide is ionic. D The forces of attraction between K+ and Cl− is weaker than that between Ca2+ and O2−. 8 Which particles are responsible for the conduction of electricity through metals? A electrons only B electrons and positive ions C negative ions only D negative ions and positive ions 9 The atomic numbers and mass numbers of elements P and Q are given below: element atomic Number mass number P 20 40 Q 9 19 What is the relative molecular mass of the compound formed between P and Q? A 29 B 38 C 59 D 78 10 68 g of hydrogen peroxide decomposes in the presence of manganese(IV) oxide to give 1.2 dm3 of oxygen gas as follows. 2H2O2 → O2 + 2H2O What is the percentage purity of the hydrogen peroxide? A 2.5% B 5.0% C 10.0% D 15.0% ���

6 11 In an experiment, 4.0 cm3 of 1.0 mol/dm3 aqueous copper(II) sulfate and 8.0 cm3 of 1.0 mol/dm3 aqueous sodium carbonate are mixed. CuSO4(aq) + Na2CO3(aq) → Na2SO4(aq) + CuCO3(s) What does the reaction vessel contain once the reaction is complete? A a colourless solution only B a green precipitate and a blue solution C a green precipitate and a colourless solution D a white precipitate and a colourless solution 12 Elements X, Y and Z are all in the same period of the Periodic Table. X forms an amphoteric oxide. Solid Y does not conduct electricity. Z forms an ionic oxide, ZO. In which order do the elements appear in the Periodic Table? A X → Y → Z B Y → X → Z C Z → X → Y D Z → Y→ X 13 20 cm3 of an aqueous 1.0 mol/dm3 solution of the hydroxide of metal X, exactly neutralises 60 cm3 of aqueous 0.5 mol/dm3 sulfuric acid. What is the formula for the sulfate of X? A X2SO4 B XSO4 C X2(SO4)3 D X(SO4)2 14 The information below concerns 3 elements X, Y and Z. X: Its oxide is decomposed by heat to the element. Y: Its carbonate is not decomposed by heat. Z: Its oxide is not decomposed by heat but its carbonate decomposes. In order of decreasing reactivity, the 3 elements should be arranged as A Y, Z, X B X, Y, Z C Y, X, Z D X, Z, Y ���

7 15 The oxides of three elements, T, U and V, are added to water. oxide of T oxide of U oxide of V water added dissolved to form a solution of pH 2 insoluble dissolved to form a solution of pH 10 The oxide of U is white in colour. What are T, U and V? T U V A calcium aluminium sulfur B calcium copper sulfur C sulfur aluminium calcium D sulfur copper calcium 16 Which of the following reagents cannot be used to differentiate sodium hydroxide solution from sodium chloride solution? A aqueous calcium nitrate solution B aqueous copper(II) nitrate solution C aqueous lithium nitrate solution D aqueous zinc nitrate solution 17 An indicator has just been produced in the laboratory. The table shows the colours of the indicator at different pH values. pH colour 0 – 3 red 3.5 – 5 green 6 – 14 purple This new indicator would be suitable for distinguishing A aqueous potassium nitrate and aqueous potassium hydroxide. B aqueous hydrogen chloride and carbon dioxide. C aqueous ammonia and aqueous potassium hydroxide. D water and aqueous potassium chloride. ���

8 18 Y is a white solid mixture that has the following properties. Y dissolves in water. When dilute hydrochloric acid is added to an aqueous solution of Y, bubbles are produced. When chlorine is bubbled through an aqueous solution of Y, the solution turns red-brown. What is present in Y? A calcium carbonate, CaCO3, and potassium bromide, KBr B copper(II) carbonate, CuCO3, and magnesium iodide, MgI2 C sodium carbonate, Na2CO3, and sodium bromide, NaBr D sodium nitrate, NaNO3, and ammonium bromide, NH4Br 19 An atmospheric pollutant can be removed by the process of reduction. Which pollutant is removed by this process? A carbon monoxide in a catalytic convertor B nitrogen dioxide in acid rain by reaction with calcium carbonate C nitrogen oxide in a catalytic convertor D sulfur dioxide from flue gases by reaction with calcium carbonate 20 An aqueous ammonia is added to a solution of a salt. A white precipitate is formed which dissolves in an excess of aqueous ammonia. Which metal ion could the salt contain? A Al3+ B Ca2+ C Cu2+ D Zn2+ 21 Iron pipes corrode rapidly when exposed to seawater. Which metal, when attached to the iron pipes, would not offer protection against corrosion? A aluminium B magnesium C copper D zinc 22 Steel is an alloy of iron with a very small percentage of carbon. Which statement is correct? A A decrease in the percentage of carbon makes the steel more brittle. ���

9 B An increase in the percentage of carbon makes the steel softer. C Carbon disrupts the metallic structure of iron. D Iron atoms are the same size as carbon atoms. 23 Which of the underlined substances acts as a reducing agent? A 2Mg + O2 → 2MgO B Cu2+ + Zn → Cu + Zn2+ C FeO + H2SO4 → FeSO4 +