MDCAT Chemistry chapter 11: Chemistry · s and p block elements MCQs with answers

By Team Megalecture · Updated 4 Nov 2026

61 exam-style questions on Chemistry · s and p block elements, 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.

61 questions · 2 topics · 10 per test

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What chapter 11 covers

Ten Chemistry · s and p block elements questions with answers

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

1. Which alkali metal hydroxide is the least soluble in water?

  1. A
    LiOH
  2. B
    NaOH
  3. C
    KOH
  4. D
    CsOH
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Answer: A. Solubility of the group 1 hydroxides increases down the group, so LiOH is the least soluble: the small Li+ and OH− ions form a lattice with a very high lattice energy.

2. Which group 2 sulphate is the least soluble in water?

  1. A
    SrSO4
  2. B
    BaSO4
  3. C
    CaSO4
  4. D
    MgSO4
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Answer: B. The solubility of group 2 sulphates decreases down the group: MgSO4 (Epsom salt) is very soluble, CaSO4 is sparingly soluble and BaSO4 is so insoluble that it is safely swallowed for barium-meal X-rays.

3. Aluminium lies high in the electrochemical series, yet aluminium pans are not corroded by air or boiling water. This is because

  1. A
    aluminium has metallic bonds too strong for water to break
  2. B
    aluminium forms a soluble hydroxide that is washed away
  3. C
    aluminium has a very high first ionisation energy
  4. D
    a thin, firmly attached oxide film protects the metal
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Answer: D. In air, aluminium is at once covered by a thin, non-porous layer of Al2O3 that sticks to the metal and stops further attack; anodising thickens this layer on purpose. Without the film, the reactive metal would be attacked by water.

4. Which sequence of period 3 elements shows decreasing electrical conductivity?

  1. A
    sulphur > silicon > sodium
  2. B
    silicon > sodium > sulphur
  3. C
    sodium > silicon > sulphur
  4. D
    sodium > sulphur > silicon
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Answer: C. Sodium is a metal and the best conductor, silicon is a semiconductor with a small conductivity, and sulphur, made of S8 molecules with no mobile electrons, is an insulator.

5. The first ionisation energy of calcium is the energy needed for which process?

  1. A
    Ca(s) → Ca+(g) + e−
  2. B
    Ca(g) → Ca2+(g) + 2e−
  3. C
    Ca(g) → Ca+(g) + e−
  4. D
    Ca(g) + e− → Ca−(g)
Show answer

Answer: C. First ionisation energy is the energy needed to remove one mole of electrons from one mole of isolated gaseous atoms, forming gaseous 1+ ions; its unit is kJ mol−1. Starting from the solid adds the atomisation energy, losing two electrons needs the first and second ionisation energies together, and gaining an electron is electron affinity.

6. Which hydrogen halide is the weakest acid in aqueous solution?

  1. A
    HF
  2. B
    HCl
  3. C
    HBr
  4. D
    HI
Show answer

Answer: A. The H–F bond is the shortest and strongest of the hydrogen halides, so HF ionises least in water. Acid strength rises HF < HCl < HBr < HI as the H–X bond gets weaker down the group.

7. Unlike calcium, strontium and barium, the metals beryllium and magnesium give no colour in a flame test. This is because

  1. A
    they have no electrons at all in their outermost s subshell
  2. B
    their excited electrons fall back without emitting any energy
  3. C
    their atoms are too large for the flame energy to excite their electrons
  4. D
    their electrons are held so firmly that the flame cannot excite them
Show answer

Answer: D. Be and Mg have the smallest atoms and highest ionisation energies in the group, so the energy of a Bunsen flame cannot promote their outer electrons to higher levels, and no visible light is emitted. The larger Ca, Sr and Ba atoms are excited easily and give brick-red, crimson and apple-green flames.

8. Which oxide of a period 3 element is amphoteric, reacting with both acids and alkalis?

  1. A
    MgO
  2. B
    SiO2
  3. C
    Al2O3
  4. D
    P4O10
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Answer: C. Al2O3 reacts with HCl to give AlCl3 and with NaOH to give sodium aluminate. MgO is basic, while SiO2 and P4O10 are acidic.

9. How many elements are there in the fourth period of the periodic table, and which subshells are filled across it?

  1. A
    18; the 4s, 3d and 4p subshells
  2. B
    8; the 4s and 4p subshells only
  3. C
    18; the 4s, 4p and 4d subshells
  4. D
    32; the 4s, 4p, 4d and 4f subshells
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Answer: A. Period 4 starts as the fourth shell begins (potassium, 4s1) and ends at krypton. On the way the 3d subshell fills after 4s, adding ten transition elements, so 2 + 10 + 6 = 18; the 4d and 4f subshells fill only in periods 5 and 6.

10. A magnesium ribbon left in air for some weeks turns dull, and then at first reacts with dilute acid more slowly than a freshly cleaned ribbon. Why?

  1. A
    a thin oxide film on its surface keeps the acid off the metal
  2. B
    the magnesium has changed into a less reactive allotrope
  3. C
    nitrogen from the air has changed all of it into magnesium nitride
  4. D
    the dull metal has lost electrons and become positively charged
Show answer

Answer: A. Like beryllium and aluminium, magnesium gains a thin protective oxide layer in air, and the acid must dissolve this before it reaches the metal. Rubbing the ribbon with sandpaper removes the film, which is why it is cleaned before use.

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Chemistry · s and p block elements: questions students ask

How many Chemistry · s and p block elements MCQs are there?

61, each with the answer and a short explanation, across 2 topics: Periodic trends and the s block, The p block. Every chapter test draws ten of them, so you can take it many times.

Is the MDCAT Chemistry chapter 11 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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