Copy of CHS 2024 S4 OP Prelim Paper 2 Section B

[Turn Over Name: Index Number: Class: CATHOLIC HIGH SCHOOL Preliminary Examination Secondary 4 ‘O’ Level Programme CHEMISTRY 6092/02 Paper 2 20 August 2024 1 hour 45 minutes Candidates answer on the Question Paper. No Additional Materials are required. READ THESE INSTRUCTIONS FIRST Write your name, index number and class on all the work you hand in. Write in dark blue or black pen. You may use an HB pencil for any diagrams or graphs. Do not use staples, paper clips, glue or correction fluid. Section B Answer one question. Write your answers in the spaces provided. The number of marks is given in brackets [ ] at the end of each question or part question. A copy of the Periodic Table is printed on page 6. The use of an approved scientific calculator is expected, where appropriate. For examiner’s use only: Section B / 10 This document consists of 6 printed pages. B

2 Section B Answer one question from this section. 10 Malonic acid is a white crystalline solid which is soluble in water. Fig. 10.1 shows the structural formula of malonic acid. CH2(COOH)2 or HOOC–CH2–COOH Fig. 10.1 Malonic acid ionises according to the equation below. CH2(COOH)2 ⇌ 2H+ + CH2(COO)22− (a) State one similarity between the acidic behaviour of malonic acid and sulfuric acid. ……………………………………………………………………………………………………... …………………………………………………………………………………………….….… [1] (b) Experiments are carried out using equal volumes of malonic acid and sulfuric acid of the same concentration to investigate their properties. Compare and explain the properties of malonic acid and sulfuric acid. Your answer should include a discussion of the similarities and differences in their • pH • reaction with excess solid sodium carbonate. …………………………………………………………………………….……………………….. ………………………………………………………………………….………………………….. ………………………………………………………………………….………………………….. …………………………………………………………………………………….……………….. …………………………………………………………………………………….……………….. …………………………………………………………………………………….……………….. …………………………………………………………………………………….……………….. …………………………………………………………………………………….……………….. …………………………………………………………………………………….……………. [5]

3 [Turn Over (c) Compound A, C3H8O2, reacts with acidified potassium manganate( VII) to form malonic acid. (i) Name the type of reaction compound A undergoes to form malonic acid. ………………………………………………………………………………………..... [1] (ii) Draw the displayed formula of compound A. [1] (iii) Name the homologous series that contains the functional group in compound A. ………………………………………………………………………………………..... [1] (iv) Using a different reagent, compound A forms compound B. The structure of compound B is shown in Fig. 10.2. H–C–CH2–C–H Fig. 10.2 Are malonic acid and compound B isomers? Explain your reasoning. ……………………………………………………………………………………………... …………………………………………………………………………………………. [1] [Total: 10] O O

4 11 (a) Cyclohexane is a saturated hydrocarbon while hexene is a n unsaturated hydrocarbon. Fig. 11.1 shows the structures of cyclohexane and hexene. CH3CH2CH2CH2CH=CH2 cyclohexane hexene Fig. 11.1 (i) Are cyclohexane and hexene isomers? Explain your reasoning. ……………………………………………………………………………………………… ……………………………………………………………………………………...…… [1] (ii) Compare the properties of cyclohexane and hexene. Your answer should include a discussion of the similarities and differences in their • combustion reaction • reaction with aqueous bromine. Include equations and observations , where necessary, for any reactions you discuss. ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… …...……………………………………………………………………………………… [5]

5 [Turn Over (b) Vegetable oils react with methanol to produce a biofuel. Fig. 11.2 shows the structures of some of the molecules involved in the reaction. Fig. 11.2 (i) Name the homologous series that contains the functional group in vegetable oil. ……………………………………………………………………………………...…… [1] (ii) One molecule of vegetable oil reacts to form three molecules of biofuel. The biofuel and vegetable oil contain the same functional group. Suggest the displayed formula of one molecule of biofuel. Use to represent the hydrocarbon chain. [1] (iii) Explain why bio fuel is considered a renewable and more environmentally sustainable energy source compared to diesel obtained from crude oil. ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………...…… [2] [Total: 10] - End of Paper - 3 biofuel molecules Key: hydrocarbon chain vegetable oil methanol

6 The Periodic Table of Elements Group 1 2 13 14 15 16 17 18 Key 1 H hydrogen 1 2 He helium 4 3 Li lithium 7 4 Be beryllium 9 proton (atomic) number atomic symbol name relative atomic mass 5 B boron 11 6 C carbon 12 7 N nitrogen 14 8 O oxygen 16 9 F fluorine 19 10 Ne neon 20 11 Na sodium 23 12 Mg magnesium 24 3 4 5 6 7 8 9 10 11 12 13 Al aluminium 27 14 Si silicon 28 15 P phosphorus 31 16 S sulfur 32 17 Cl chlorine 35.5 18 Ar argon 40 19 K potassium 39 20 Ca calcium 40 21 Sc scandium 45 22 Ti titanium 48 23 V vanadium 51 24 Cr chromium 52 25 Mn manganese 55 26 Fe iron 56 27 Co cobalt 59 28 Ni nickel 59 29 Cu copper 64 30 Zn zinc 65 31 Ga gallium 70 32 Ge germanium 73 33 As arsenic 75 34 Se selenium 79 35 Br bromine 80 36 Kr krypton 84 37 Rb rubidium 85 38 Sr strontium 88 39 Y yttrium 89 40 Zr zirconium 91 41 Nb niobium 93 42 Mo molybdenum 96 43 Tc technetium – 44 Ru ruthenium 101 45 Rh rhodium 103 46 Pd palladium 106 47 Ag silver 108 48 Cd cadmium 112 49 In indium 115 50 Sn tin 119 51 Sb antimony 122 52 Te tellurium 128 53 I iodine 127 54 Xe xenon 131 55 Cs caesium 133 56 Ba barium 137 57–71 lanthanoids 72 Hf hafnium 178 73 Ta tantalum 181 74 W tungsten 184 75 Re rhenium 186 76 Os osmium 190 77 Ir iridium 192 78 Pt platinum 195 79 Au gold 197 80 Hg mercury 201 81 Tl thallium 204 82 Pb lead 207 83 Bi bismuth 209 84 Po polonium – 85 At astatine – 86 Rn radon – 87 Fr francium – 88 Ra radium – 89–103 actinoids 104 Rf rutherfordium – 105 Db dubnium – 106 Sg seaborgium – 107 Bh bohrium – 108 Hs hassium – 109 Mt meitnerium – 110 Ds darmstadtium – 111 Rg roentgenium – 112 Cn copernicium – 113 Nh nihonium – 114 Fl flerovium – 115 Mc moscovium – 116 Lv livermorium – 117 Ts tennessine – 118 Og oganesson – lanthanoids 57 La lanthanum 139 58 Ce cerium 140 59 Pr praseodymium 141 60 Nd neodymium 144 61 Pm promethium – 62 Sm samarium 150 63 Eu europium 152 64 Gd gadolinium 157 65 Tb terbium 159 66 Dy dysprosium 163 67 Ho holmium 165 68 Er erbium 167 69 Tm thulium 169 70 Yb ytterbium 173 71 Lu lutetium 175 actinoids 89 Ac actinium – 90 Th thorium 232 91 Pa protactinium 231 92 U uranium 238 93 Np neptunium – 94 Pu plutonium – 95 Am americium – 96 Cm curium – 97 Bk berkelium – 9