Whitley Prelim P1

Name: ( ) Class: WHITLEY SECONDARY SCHOOL A Caring and Learning Community of Leaders Perseverance * Respect * Integrity * Discipline * Empathy PRELIMINARY EXAMINATION 2024 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 16. The use of an approved scientific calculator is expected, where appropriate. This paper consists of 16 printed pages. SUBJECT : Chemistry (6092/01) LEVEL : Secondary 4 Express DATE : 23 August 2024 DURATION : 1 hour SETTER : Mrs Ambikai VETTERS : Ms Charlene Lye and Mr Ng Mun Leong

2 2 1. Stearic acid has a melting point of 69oC. A heated sample of pure stearic acid is cooled and the temperature is recorded every minute for 30 minutes. A graph of the results is shown. Which process occurs between 8 and 12 minutes? A boiling B condensing C freezing D melting 2. Two samples of a colourless solution are tested separately with aqueous sodium hydroxide, NaOH(aq), and aqueous ammonia, NH3(aq), and the results are recorded.  A white precipitate is formed with two drops of NaOH(aq). This precipitate dissolves in an excess of NaOH(aq).  A white precipitate is formed with two drops of NH3(aq). This precipitate dissolves in an excess of NH3(aq). What can be deduced from these results? A The anion present is Cl-. B The anion present is not Cl-. C The cation present is Al3+. D The cation present is Zn2+.

3 3 3. A student uses paper chromatography to find an Rf value for Fe3+(aq). The result is shown. To make the spot containing Fe3+(aq) more visible, the paper is sprayed with aqueous sodium hydroxide so that a precipitate of iron(III) hydroxide forms. Under the conditions of the experiment, the Rf value of Fe3+(aq) is given by …..1….. The colour of the precipitate is …..2….. . Which row correctly completes gaps 1 and 2? 1 2 A 𝑥𝑦 green B 𝑥𝑦 red-brown C 𝑦𝑥 green D 𝑦𝑥 red-brown

4 4 4. The diagram shows a diffusion experiment. Which gas, when present in the beaker over the porous pot, will cause the water level at Y to rise? A carbon dioxide B chlorine C methane D nitrogen dioxide 5. Two particles have the symbols Feଶ଺ହସ2+ and Coଶ଻ହଽ3+. Which statement about these particles is correct? A They contain the same number of electrons. B They contain the same number of neutrons. C They contain the same number of protons. D They do not contain the same number of protons, neutrons or electrons. 6. Magnesium exists in three stable isotopes, Mg-24, Mg-25, Mg-26. Which statements are correct about the properties of the isotopes? 1 The isotopes have the same number of electrons in their outermost shells. 2 The isotopes have the same physical properties. 3 The isotopes react with hydrochloric acid in the same manner. A 1 and 2 only B 1 and 3 only C 2 and 3 only D 1, 2 and 3

5 5 7. What happens to an atom of a Group 2 element when it forms a compound with oxygen? A It bonds with two atoms of oxygen. B It takes two electrons from an atom of oxygen. C It shares two electrons with an atom of oxygen. D It transfers two electrons to an atom of oxygen. 8. Which statements about the substances, at room temperature and pressure, is correct? A W and X conduct electricity. B W and Y are elements. C X and Z dissolve in water. D Y and Z have low melting points. 9. Ethane, C2H6, and ammonia, NH3, are covalent compounds. The dot and cross diagrams of these compounds are shown below. Which statements are correct? 1 A molecule of ethane contains twice as many hydrogen atoms as a molecule of ammonia. 2 An unreacted nitrogen atom has five outer electrons. 3 In a molecule of ethane, the bond between the carbon atoms is formed by sharing two electrons, one from each carbon atom. A 1, 2 and 3 B 1 and 2 only C 1 and 3 only D 2 and 3 only 10. A series of experiments were carried out to investigate the properties of a newly discovered substance. Which observation shows that the substance cannot be an element? A It melts at a fixed temperature. B It forms cation with two oxidation states. C It decomposes to give a colourless gas when heated in the air. D Electrolysis of the molten substances gave one product.

6 6 11. The relative molecular mass, Mr, of liquid Z is 60. Z contains 40.0% carbon, 6.70% hydrogen and 53.3% oxygen. Which row shows the correct empirical and molecular formulae of Z? empirical formula molecular formula A CH2O CH 2O B CH2O C2H4O2 C C2H4O2 C2H4O2 D CH3O C 2H6O2 12. The equation for the reaction between ethyne, C2H2, and oxygen is shown. 2C2H2(g) + xO2(g) → yCO2(g) + zH2O(g) When the equation is balanced, what is x? A 2 B 3 C 4 D 5 13. Aqueous silver nitrate, AgNO3, reacts with aqueous potassium chromate (VI), K2CrO4, to give a yellow precipitate. What is the ionic equation for this reaction? A 2AgNO3 (aq) + K2CrO4 (aq)  Ag2CrO4 (s) + 2KNO3(aq) B 2Ag+ (aq) + 2NO3– (aq) + 2K+ (aq) + CrO42–(aq)  Ag2CrO4 (s) + 2NO3– (aq) + 2K+ (aq) C 2Ag+ (aq) + CrO42–(aq)  Ag2CrO4(s) D Ag+ (aq) + CrO4 – (aq)  AgCrO4(s) 14. When gases react, the volume of gaseous reactants may be different from the volume of gaseous products. For which reaction is the percentage change in the volume of gas largest? (Assume each reaction goes to completion.) A 2SO2(g) + O2(g)  2SO3(g) B CH4(g) + 2O2(g)  CO2(g) + 2H2O(g) C N2(g) + 3H2(g)  2NH3(g) D 2C2H6(g) + 7O2(g)  6H2O(g) + 4CO2(g) 15. An aqueous solution is made by dissolving 3.4 g of sodium hydroxide, NaOH, to make 500 cm3 of solution. What is the concentration, in mol / dm3, of this sodium hydroxide solution? A 0.0068 B 0.085 C 0.17 D 6.8

7 7 16. The table below shows the results of different experiments conducted in two acids, X and Y, of equal concentration. X Y conductivity of solution 400 mS 7.0 mS temperature change when excess acid reacted with 100cm3 of 1.0 mol/dm3 sodium hydroxide 6.9 oC 6.7 oC reaction with magnesium Hydrogen gas produced rapidly with rapid effervescence Hydrogen gas produced slowly with gradual effervescence (mS is the unit for conductivity) Which of the following deductions can be made about acids X and Y? A X is a weak acid but Y is a strong acid. B X is a strong acid but Y is a weak acid. C Both X and Y are strong acids, but 1 mole of X gives 1 mole of hydrogen ions while 1 mole of Y gives 2 moles of hydrogen ions. D Both X and Y are strong acids, but 1 mole of X gives 2 moles of hydrogen ions while 1 mole of Y gives 1 mole of hydrogen ions. 17. 1.0 g of the following oxides are added separately to water. Which of the following shows the correct pH of the resulting solution? oxide pH of the resulting solution A sulfur dioxide 13 B sodium oxide 8 C carbon monoxide 4 D nitrogen dioxide 2 18. The table shows the colour change for three pH indicators used in the laboratory. indicator colour change low pH  high pH pH at which colour change takes place phenolphthalein colourless to pink 9.0 bromothymol blue yellow  blue 6.5 methyl orange red  ye