2022 SKSS Chem Prelims P1

[Turn over Name and Index Number: ( ) Class: SENG KANG SECONDARY SCHOOL PRELIMINARY EXAMINATION CHEMISTRY 6092/01 Secondary 4 Express 30 August 2022 Paper 1 Multiple Choice 1 hour Additional Materials: Multiple Choice Answer Sheet READ THESE INSTRUCTIONS FIRST Write your index number and name on all the work you hand in. You may use a soft pencil for any diagrams, graphs or rough working. Do not use staples, paper clips, highlighters, glue or correction fluid. There are forty questions in 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 re cord your choice in soft pencil on the Multiple Choice 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 question paper. The use of an approved scientific calculator is expected, where appropriate. A copy of the Periodic Table is printed on page 18. Parent’s / Guardian’s Signature: ………………….…………... This document consists of 17 printed pages and 1 blank page. Do not turn over the page until you are told to do so. ���

2 [Turn over 1 The formula of magnesium oxide can be investigated from heating magnesium with oxygen to form magnesium oxide. Which apparatus are used for this investigation? A 1 and 2 only C 2 and 3 only B 1 and 3 only D 1, 2 and 3 2 A student set up the apparatus as shown. What is the gas that will be collected from the set-up and which drying agent that should be used? name of gas drying agent A ammonia concentrated sulfuric acid B ammonia calcium oxide C hydrogen chloride calcium oxide D hydrogen chloride concentrated sulfuric acid ���

3 [Turn over 3 Which statement about methods of purification and analysis is correct? A A liquid that boils over a range of temperatures may still be 100% pure. B An insoluble substance may be separated from water by crystallisation. C Chromatography may only be used to separate coloured substances. D Liquid air can be fractionally distilled, giving oxygen as one of the products. 4 Mary performed paper chromatography on a dye and obtained only one spot with an Rf value of 0.68. Which statement is true about her chromatogram? A Changing the solvent will not affect the Rf value. B Using a more concentrated dye solution will increase the Rf value. C The dye is likely to be a pure substance. D The spot is closer to the starting line than it is to the solvent front. 5 The apparatus is set up, using different gases in two inverted beakers. Which pair of gases would cause an upward movement of the water level at U? gas 1 gas 2 A hydrogen carbon dioxide B carbon dioxide hydrogen C nitrogen hydrogen D carbon dioxide nitrogen ���

4 [Turn over 6 In which of the following substances are the particles closest to each other? A dry ice C hydrogen gas B lithium fluoride solution D molten aluminium 7 The graphs (not drawn to scale) show the heating curves of oxygen and nitrogen over a period of time. Which statement about a mixture of oxygen and nitrogen is correct? A At –185 C, both oxygen and nitrogen molecules move rapidly in all directions. B At –190 C, both oxygen and nitrogen exist as a liquid. C At –200 C, both oxygen and nitrogen exist in the same state. D At –215 C, both nitrogen and oxygen molecules are vibrating about fixed positions. 8 An element with proton number 12 has a relative atomic mass of 24.4 and it is known that this element consists of two isotopes with 12 and 14 neutrons respectively. What is the ratio of the percentage abundance of the lighter isotope to the heavier isotope? A 1 : 2 C 2 : 1 B 1 : 4 D 4 : 1 ���

5 [Turn over 9 The diagram shows a structure of an ion. What is the correct position in the Periodic Table of the element from which this ion was formed? period group A 2 III B 2 0 C 3 III D 3 0 10 The proton numbers of elements X, Y and Z are 6, 8 and 12 respectively. Which row shows the correct formula of the compounds formed between the elements? formula of compound formed A Z2Y XY ZX2 B ZY XY2 ZX2 C ZY XY2 Z2X D Z2Y XY Z2X 11 Capsaicin, which is found in chilli and pepper, causes the spicy burning sensation in the mouth. It has the molecular formula C18H27NO3 and has a melting point of 65 ᵒC. Which of the following statements best explains why drinking water is ineffective in removing the burning sensation caused by capsaicin? A Capsaicin has a giant molecular structure and is soluble in water. B Capsaicin has a giant molecular structure and is not very soluble in water. C Capsaicin has a simple molecular structure and is soluble in water. D Capsaicin has a simple molecular structure and is not very soluble in water. ���

6 [Turn over 12 In the lattice structure of ionic compounds, the coordination number of each ion is the number of neighbouring ions of opposite charge. The table shows the ions present and the coordination number of the ions in some ionic compounds. Taking sodium chlori de for instance, each sodium ion is surrounded by 6 chloride ions, while each chloride ion is surrounded by 6 sodium ions. Hence, the coordination number for both the sodium ions and chloride ions is 6. ionic compound ion present coordination number of formula cation anion cation anion sodium chloride Na+ Cl- 6 6 NaCl titanium (IV) oxide Ti4+ O2- 6 3 TiO2 unknown compound Q R 4 8 ? What is the formula of the unknown compound? A QR2 C QR4 B Q2R D Q4R 13 A sample of a white crystalline substance is heated in the absence of oxygen. It melts sharply at 120 oC. On further heating, it gives off smoky fumes and a black solid remains. What can we conclude about the white crystalline substance? A an element which decomposed to simpler substance. B a mixture of substances which combined chemically. C a compound which decomposed to form simpler substance. D a compound which combusted to form two products. 14 Nitrogen monoxide gas from motor vehicle exhausts can be removed by injecting a stream of ammonia gas into the exhaust vapour. The reaction is shown below. 6NO(g) + 4NH3(g)  5N2(g) + 6H2O (g) What volume of ammonia gas is neede d to completely react with 3600 cm3 of nitrogen monoxide? A 600 cm3 C 2400 cm3 B 1200 cm3 D 5400 cm3 ���

7 [Turn over 15 In an experiment, 10 cm 3 of a gaseous hydrocarbon, X, required 75 cm 3 of oxygen for complete combustion to give 60 cm 3 of carbon dioxide. All gas volumes were measured at room temperature and pressure. What is the formula of X? A C6H6 C C6H10 B C6H8 D C12H15 16 Which of the following contains 1 mole of ions when in aqueous state? A 0.25 mol of Na3PO4 C 0.50 mol Cs2O B 0.50 mol of CO D 1.00 mol CaO 17 When an acid is titrated with a strong base, an equivalence point is reached when the amount of base added is equal to the amount of H+ dissociated. The curve for the titration of 50.0 cm 3 of 0.10 mol/dm 3 phosphoric acid, H 3PO4, against 0.10 mol/dm3 NaOH is shown. The table shows the pH range of colour changes of some acid-base indicators. indicator pH of colour changes thymol blue 1.2 - 2.8 and 8.0-9.6 naphthyl red 3.7-5.0 neutral red 6.8-8.0 Which indicators should be used to show the first and second equivalence points? A thymol blue for both C naphthyl red and then thymol blue