Chemistry 0620/32 October/November 2025: question paper and mark scheme

Question

Fig. 1.1 shows part of the Periodic Table. I II III IV V VI VII VIII H He B C N O Ne Na Cl K Ca Fe Zn Br Ag I Fig. 1.1 Answer the following questions using only the symbols of the elements in Fig. 1.1. Each symbol may be used once, more than once or not at all. Give the symbol of the element that: (a) is used as a lubricant …… [1] (b) forms an ion which is present in every dilute acid …… [1] (c) is a metal which does not react with steam …… [1] (d) is in Period 3 and forms an ion with a charge of 1– when it reacts. …… [1] [Total: 4] * 0000800000003 * DFD 3

Question

The symbol for an atom of krypton is shown. 84 36 Kr 84Kr . (a) Complete Table 2.1 to show the number of electrons and neutrons in one atom of 36 Table 2.1 number of electrons number of neutrons [2] (b) Krypton is a gas at room temperature and pressure. A sample of krypton is placed in a sealed syringe with a freely moving plunger. Complete Table 2.2 to show the effect, if any, on the volume of krypton when: • the temperature of the krypton is decreased • the pressure of the krypton is increased. Use the words increases, decreases or no change in your answer. Table 2.2 change effect on the volume of krypton temperature is decreased pressure is increased [2] (c) When krypton is cooled, it becomes a liquid. Describe the arrangement of the particles in liquid krypton. Give your answer in terms of particle separation and motion. particle separation …… particle motion …… [2] [Total: 6] * 0000800000004 * DFD 4

Question

(a) Table 3.1 shows the masses of ions, in mg, present in a 500 cm3 sample of contaminated water. Table 3.1 mass of ion in 500 cm3 name of ion formula of ion of contaminated water / mg ammonium 2.5 chloride Cl – 4.2 hydrogencarbonate HCO3– 6.0 iodide I– 0.4 lithium Li+ 4.3 magnesium Mg2+ 0.8 nitrate NO3– 8.5 phosphate PO43 – 0.7 potassium K+ 9.3 sulfate SO42 – 0.3 Answer these questions using the information from Table 3.1. (i) Name the negative ion that has the highest concentration. …… [1] (ii) State the formula of the ammonium ion. …… [1] (iii) Describe a test to identify the presence of chloride ions, Cl –, in a sample of water. test …… observations …… [2] (iv) Calculate the mass of hydrogencarbonate ions, HCO3– , in 200 cm3 of the contaminated water. mass = …… mg [1] * 0000800000005 * DFD 5 (b) The water sample is not suitable for use in practical chemistry. Name a process that makes the water suitable for use in practical chemistry. …… [1] (c) Water extracted from a river is made suitable for drinking by filtration and then treatment with carbon followed by chlorination. (i) State why carbon is used in the treatment of water. …… [1] (ii) State why water is chlorinated. …… [1] (d) Fig. 3.1 shows the apparatus used to analyse a sample of water containing coloured substances and the results obtained. Fig. 3.1 (i) Name the separation method shown in Fig. 3.1. …… [1] (ii) Label the solvent front in Fig. 3.1. [1] [Total: 10] DFD 6 * 0000800000007 * DFD 7

Question

(a) Molecules of compound A are found in some plants. Fig. 4.1 shows the displayed formula of a molecule of compound A. H H H H H O H H H C H C C C C C C C H H C H H C H H H H H Fig. 4.1 Deduce the molecular formula of compound A to show the number of atoms of carbon, hydrogen and oxygen. …… [1] (b) On Fig. 4.1, draw a circle around one part of the molecule responsible for the decolourisation of aqueous bromine. [1] (c) A different molecule found in plants has the molecular formula C10H16O2 . Complete Table 4.1 to calculate the relative molecular mass of C10H16O2 . Table 4.1 relative type of atom number of atoms atomic mass carbon 10 12 10 × 12 = 120 hydrogen 1 oxygen 16 relative molecular mass = …… [2] * 0000800000008 * DFD 8 (d) Petroleum is a fossil fuel. Name one other fossil fuel. …… [1] (e) Fig. 4.2 shows the names of some of the fractions obtained from petroleum using a fractionating column. gasoline / petrol naphtha kerosene / paraffin diesel oil / gas oil fuel oil lubricating oil petroleum Fig. 4.2 Using only the fractions shown in Fig. 4.2, name the fraction which contains compounds that: (i) have the longest chain length …… [1] (ii) have the highest volatility …… [1] (iii) are used for home heating systems. …… [1] (f) Table 4.2 shows some properties of hydrocarbons found in fuel for jet engines. Table 4.2 molecular melting point boiling point name formula / °C / °C nonene C9H18 –81 147 decane C10H22 –30 174 undecane C11H24 –26 195 dodecane C12H26 –10 216 tridecane C13H28 –5 234 * 0000800000009 * DFD 9 (i) Identify the unsaturated hydrocarbon in Table 4.2. …… [1] (ii) Explain your answer in (f)(i). …… [1] (g) (i) In excess oxygen, decane undergoes complete combustion to produce carbon dioxide and one other product. Identify this other product. …… [1] (ii) State one adverse effect to the environment of the production of carbon dioxide. …… [1] (h) (i) Ethanol can be used to make jet fuel. Draw the displayed formula of ethanol. Show all the atoms and all the bonds. [2] (ii) Ethanol can be manufactured from ethene and one other reactant. Name the other reactant, and state the temperature and pressure used. reactant …… temperature …… °C pressure …… atm [3] [Total: 17] * 0000800000010 * DFD 10

