IGCSE Chemistry 2021 0620/23 Oct/Nov

IGCSE 2021 0620/23 Oct/Nov (pdf)

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1. Brownian motion and the diffusion of gases provide evidence for the particulate nature of matter. Which row identifies an example of Brownian motion and how molecular mass determines the rate of diffusion of gas molecules?
   
2. A student put exactly 25.00 cm³ of dilute hydrochloric acid into a conical flask. The student added 2.5 g of solid sodium carbonate and measured the change in temperature of the mixture.
   Which apparatus does the student need to use?
3. A student separates sugar from pieces of broken glass by dissolving the sugar in water and filtering off the broken glass.
4. The nucleus of a particular atom consists of nineteen particles.
   Nine of them are positively charged and ten of them are uncharged.
   Which statement about this nucleus is correct?
5. Which description of brass is correct?
6. A Group I element combines with a Group VII element and forms an ionic bond.
   Which row shows how the electronic structures change?
7. Which statement describes the attractive forces between molecules?
8. Which diagram shows the outer electron arrangement in a molecule of carbon dioxide?
9. Aluminium oxide is an ionic compound containing Al3+ ions and O2– ions.
   Aluminium hydroxide is an ionic compound containing Al3+ ions and OH– ions.
   In which row are the formulae for aluminium oxide and aluminium hydroxide correct?
10. Effervescence is observed at the negative electrode (cathode) during the electrolysis of concentrated aqueous sodium chloride.
    Which element is produced at the negative electrode (cathode)?

11. The energy level diagram for a chemical reaction is shown.
12. Chlorine reacts with ethane to produce chloroethane and hydrogen chloride.
13. What is the concentration of the solution when 31.8 g of sodium carbonate, Na2CO3, is dissolved in water to make a solution of 250 cm³?
14. A fuel cell is used to generate electricity.
    Which chemicals are used in a fuel cell?
15. Sulfuric acid is manufactured using the Contact process. One of the reactions is shown.
16. Iron(II) chloride solution reacts with chlorine gas
17. Excess dilute hydrochloric acid is added to equal masses of powdered calcium carbonate in two separate experiments.
    Two different concentrations of hydrochloric acid are used. The temperature in both experiments is the same.
    The results show the change in mass of the reaction flask measured over time.
18. Basic oxides are neutralised by acidic oxides.
    Which element forms an oxide that neutralises calcium oxide?
19. Four solid oxides are added to dilute hydrochloric acid and aqueous sodium hydroxide.
    Which row describes an amphoteric oxide?
20. Which row describes an acid and an oxidising agent?
21. A period of the Periodic Table is shown.
22. Part of the Periodic Table is shown.
23. Which property is shown by transition metals but not shown by Group I metals?
24. The noble gases are in Group VIII of the Periodic Table.
    Which statement explains why noble gases are unreactive?
25. Which statement is correct for all metals?
26. Chromium is a more reactive metal than iron but less reactive than zinc.
    Which statements are correct?
27. Aluminium objects do not need protection from corrosion.
    Iron objects must be protected from corrosion.
    Which statement explains why aluminium resists corrosion?
28. Which statement describes how oxides of nitrogen are formed in a car engine?
29. Ships are made of steel, an alloy of iron.
    Blocks of magnesium are attached to the underside of ships to prevent rusting.
    Which statement explains how the magnesium prevents rusting?
30. Which process is used to produce hydrogen for the Haber process?
31. One of the steps in manufacturing sulfuric acid in the Contact process is shown.
32. Lime (calcium oxide) is used to treat waste water from a factory.
    Which substance is removed by the lime?
33. What is the structure of propanol?
34. Fuel X produces carbon dioxide and water when it is burned in air. So does fuel Y.
    What could X and Y be?
35. What is the main constituent of natural gas?
36. Which statement describes the members of a homologous series?
37. The structures of two compounds are shown
38. Some reactions of substance Q are shown
39. Proteins and starch are natural polymers.
    Which row identifies the method of polymerisation of proteins and starch?
40. The diagram shows the partial structure of Terylene.

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