IGCSE Chemistry 2020 0620/21 Oct/Nov

IGCSE 2020 0620/21 Oct/Nov (pdf)

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1. Which gas has the slowest rate of diffusion?
2. A mixture of colourless amino acids is separated using chromatography.
   The solvent used is propanol.
   The chromatogram is sprayed with a locating agent.
   Which row describes the purpose of the propanol and the locating agent?
3. Which piece of apparatus can only measure a single fixed volume?
4. In the chromatography experiment shown, which label represents the solvent front?
5. The atomic structure of four particles are shown.
6. The arrangements of the electrons in two ions formed from elements X and Y are shown.
7. Which diagram shows the outer shell electron arrangement in a molecule of methanol, CH3OH?
8. Which statement about silicon dioxide, SiO2, is correct?
9. Rubidium is in Group I of the Periodic Table and bromine is in Group VII.
   Rubidium reacts with bromine to form an ionic compound.
   Which row shows the electron change taking place for rubidium and the correct formula of the rubidium ion?
10. Which statement explains why graphite is used as a lubricant?
    A All bonds between the atoms are weak.
    B It conducts electricity.
    C It has a low melting point.
    D Layers in the structure can slide over each other.

11. Sodium carbonate reacts with sulfuric acid to form carbon dioxide, water and a sodium salt.
    An incomplete equation for the reaction is shown.
12. The relative atomic mass of chlorine is 35.5.
    When calculating relative atomic mass, which particle is the mass of a chlorine atom compared to?
13. What is the empirical formula of an oxide of iron, formed by reacting 2.24 g of iron with 0.96 g of oxygen?
14. Which reaction takes place at the cathode during the electrolysis of molten nickel(II) chloride?
15. Sodium nitrate is added to water in a beaker and stirred until it dissolves.
    At the end of the experiment, the beaker feels cold.
    Which row describes the reaction?
16. Which substance does not require oxygen in order to produce energy?
17. Ethene reacts with hydrogen to form ethane.
18. A sign displayed in a flour mill is shown.
19. A student investigates the effect of concentration on the rate of reaction between calcium carbonate and hydrochloric acid. He follows the method shown.
20. The reaction between sulfur dioxide and oxygen is shown.
21. The reaction between chlorine and bromide ions is a redox reaction.
22. What is a characteristic of acids?
    A Acids turn methyl orange indicator yellow.
    B Acids have a high pH value.
    C Acids react with ammonium salts to give ammonia gas.
    D Acids react with carbonates to produce salts.
23. Zinc oxide is an amphoteric oxide.
    Which row describes the reactions of zinc oxide?
24. A student carries out an experiment to prepare pure magnesium sulfate crystals.
    The diagram shows the first stage of the preparation.
25. Elements P and Q have the same number of electron shells.
    Q has more electrons in its outer shell than P.
    Which statements are correct?
26. The positions of four elements in the Periodic Table are shown.
    Which element is a gas that displaces iodine from sodium iodide?
27. A flammable gas needs to be removed from a tank at an industrial plant.
    For safety reasons, an inert gas is used.
    Which gas is suitable?
28. A strip of aluminium is placed into a test-tube containing aqueous lead(II) nitrate and left for several minutes.
    Aluminium is higher than lead in the reactivity series.
29. Which statements about the metal zinc are correct?
30. What is the symbol of the metal used in the manufacture of aircraft because of its strength and low density?
31. Ammonia is manufactured using the Haber process. Which statement about this process is correct?
32. Iron can be protected from rusting by attaching a piece of a more reactive metal, e.g. magnesium, to the iron.
    Which equation represents the reaction that takes place?
33. Which row describes two uses of sulfur dioxide?
34. Part of the carbon cycle is shown.
35. The structures of four organic molecules are shown.
36. Which chemical equation for the substitution of an alkane with chlorine is correct?
37. Propene is an alkene that reacts with bromine, steam and hydrogen as shown.
38. The flow chart shows the preparation of ethanol and some important chemistry of ethanol.
39. Which statements about aqueous ethanoic acid are correct?
40. The structure of a polymer is shown.
    Which monomer forms this polymer?

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