Question

This question is about elements in different groups of the Periodic Table and their compounds. (a) Nitrogen is in Group V of the Periodic Table. Explain why nitrogen is placed in Group V. Give your answer in terms of electronic configuration. …… [1] (b) Tellurium is in Group VI of the Periodic Table. Table 5.1 shows the melting point and the boiling point of tellurium. Table 5.1 melting point / °C 450 boiling point / °C 988 Use Table 5.1 to deduce the physical state of tellurium at 650 °C. Give a reason for your answer. physical state …… reason …… [2] (c) Bromine is in Group VII of the Periodic Table. Give the colour and state of bromine at room temperature and pressure. colour …… state …… [2] (d) When a sample of sodium is added to a large container of cold water, a chemical reaction occurs. (i) Describe what is observed when sodium is added to water. …… [3] * 0000800000011 * DFD 11 (ii) Complete the word equation for the reaction of sodium with water. sodium + water …… + hydrogen …… [1] (e) Sodium carbonate reacts with sulfuric acid to form sodium sulfate, carbon dioxide and one other product. Complete the symbol equation for this reaction. Na2CO3 + …… Na2SO4 + CO2 + …… [2] (f) Solid sodium hydroxide is slowly added to distilled water containing a few drops of thymolphthalein and the mixture is stirred. (i) State the colour change observed when sodium hydroxide is added to water containing thymolphthalein. from …… to …… [2] (ii) Aqueous sodium hydroxide is an alkali. Complete the sentence about an alkali using one of the words from the list. acid base indicator salt An alkali is a soluble …… . [1] (g) Fluorine is in Group VII of the Periodic Table. Fluorine reacts with sodium to form the ionic compound sodium fluoride. Complete the dot-and-cross diagram in Fig. 5.1 for sodium fluoride to show: • the electronic configuration for each ion • the charge on each ion. Na F Fig. 5.1 [3] [Total: 17] * 0000800000012 * DFD 12

Question

This question is about metals. (a) Iron is extracted from its ore using carbon in a blast furnace. Aluminium is extracted from its ore using electrolysis. (i) Name the main ore of aluminium. …… [1] (ii) Explain why aluminium is not extracted from its ore by reduction with carbon. Give your answer in terms of the reactivity series. …… [1] (iii) An equation for the reduction of iron(III) oxide using carbon is shown. 2Fe2O3 + 3C 4Fe + 3CO2 Explain how this equation shows that iron(III) oxide is reduced. …… [1] (b) Iron is made into stainless steel. Stainless steel is an alloy that resists rusting. (i) State what is meant by the term alloy. …… [2] (ii) Name the two substances required for iron to rust. …… and …… [2] (iii) State the chemical name for rust. * 0000800000013 * DFD 13 (c) Table 6.1 shows the observations when four different metals are added separately to dilute hydrochloric acid. Table 6.1 metal observations bubbles of gas given off quickly and the temperature Mn of the mixture increases slowly a few bubbles of gas given off very slowly and Fe the temperature of the mixture increases very slowly many bubbles of gas given off very quickly and the Sr temperature of the mixture increases rapidly no bubbles of gas given off and Nb no temperature increase of the mixture (i) Put the four metals in order of their reactivity. Put the least reactive metal first. least reactive most reactive [2] (ii) Complete the word equation for the reaction of strontium with hydrochloric acid. hydrochloric …… strontium + + …… acid [2] [Total: 13] * 0000800000014 * DFD 14

