2 1 (a) The electronic structures of five atoms, A, B, C, D and E, are shown. A B C D E nswer the following questions about these electronic structures. A Each electronic structure may be used once, more than once or not at all. State which electronic structure, A, B, C, D or E, represents: (i) an atom in Group II of the Periodic Table . ...................................................................................................................................... [1] (ii) an atom with a proton number of 13 . ...................................................................................................................................... [1] (iii) an atom that forms a stable ion with a single negative charge . ...................................................................................................................................... [1] (iv) an atom of a non-metal that forms a giant covalent structure . ...................................................................................................................................... [1] (v) an atom of a metal used in food containers. . ...................................................................................................................................... [1] (b) C omplete the table to show the number of electrons, neutrons and protons in the vanadium atom and calcium ion shown. number of number of number of electrons neutrons protons 23V 51 23 20Ca 48 2+ 28 [3] [Total: 8] © UCLES 2021 0620/31/M/J/21
3 2 The table shows the masses of some of the ions in 1000 cm3 of fruit juice. mass of ion in 1000 cm3 name of ion formula of ion of fruit juice / mg NH4+ 43 calcium Ca2+ 79 chloride Cl – 135 lithium Li+ 1 magnesium Mg2+ 80 nitrate NO3– 35 phosphate PO43– 120 potassium K+ 575 sodium Na+ 120 SO42– 105 (a) Answer these questions using only the information in the table. (i) State which negative ion has the highest mass in 1000 cm3 of fruit juice. . ...................................................................................................................................... [1] (ii) Give the formulae of the ions in ammonium sulfate. ................................................................ and . .............................................................. [1] (iii) Calculate the mass of sodium ions in 200 cm3 of fruit juice. mass = .............................. mg [1] (b) Describe a test for lithium ions. test . ............................................................................................................................................ observations ............................................................................................................................... [2] (c) Ions of the element potassium, K, are present in most fertilisers. State the names of two other elements that are in most fertilisers. 1 ................................................................................................................................................. 2 ................................................................................................................................................. [2] © UCLES 2021 0620/31/M/J/21 [Turn over
4 (d) Orange juice is acidic. Draw a circle around the pH of orange juice. pH 4 pH 7 pH 10 pH 13[1] (e) Some soils are acidic. Give the names of two compounds that are used to make soils less acidic. 1 ................................................................................................................................................. 2 ................................................................................................................................................. [2] (f) Hydrogen chloride is an acidic gas produced when concentrated hydrochloric acid evaporates. (i) Describe the arrangement and separation of the molecules in hydrogen chloride gas. arrangement ........................................................................................................................ . ............................................................................................................................................ separation . .......................................................................................................................... . ............................................................................................................................................ [2] (ii) A long glass tube is set up as shown. long glass tube cotton wool soaked in damp blue litmus paper concentrated hydrochloric acid t first, the blue litmus paper does not turn red. A After a short time, the litmus paper turns red. Explain these observations using the kinetic particle model. . ............................................................................................................................................ . ............................................................................................................................................ . ............................................................................................................................................ . ............................................................................................................................................ . ...................................................................................................................................... [3] [Total: 15] © UCLES 2021 0620/31/M/J/21
5 3 The table shows some properties of four Group I elements. melting point boiling point atomic radius element / °C / °C / nm sodium 98 883 0.191 potassium 63 760 rubidium 39 0.250 caesium 29 671 0.272 C (a) (i) omplete the table by predicting: ● the boiling point of rubidium ● the atomic radius of potassium. [2] (ii) Describe the trend in the melting point of the Group I elements down the group. . ...................................................................................................................................... [1] (iii) educe the physical state of potassium at 60 °C. D Explain your answer. . ............................................................................................................................................ . ............................................................................................................................................ . ...................................................................................................................................... [2] (b) Caesium is a radioactive element with a proton number of 55. (i) Define proton number. . ...................................................................................................................................... [1] (ii) State one industrial use of radioactive isotopes. . ...................................................................................................................................... [1] (c) Sodium hydride, NaH, reacts with iron(III) oxide. (i) Balance the equation for this reaction. Fe2O3 + 3NaH → .....Fe + .....NaOH [2] (ii) Explain how this equation shows that iron(III) oxide is reduced. . ...................................................................................................................................... [1] [Total: 10] © UCLES 2021 0620/31/M/J/21 [Turn over
