O Level / IGCSE Chemistry chapter 8: The Periodic Table MCQs with answers

By Team Megalecture · Updated 4 Nov 2026

111 exam-style questions on The Periodic Table, each with the answer and a short explanation. Ten of them are below to try. The chapter test draws ten fresh questions each time and is marked the moment you finish, with your score by topic.

111 questions · 5 topics · 10 per test

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What chapter 8 covers

Ten The Periodic Table questions with answers

Try each one, then open the answer. These ten stay the same; the test draws new ones every time.

1. Which statement describes the change going down Group VII from chlorine to iodine?

  1. A
    density decreases and reactivity increases
  2. B
    density and reactivity both increase
  3. C
    density increases and reactivity decreases
  4. D
    the elements change from diatomic to monatomic
Show answer

Answer: C. The halogens become denser and less reactive down the group. All exist as diatomic molecules: Cl2, Br2, I2.

2. An element Y has the electronic configuration 2,8,1. Which element is most likely to have similar chemical properties to Y?

  1. A
    an element with configuration 2,8,2
  2. B
    an element with configuration 2,8,3
  3. C
    an element with configuration 2,8,8
  4. D
    an element with configuration 2,8,8,1
Show answer

Answer: D. Elements in the same group have the same number of outer-shell electrons, and it is the outer electrons that decide chemical properties. 2,8,8,1 has one outer electron, like 2,8,1, so both are in Group I.

3. Aqueous bromine is added to aqueous potassium iodide. What colour change is seen?

  1. A
    colourless to orange
  2. B
    orange to brown
  3. C
    orange to colourless
  4. D
    no change
Show answer

Answer: B. Bromine is more reactive than iodine, so it displaces iodine: Br2 + 2I− → 2Br− + I2. The orange bromine is replaced by brown iodine in solution.

4. Compared with sodium, a typical transition element has

  1. A
    a lower density, a higher melting point and white compounds
  2. B
    a lower density, a lower melting point and white compounds
  3. C
    a higher density, a higher melting point and coloured compounds
  4. D
    a higher density, a lower melting point and white compounds
Show answer

Answer: C. Transition elements are hard, dense metals with high melting points. Sodium is soft, floats on water and melts below 100 °C.

5. Why are lithium, sodium and potassium stored under oil?

  1. A
    to stop them reacting with oxygen and water vapour in the air
  2. B
    to keep the metals soft so that they can still be cut easily
  3. C
    to stop them evaporating
  4. D
    to stop them melting
Show answer

Answer: A. The alkali metals are very reactive and quickly tarnish or react in moist air. The oil keeps air and water away.

6. Which statement about the Group I metals is correct as you go down the group?

  1. A
    they become less reactive and have higher melting points
  2. B
    they become less dense
  3. C
    their outer electrons become harder to lose
  4. D
    they become more reactive and have lower melting points
Show answer

Answer: D. Down Group I the outer electron is further from the nucleus and more easily lost, so reactivity rises; melting points fall.

7. Francium is at the bottom of Group I. Which prediction about francium is most likely to be correct?

  1. A
    it reacts more vigorously with water than caesium and forms FrOH
  2. B
    it reacts more slowly with water than caesium and forms FrOH
  3. C
    it reacts more vigorously with water than caesium and forms Fr(OH)2
  4. D
    it does not react with water because it is so dense
Show answer

Answer: A. Reactivity increases down Group I, so francium should be the most reactive. With one outer electron it forms Fr+, so the hydroxide is FrOH.

8. What is the oxidation number of chromium in the dichromate(VI) ion, Cr2O72−?

  1. A
    +3
  2. B
    +6
  3. C
    +7
  4. D
    +12
Show answer

Answer: B. Seven O atoms give −14. The ion has an overall charge of −2, so the two Cr atoms together are +12, which is +6 each. +12 forgets to share between the two Cr atoms.

9. Tungsten is a transition element. Which use of tungsten depends mainly on its very high melting point?

  1. A
    as the glowing filament in an old-style light bulb
  2. B
    in compounds that colour glass
  3. C
    as a catalyst in the chemical industry
  4. D
    as a coating to stop iron rusting
Show answer

Answer: A. A filament must glow white-hot without melting, which needs a very high melting point (over 3400 °C for tungsten). The other uses depend on colour, catalytic activity or reactivity.

10. Why does the reactivity of the Group I metals increase down the group?

  1. A
    the outer electron is further from the nucleus, so it is lost more easily
  2. B
    the atoms have more electrons in the outer shell
  3. C
    the atoms gain an electron more easily
  4. D
    the nucleus has more protons, so it holds the outer electron more strongly
Show answer

Answer: A. All Group I atoms have one outer electron. Down the group it is in a shell further from the nucleus and is attracted less strongly, so it is lost more easily in reactions.

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Ways to practise this chapter

The Periodic Table: questions students ask

How many The Periodic Table MCQs are there?

111, each with the answer and a short explanation, across 5 topics: Arrangement of elements, Group I properties, Group VII properties, Transition elements, Noble gases. Every chapter test draws ten of them, so you can take it many times.

Is the O Level / IGCSE Chemistry chapter 8 test free?

Yes. The test, the answers and the explanations are free and need no sign-up. Sign in only if you want your scores kept across devices.

How is the chapter test marked?

The moment you press Finish: your score, the right answer and an explanation for every question, and the ones you got wrong saved in My mistakes to retry.

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