Question

Fig. 7.1 shows the apparatus used to pass electricity through molten magnesium chloride using platinum electrodes. power supply + – crucible Fig. 7.1 (a) Name the process shown in Fig. 7.1. …… [1] (b) Label the electrolyte in Fig. 7.1. [1] (c) Name the product formed at the anode. …… [1] (d) The electrodes are made of platinum. (i) State one property of platinum that makes it suitable for use as an electrode. …… [1] (ii) Suggest a non-metal that could be used as the electrodes. …… [1] (e) State whether the process shown in Fig. 7.1 produces a physical or chemical change. Explain your answer. type of change …… explanation …… [1] * 0000800000015 * DFD 15 (f) Magnesium chloride, MgCl 2, exists in different forms. Draw one line from each form of magnesium chloride to its description. form of magnesium chloride description solid MgCl 2 chemically aqueous MgCl 2 combined with water anhydrous MgCl 2 MgCl 2 dissolved in water solid MgCl 2 containing hydrated MgCl 2 no water [2] [Total: 8] * 0000800000016 * DFD 16

Question

Excess dilute hydrochloric acid is added to aqueous sodium sulfide to form aqueous sodium chloride and gaseous hydrogen sulfide, H2S. 2HCl (aq) + Na2S(aq) 2NaCl (aq) + H2S(g) Fig. 8.1 shows the total volume of hydrogen sulfide gas, H2S, produced as the reaction proceeds. 150 125 100 total volume of H2S / cm3 75 50 25 0 0 20 40 60 80 100 120 140 time / s Fig. 8.1 (a) Use Fig. 8.1 to determine the total volume of H2S produced when the reaction is complete. total volume of H2S = …… cm3 [1] * 0000800000017 * DFD 17 (b) The reaction is repeated using hydrochloric acid of a higher concentration. All other conditions stay the same. State the effect, if any, on: (i) the time taken for the reaction to finish …… [1] (ii) the total volume of H2S produced when the reaction is complete. …… [1] (c) Fig. 8.2 shows the reaction pathway diagram for the reaction of dilute hydrochloric acid with aqueous sodium sulfide. 2HCl + Na2S energy 2NaCl + H2S progress of reaction Fig. 8.2 Deduce the type of energy change shown in the diagram in Fig. 8.2. Explain your answer. …… [2] [Total: 5] DFD 18 * 0000800000019 * DFD 19 The Periodic Table of Elements Group I II III IV V VI VII VIII 1 2 H He hydrogen helium Key 1 4 3 4 atomic number 5 6 7 8 9 10 Li Be atomic symbol B C N O F Ne lithium beryllium name boron carbon nitrogen oxygen fluorine neon 7 9 relative atomic mass 11 12 14 16 19 20 11 12 13 14 15 16 17 18 Na Mg Al Si P S Cl Ar sodium magnesium aluminium silicon phosphorus sulfur chlorine argon 23 24 27 28 31 32 35.5 40 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 DFD K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr potassium calcium scandium titanium vanadium chromium manganese iron cobalt nickel copper zinc gallium germanium arsenic selenium bromine krypton 39 40 45 48 51 52 55 56 59 59 64 65 70 73 75 79 80 84 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe rubidium strontium yttrium zirconium niobium molybdenum technetium ruthenium rhodium palladium silver cadmium indium tin antimony tellurium iodine xenon 20 85 88 89 91 93 96 – 101 103 106 108 112 115 119 122 128 127 131 55 56 57–71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 lanthanoids Cs Ba Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn caesium barium hafnium tantalum tungsten rhenium osmium iridium platinum gold mercury thallium lead bismuth polonium astatine radon 133 137 178 181 184 186 190 192 195 197 201 204 207 209 – – – 87 88 89–103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 actinoids Fr Ra Rf Db Sg Bh Hs Mt Ds Rg Cn Nh Fl Mc Lv Ts Og francium radium rutherfordium dubnium seaborgium bohrium hassium meitnerium darmstadtium roentgenium copernicium nihonium flerovium moscovium livermorium tennessine oganesson – – – – – – – – – – – – – – – – – 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 lanthanoids La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu lanthanum cerium praseodymium neodymium promethium samarium europium gadolinium terbium dysprosium holmium erbium thulium ytterbium lutetium 139 140 141 144 – 150 152 157 159 163 165 167 169 173 175 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 actinoids Ac Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr actinium thorium protactinium uranium neptunium plutonium americium curium berkelium californium einsteinium fermium mendelevium nobelium lawrencium – 232 231 238 – – – – – – – – – – – The volume of one mole of any gas is 24 dm3 at room temperature and pressure (r.t.p.).