O Level / IGCSE Chemistry chapter 11: Organic chemistry MCQs with answers

By Team Megalecture · Updated 4 Nov 2026

184 exam-style questions on Organic chemistry, 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.

184 questions · 8 topics · 10 per test

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What chapter 11 covers

Ten Organic chemistry questions with answers

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

1. Ethanol burns completely: C2H5OH + 3O2 → 2CO2 + 3H2O. What volume of oxygen, at room temperature and pressure, is needed to burn 0.10 mol of ethanol? (molar gas volume 24 dm3)

  1. A
    2.4 dm3
  2. B
    4.8 dm3
  3. C
    7.2 dm3
  4. D
    9.6 dm3
Show answer

Answer: C. 0.10 mol ethanol needs 3 × 0.10 = 0.30 mol O2; 0.30 × 24 = 7.2 dm3. 4.8 dm3 is the volume of carbon dioxide produced, not of oxygen used.

2. Why is CH3CH2OH a more useful formula for ethanol than C2H6O?

  1. A
    it shows how the atoms are arranged, while C2H6O could describe more than one compound
  2. B
    it shows the relative molecular mass, which C2H6O does not
  3. C
    it shows the simplest whole-number ratio of the atoms
  4. D
    it shows the three-dimensional shape and the bond angles of the molecule
Show answer

Answer: A. A structural formula is unambiguous: C2H6O fits more than one arrangement of atoms, but CH3CH2OH fits only ethanol. Both give the same Mr.

3. Which statement about PET is correct?

  1. A
    it can be converted back into its monomers and re-polymerised
  2. B
    it is a polyamide, with amide linkages between the monomers
  3. C
    it is an addition polymer made from ethene
  4. D
    it can never be recycled, so it must be buried in landfill
Show answer

Answer: A. PET is a polyester. It can be broken down into its monomers, which are then used to make new PET.

4. A compound has the molecular formula C5H10 and an unbranched chain. Using the general formulae of the homologous series, to which series does it belong?

  1. A
    alkanes
  2. B
    alkenes
  3. C
    alcohols
  4. D
    carboxylic acids
Show answer

Answer: B. C5H10 fits CnH2n with n = 5, the general formula of the alkenes. An alkane with five carbons would be C5H12.

5. Propene, CH3CH=CH2, reacts with bromine. What is the structural formula of the product?

  1. A
    CH3CH2CH2Br
  2. B
    CH3CHBrCH2Br
  3. C
    CH2BrCH2CH2Br
  4. D
    CH3CBr2CH3
Show answer

Answer: B. One Br atom adds to each carbon of the C=C bond, giving CH3CHBrCH2Br (1,2-dibromopropane). The Br atoms do not go to the end carbons or onto one carbon.

6. Waste poly(chloroethene), PVC, is burned in an open fire. Which toxic gas containing chlorine is released?

  1. A
    carbon monoxide
  2. B
    hydrogen chloride
  3. C
    nitrogen dioxide
  4. D
    sulfur dioxide
Show answer

Answer: B. PVC contains chlorine atoms, so burning it releases hydrogen chloride, which is toxic and forms an acidic solution. Carbon monoxide may also form, but it contains no chlorine.

7. Which fraction is used mainly to make other chemicals rather than being burned as a fuel?

  1. A
    naphtha
  2. B
    refinery gas
  3. C
    diesel oil
  4. D
    fuel oil
Show answer

Answer: A. Naphtha is the chemical feedstock fraction. Refinery gas, diesel oil and fuel oil are all burned as fuels.

8. The gas given off from a fermenting glucose solution is bubbled through limewater. What is seen, and which gas is present?

  1. A
    limewater stays colourless; oxygen
  2. B
    limewater turns milky; hydrogen
  3. C
    limewater stays colourless; carbon dioxide
  4. D
    limewater turns milky; carbon dioxide
Show answer

Answer: D. Fermentation gives ethanol and carbon dioxide, and carbon dioxide turns limewater milky (cloudy).

9. Which pair of monomers can react to form a polyester?

  1. A
    a dicarboxylic acid and a diamine
  2. B
    an alkane and chlorine
  3. C
    ethene and propene
  4. D
    a dicarboxylic acid and a diol
Show answer

Answer: D. A diol has an –OH at each end, which forms ester links with the –COOH groups. A diamine would form amide links, giving a polyamide.

10. Ethanoic acid reacts with ethanol in the presence of concentrated sulfuric acid. What type of compound is formed?

  1. A
    an alkene
  2. B
    an alcohol
  3. C
    a polymer
  4. D
    an ester
Show answer

Answer: D. Carboxylic acid + alcohol → ester + water (esterification). The product is ethyl ethanoate, a sweet-smelling liquid.

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How many Organic chemistry MCQs are there?

184, each with the answer and a short explanation, across 8 topics: Formulae, functional groups and terminology, Naming organic compounds, Fuels, Alkanes, Alkenes, Alcohols, Carboxylic acids, Polymers. Every chapter test draws ten of them, so you can take it many times.

Is the O Level / IGCSE 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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