National 5 (Scotland) · National 5 Chemistry

Chemistry in Society

23 practice questions, each with the answer and an explanation.

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Random questions from this topic, one at a time. You see the answer and the explanation straight after each one.

All 23 questions

  1. Zinc is added to copper sulfate solution. What do you expect to observe and why?
  2. In an electrochemical cell magnesium and copper electrodes are joined by wires. In which direction do electrons flow?
  3. What is the purpose of an ion bridge in an electrochemical cell?
  4. Magnesium atoms change to magnesium ions: Mg → Mg²⁺ + 2e⁻. Which statement is correct?
  5. Why does zinc coating protect an iron nail from rusting even when the coating is scratched?
  6. Which two substances are needed for iron to rust?
  7. Which feature of a monomer allows it to undergo addition polymerisation?
  8. A radioactive isotope has a half-life of 6 hours. How much of a 80 g sample remains after 18 hours?
  9. In paper chromatography, why do different substances move different distances?
  10. A compound is made of calcium and chlorine. What is its formula?
  11. What is the formula of sodium sulfate? (Sulfate is SO₄²⁻; sodium forms Na⁺.)
  12. Why do covalent molecular substances such as methane have low melting points?
  13. Which gas is produced when magnesium reacts with dilute hydrochloric acid, and how is it tested?
  14. How is aluminium extracted from its ore?
  15. Iron ore is reduced in a blast furnace. Which substance acts as the reducing agent?
  16. What mass of calcium carbonate (GFM 100) is needed to make 2.2 g of carbon dioxide (GFM 44) by CaCO₃ → CaO + CO₂?
  17. Sulfuric acid reacts with sodium hydroxide: H₂SO₄ + 2NaOH → Na₂SO₄ + 2H₂O. What volume of 0.50 mol/l sodium hydroxide neutralises 25 cm³ of 0.20 mol/l sulfuric acid?
  18. What mass of magnesium (GFM 24) reacts completely with 100 cm³ of 1.0 mol/l hydrochloric acid in Mg + 2HCl → MgCl₂ + H₂?
  19. What is the percentage by mass of nitrogen in ammonium nitrate, NH₄NO₃? (H = 1, N = 14, O = 16)
  20. Two hydrocarbons both have the formula C₄H₈. One decolourises bromine water and the other does not. What is the best explanation?
  21. The same excess of dilute acid is added to equal masses of marble chips. In experiment 1 the acid is 1 mol/l and in experiment 2 it is 2 mol/l. Which statement is correct?
  22. Magnesium–copper and zinc–copper cells are set up in the same way. Which statement about the voltages is correct?
  23. The activity of a radioactive sample falls from 640 counts per minute to 80 counts per minute in 15 days. What is the half-life?

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