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AS Level Chemistry MCQs with answers

Practise AS Level Chemistry (9701) with 427 exam-style MCQs, each with the answer and a short explanation. Every test is marked the moment you finish and shows your score chapter by chapter, so you know what to revise next. It is free and needs no sign-up.

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AS Level Chemistry MCQs with answers

Practise AS Level Chemistry (9701) with 427 exam-style MCQs, each with the answer and a short explanation. Every test is marked the moment you finish and shows your score chapter by chapter, so you know what to revise next. It is free and needs no sign-up.

427 questions · 22 chapters · 28 Cambridge past papers · 5 mock exams

What each chapter covers 22 chapters

The questions follow the syllabus chapter by chapter. You can test the whole subject or one chapter at a time.

  1. Atomic structure 34 questionsParticles in the atom and atomic radius, Isotopes, Electrons, energy levels and atomic orbitals, Ionisation energy
  2. Atoms, molecules and stoichiometry 33 questionsRelative masses of atoms and molecules, The mole and the Avogadro constant, Formulas, Reacting masses and volumes (of solutions and gases)
  3. Chemical bonding 59 questionsElectronegativity and bonding, Ionic bonding, Metallic bonding, Covalent bonding and coordinate (dative covalent) bonding, Shapes of molecules, Intermolecular forces, electronegativity and bond properties, Dot-and-cross diagrams
  4. States of matter 16 questionsThe gaseous state: ideal and real gases and pV = nRT, Bonding and structure
  5. Chemical energetics 17 questionsEnthalpy change, ΔH, Hess’s law
  6. Electrochemistry 8 questionsRedox processes: electron transfer and changes in oxidation number (oxidation state)
  7. Equilibria 20 questionsChemical equilibria: reversible reactions, dynamic equilibrium, Brønsted–Lowry theory of acids and bases
  8. Reaction kinetics 24 questionsRate of reaction, Effect of temperature on reaction rates and the concept of activation energy, Homogeneous and heterogeneous catalysts
  9. The Periodic Table: chemical periodicity 27 questionsPeriodicity of physical properties of the elements in Period 3, Periodicity of chemical properties of the elements in Period 3, Chemical periodicity of other elements
  10. Group 2 8 questionsSimilarities and trends in the properties of the Group 2 metals, magnesium to barium
  11. Group 17 32 questionsPhysical properties of the Group 17 elements, The chemical properties of the halogen elements and the hydrogen halides, Some reactions of the halide ions, The reactions of chlorine
  12. Nitrogen and sulfur 8 questions
  13. An introduction to AS Level organic chemistry 33 questionsFormulas, functional groups and the naming of organic compounds, Characteristic organic reactions, Shapes of organic molecules; σ and π bonds, Isomerism: structural isomerism and stereoisomerism
  14. Hydrocarbons 17 questionsAlkanes, Alkenes
  15. Halogen compounds 9 questionsHalogenoalkanes
  16. Hydroxy compounds 9 questionsAlcohols
  17. Carbonyl compounds 8 questionsAldehydes and ketones
  18. Carboxylic acids and derivatives 16 questionsCarboxylic acids, Esters
  19. Nitrogen compounds 16 questionsPrimary amines, Nitriles and hydroxynitriles
  20. Polymerisation 8 questionsAddition polymerisation
  21. Organic synthesis 8 questions
  22. Analytical techniques 17 questionsInfrared spectroscopy, Mass spectrometry
Sample AS Level Chemistry MCQs with answers 12 questions

12 questions from the test, one or two from each chapter. Try each one, then open the answer.

1. Why is the second ionisation energy of an element always greater than its first?

  1. A
    the second electron is always removed from an inner shell
  2. B
    the second electron is removed from a positive ion, in which the same nuclear charge attracts fewer electrons
  3. C
    the nuclear charge increases after the first electron is removed
  4. D
    the second electron is always in a higher-energy sub-shell
Show answer

Answer: B. After one electron has gone, the same number of protons holds fewer electrons, repulsion is less and the ion is smaller, so more energy is needed. The second electron is not always from an inner shell (for magnesium both come from 3s).

2. What is the mass of one atom of carbon-12? (L = 6.02 × 1023 mol−1)

  1. A
    1.99 × 10−23 g
  2. B
    1.66 × 10−24 g
  3. C
    7.22 × 1024 g
  4. D
    12.0 g
Show answer

Answer: A. One mole of carbon-12 (12.0 g) contains 6.02 × 1023 atoms, so one atom has a mass of 12.0 ÷ (6.02 × 1023) = 1.99 × 10−23 g. 1.66 × 10−24 g is the mass of 1 u.

3. Propanone (Mr 58) boils at 56 °C but butane (Mr 58) boils at −1 °C. What is the main reason?

  1. A
    propanone forms hydrogen bonds between its molecules
  2. B
    propanone molecules have a permanent dipole, so permanent dipole–permanent dipole forces act in addition to id-id forces
  3. C
    butane has weaker covalent bonds
  4. D
    propanone has more electrons than butane
Show answer

Answer: B. The polar C=O group gives propanone a permanent dipole. Propanone has no O–H or N–H, so it cannot hydrogen bond with itself; both molecules have the same number of electrons, so id-id forces are similar.