6 4 The structure of malic acid is shown. H O O C H C O H H C H C H O O (a) (i) On the structure draw a circle around the alcohol functional group. [1] (ii) educe the formula of malic acid to show the number of carbon, hydrogen and oxygen D atoms. . ...................................................................................................................................... [1] (b) When malic acid is heated it forms compound F. The structure of compound F is shown. H O O C H C C H C H O O Explain why compound F is described as unsaturated. .............................................................................................................................................. [1] (c) Compound F can form polymers. (i) State the meaning of the term polymer. . ............................................................................................................................................ . ...................................................................................................................................... [2] (ii) State the name of the polymer formed when ethene is polymerised. . ...................................................................................................................................... [1] © UCLES 2021 0620/31/M/J/21
7 (d) Ethanoic acid is a carboxylic acid. Describe the observations made when dilute ethanoic acid reacts with: magnesium ................................................................................................................................. litmus solution. . .......................................................................................................................... [2] (e) T he graph shows how the pH changes when dilute ethanoic acid is added slowly to aqueous sodium hydroxide. 14 12 10 pH 8 6 4 2 0 10 20 30 40 volume of dilute ethanoic acid added / cm3 (i) Deduce the pH of the aqueous sodium hydroxide before the addition of dilute ethanoic acid. pH = .............................. [1] (ii) Deduce the volume of dilute ethanoic acid added when the pH is neutral. .............................. cm3 [1] [Total: 10] © UCLES 2021 0620/31/M/J/21 [Turn over
8 5 (a) Calcium oxide is made by the thermal decomposition of calcium carbonate. (i) State the meaning of the term thermal decomposition. . ............................................................................................................................................ . ...................................................................................................................................... [2] (ii) Describe a test for calcium ions. test . ..................................................................................................................................... observations ........................................................................................................................ [2] (b) Carbon dioxide is produced when dilute hydrochloric acid reacts with calcium carbonate. CaCO3 + 2HCl → CaCl 2 + CO2 + H2O (i) Complete the diagram to show how to measure the volume of carbon dioxide produced during this reaction. dilute hydrochloric acid calcium carbonate [2] © UCLES 2021 0620/31/M/J/21
9 (ii) escribe the effect of each of the following on the rate of reaction of dilute hydrochloric acid D with calcium carbonate. ● The concentration of hydrochloric acid is decreased. All other conditions stay the same. . ............................................................................................................................................ ● The temperature is increased. All other conditions stay the same. . ............................................................................................................................................ [2] (c) Carbon dioxide is also formed when the hydrocarbon C3H8 is completely combusted. (i) State the meaning of the term hydrocarbon. . ............................................................................................................................................ . ...................................................................................................................................... [2] (ii) The hydrocarbon C3H8 is called propane. Name the homologous series that propane belongs to. . ...................................................................................................................................... [1] (iii) Name two substances formed by the incomplete combustion of propane. ................................................................ and . .............................................................. [2] [Total: 13] © UCLES 2021 0620/31/M/J/21 [Turn over
10 6 This question is about water. (a) The water in rivers often contains pollutants such as acids. Describe how universal indicator paper can be used to determine the pH value of the water. .................................................................................................................................................... .................................................................................................................................................... .............................................................................................................................................. [2] (b) The diagram shows some of the stages in water treatment. impure aeration mixing purified filter water tank tank water air chlorine (i) Air is blown through the aeration tank. Name the two gases that make up most of the air. ................................................................ and . .............................................................. [2] (ii) After aeration, the water still contains large insoluble particles. The filter is made up of fine sand and stones. Explain how the filter helps purify the water. . ............................................................................................................................................ . ............................................................................................................................................ . ...................................................................................................................................... [2] (iii) Explain why chlorine is used in water treatment. . ...................................................................................................................................... [1] (c) Anhydrous cobalt(II) chloride is used to test for water. State the colour change in this test. from ................................................................ to ................................................................. [2] [Total: 9] © UCLES 2021 0620/31/M/J/21
11 7 (a) Molten lead(II) bromide is electrolysed using carbon electrodes. (i) State the products of this electrolysis at: the negative electrode ......................................................................................................... the positive electrode. . ........................................................................................................ [2] (ii) State the name of another substance which can be used as an inert electrode. . ...................................................................................................................................... [1] (b) W hen aqueous magnesium chloride is electrolysed using carbon electrodes, hydrogen gas is produced at the negative electrode. omplete the dot-and-cross diagram to show the electron arrangement in one molecule of C hydrogen. [1] [Total: 4] © UCLES 2021 0620/31/M/J/21 [Turn over