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Secondary 3 Chemistry Periodic Table Quiz

Free Sec 3 Chemistry Periodic Table quiz, Gemma31B Exam version, with questions, answers, and O Level-style practice for Singapore students.

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Secondary 3 Chemistry From Real Exams Generated by Gemma 4 31B Updated 2026-08-17

Questions

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Answers

Answer Key - Secondary 3 Chemistry Quiz: Periodic Table

  1. The number of protons in the nucleus of an atom. [1]
  2. 35 [1]
  3. They have a full outer shell of electrons / stable octet [1], meaning they do not need to gain or lose electrons to achieve stability [1].
  4. 2 [1]
  5. Elements change from metallic to non-metallic character [1]; atomic radius generally decreases [1].
  6. (a) Alkali metals [1] (b) To prevent them from reacting with oxygen or water vapor in the air [1].
  7. Potassium [1].
  8. As you go down the group, the atomic radius increases [1]. The outer electron is further from the nucleus [1], resulting in a weaker electrostatic attraction between the nucleus and the outer electron, making it easier to lose [1].
  9. MX (where M is the Group 1 metal) [1].
  10. (a) Halogens [1] (b) Solid [1].
  11. To kill bacteria/microorganisms (disinfection) [1].
  12. As you go down the group, the atomic radius increases [1]. The outer shell is further from the nucleus [1], so the attraction between the nucleus and an incoming electron is weaker, making it harder to gain an electron [1].
  13. Any two: Form colored compounds [1]; Have variable oxidation states [1]; Act as catalysts [1].
  14. Iron [1].
  15. They have electrons in the d-orbitals [1] which are close in energy to the outer s-orbitals, allowing different numbers of electrons to be lost [1].
  16. (a) A list of metals arranged in order of their decreasing chemical reactivity [1]. (b) Magnesium [1].
  17. Sacrificial protection [1].
  18. A more reactive metal (e.g., zinc) is attached to the iron [1]. The more reactive metal oxidizes/corrodes preferentially [1], providing electrons to the iron to prevent it from forming ions/rusting [1].
  19. Galvanising involves coating the iron with a layer of zinc to provide a physical barrier [1], whereas sacrificial protection uses a more reactive metal block attached to the iron [1].
  20. No [1]. Silver is lower/less reactive than copper in the reactivity series and cannot displace it [1].