4. Why does solid sodium chloride not conduct electricity, although molten sodium chloride does?

  1. A
    in the solid the ions are held in fixed positions; in the melt they are free to move
  2. B
    the solid has no delocalised electrons, but the melt does
  3. C
    the solid contains molecules, but the melt contains ions
  4. D
    electrons can move only when the ions are hot
Show answer

Answer: A. Ionic compounds conduct by movement of ions. In the solid lattice the ions cannot move; melting frees them to carry charge. There are no delocalised electrons in either state.

5. A reaction is exothermic when

  1. A
    more energy is absorbed in breaking bonds than is released in making bonds
  2. B
    the energy released in forming the new bonds exceeds the energy needed to break the old bonds
  3. C
    the activation energy is zero
  4. D
    the products have higher enthalpy than the reactants
Show answer

Answer: B. Breaking bonds always absorbs energy and forming bonds releases it. If more is released than absorbed, the surroundings get warmer and ΔH is negative.

6. What is the systematic name of NaClO?

  1. A
    sodium chlorate(V)
  2. B
    sodium chloride(I)
  3. C
    sodium chlorite
  4. D
    sodium chlorate(I)
Show answer

Answer: D. In ClO− oxygen is −2, so chlorine is +1: chlorate(I). NaClO3 is sodium chlorate(V). The Roman numeral gives the oxidation number of chlorine.

7. An equilibrium mixture contains 2.0 mol of N2, 6.0 mol of H2 and 2.0 mol of NH3 at a total pressure of 200 kPa. What is the partial pressure of hydrogen?

  1. A
    60 kPa
  2. B
    150 kPa
  3. C
    40 kPa
  4. D
    120 kPa
Show answer

Answer: D. Total amount = 10.0 mol, so the mole fraction of H2 = 6.0/10.0 = 0.60. Partial pressure = mole fraction × total pressure = 0.60 × 200 = 120 kPa.

8. The concentration of a reactant falls from 0.800 mol dm−3 to 0.500 mol dm−3 in 2.0 minutes. What is the average rate of reaction in mol dm−3 s−1?

  1. A
    2.5 × 10−3
  2. B
    4.2 × 10−3
  3. C
    0.15
  4. D
    6.7 × 10−3
Show answer

Answer: A. Change in concentration = 0.300 mol dm−3 over 120 s. Rate = 0.300 ÷ 120 = 2.5 × 10−3 mol dm−3 s−1. 0.15 forgets to convert minutes into seconds.

9. Why is the radius of the P3− ion much larger than that of the Al3+ ion?

  1. A
    P3− has a greater nuclear charge
  2. B
    phosphorus is a non-metal
  3. C
    Al3+ has more electrons than P3−
  4. D
    P3− has three occupied electron shells, while Al3+ has only two
Show answer

Answer: D. Al3+ has lost its third shell (2,8), whereas P3− has gained electrons into it (2,8,8). The extra shell outweighs the larger nuclear charge of phosphorus.

10. Which equation shows the thermal decomposition of calcium nitrate?

  1. A
    Ca(NO3)2 → Ca(NO2)2 + O2
  2. B
    2Ca(NO3)2 → 2CaO + 4NO + 3O2
  3. C
    Ca(NO3)2 → CaO + 2NO2 + O2
  4. D
    2Ca(NO3)2 → 2CaO + 4NO2 + O2
Show answer

Answer: D. Group 2 nitrates decompose to the oxide, brown nitrogen dioxide and oxygen. O atoms: 12 on the left and 2 + 8 + 2 = 12 on the right. Ca(NO3)2 → CaO + 2NO2 + O2 has 7 O on the right, and forming a nitrite is not Group 2 behaviour.

11. What are the products when chlorine reacts with hot concentrated aqueous sodium hydroxide?

  1. A
    NaCl, NaClO and H2O
  2. B
    NaCl and H2O only
  3. C
    NaClO3, H2 and O2
  4. D
    NaCl, NaClO3 and H2O
Show answer

Answer: D. In hot alkali the chlorate(I) that forms disproportionates further, so the products are sodium chloride, sodium chlorate(V), NaClO3, and water.

12. Peroxyacetyl nitrate (PAN), a component of photochemical smog, is formed from

  1. A
    nitrogen oxides and unburned hydrocarbons in sunlight
  2. B
    sulfur dioxide and water vapour
  3. C
    carbon monoxide and ozone
  4. D
    ammonia and nitric acid
Show answer

Answer: A. NO and NO2 from vehicle exhausts react with unburned hydrocarbons under the action of sunlight to produce PAN, an eye and lung irritant found in smog over cities.

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Ways to practise 7 ways

When you get a question wrong, a short note called "The idea behind this" explains the topic it belongs to, with the rules to remember and a worked example.

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Yes. Every test and every explanation is free, and you do not need an account. If you sign in, your results are kept across your devices.

Are these past paper questions?

The 427 MCQs are our own, written to the syllabus in the style of the exam. The 28 Cambridge past papers are listed separately inside the test.

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Instantly. You get your score, the right answer and an explanation for every question, and a list of the topics to work on.

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