Isomerism: structural isomerism and stereoisomerism: past paper questions

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• Question 25May/June 2026, paper 11Multiple choice1 markHas a diagram

  The formula of 11-cis-retinal is ${\text{C}}_{20}{\text{H}}_{28}\text{O}$. The structure of 11-cis-retinal consists of a cyclohexene ring and a long aliphatic side chain ending in an aldehyde group. The long aliphatic side chain contains one or more $\text{C}=\text{C}$ bonds.

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• Question 25Oct/Nov 2025, paper 11Multiple choice1 markHas a diagram

  The diagrams show skeletal formulas of some isomers of ${\text{C}}_6{\text{H}}_{12}\text{O}$.

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• Question 27Oct/Nov 2024, paper 11Multiple choice1 markHas a diagram

  Geraniol and nerol are isomers of each other. Which type of isomerism is shown here?

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• Question 26Oct/Nov 2023, paper 11Multiple choice1 markHas a diagram

  The compound aspartame is widely used as a sweetener in ‘diet’ soft drinks. Aspartame is chiral. (There are no chiral carbon atoms in ${\mathrm{C}}_6{\mathrm{H}}_5$.) How many chiral carbon atoms are present in a molecule of aspartame?

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• Question 27May/June 2026, paper 11Multiple choice1 markHas a diagram

  The structure of an ether X is shown. The $\text{C}-\text{O}-\text{C}$ group is the functional group in the homologous series of ethers.

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• Question 26Oct/Nov 2025, paper 11Multiple choice1 markHas a diagram

  The skeletal formulas of two compounds are shown. progesterone and testosterone Which statements about progesterone and testosterone are correct?

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• Question 28Oct/Nov 2024, paper 11Multiple choice1 mark

  Which compound has the greatest number of stereoisomers?

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• Question 27Oct/Nov 2023, paper 12Multiple choice1 markHas a diagram

  Artemisinin is a powerful anti-malarial drug. How many chiral centres are there in each molecule of artemisinin?

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• Question 31May/June 2026, paper 11Multiple choice1 mark

  Structural isomerism and stereoisomerism should be taken into account when answering this question.

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• Question 26Oct/Nov 2025, paper 12Multiple choice1 markHas a diagram

  The structure of disodium cromoglycate is shown. How many chiral centres are there in this molecule?

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• Question 36Oct/Nov 2024, paper 11Multiple choice1 mark

  Which compound, on reaction with hydrogen cyanide, produces a compound with a chiral centre?

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• Question 29Oct/Nov 2023, paper 12Multiple choice1 mark

  How many geometrical (cis/trans) isomers are there of hex-2,4-diene, ${\text{CH}}_3{\text{CH=CHCH=CHCH}}_3$?

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• Question 25May/June 2026, paper 12Multiple choice1 mark

  What is the least number of carbon atoms in a non-cyclic alkane molecule that has a chiral centre?

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• Question 26Oct/Nov 2024, paper 12Multiple choice1 mark

  Compound X is found in cell walls of some bacteria. Its structural formula is shown.

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• Question 38Oct/Nov 2023, paper 12Multiple choice1 mark

  How many esters with the molecular formula ${\text{C}}_5{\text{H}}_{10}{\text{O}}_2$ can be made by reacting a primary alcohol with a carboxylic acid?

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• Question 27May/June 2026, paper 12Multiple choice1 mark

  Structural isomerism and stereoisomerism should be considered when answering this question. Several isomers with molecular formula ${\text{C}}_5{\text{H}}_{10}\text{O}$ give an orange precipitate with 2,4-DNPH reagent.

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• Question 26Oct/Nov 2025, paper 13Multiple choice1 markHas a diagram

  The skeletal formulas of two compounds are shown. progesterone [skeletal formula of progesterone] testosterone [skeletal formula of testosterone] Which statements about progesterone and testosterone are correct?

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• Question 27Oct/Nov 2024, paper 12Multiple choice1 mark

  Structural isomerism only should be considered when answering this question. How many straight-chain isomers are there with molecular formula ${\mathrm{C}}_4{\mathrm{H}}_8{\mathrm{C}\mathrm{l}}_2$?

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• Question 26Oct/Nov 2023, paper 13Multiple choice1 markHas a diagram

  The compound aspartame is widely used as a sweetener in 'diet' soft drinks. Aspartame is chiral. (There are no chiral carbon atoms in ${\text{C}}_6{\text{H}}_5$.) How many chiral carbon atoms are present in a molecule of aspartame?

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• Question 39May/June 2026, paper 12Multiple choice1 mark

  Structural isomerism and stereoisomerism should be considered when answering this question.

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• Question 3Oct/Nov 2025, paper 22Structured14 marksHas a diagram

  The alkanes are a homologous series of organic molecules. Alkanes are generally unreactive and are commonly used as fuels. Define homologous series.

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• Question 32Oct/Nov 2024, paper 12Multiple choice1 markHas a diagram

  What are the only structures formed when butan-2-ol is heated with concentrated ${\mathrm{H}}_2{\mathrm{S}\mathrm{O}}_4$?

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• Question 26May/June 2026, paper 13Multiple choice1 markHas a diagram

  A student looks at the structure of chloroethene and of poly(chloroethene) and draws two conclusions. 1 The carbon atoms are ${\text{sp}}^3$ hybridised in each substance. 2 Chloroethene and poly(chloroethene) contain chiral carbon atoms.

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• Question 30May/June 2025, paper 11Multiple choice1 mark

  Structural isomerism and stereoisomerism should be considered when answering this question. 2,5-dibromohexane is heated under reflux with ethanolic KOH. How many isomeric compounds are formed with molecular formula ${\text{C}}_6{\text{H}}_{10}$?

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• Question 27Oct/Nov 2024, paper 13Multiple choice1 markHas a diagram

  Geraniol and nerol are isomers of each other. [Diagram of geraniol and nerol] Which type of isomerism is shown here?

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• Question 29May/June 2026, paper 13Multiple choice1 markHas a diagram

  Structural isomerism and stereoisomerism should be taken into account when answering this question. Two compounds, X and Y, both have the molecular formula ${\text{C}}_5{\text{H}}_{11}\text{Br}$.

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• Question 31May/June 2025, paper 11Multiple choice1 markHas a diagram

  Considering only structural isomers, what is the number of alcohols of each type with the formula ${\text{C}}_5{\text{H}}_{12}\text{O}$?

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• Question 24May/June 2023, paper 11Multiple choice1 mark

  Structural isomerism and stereoisomerism should be considered when answering this question. If a molecule contains two non-identical chiral carbon atoms, four optical isomers exist.

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• Question 6May/June 2026, paper 22Structured13 marksHas a diagram

  Figure 6.1 shows the structure of compound P. Draw the structure of the stereoisomer of P.

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• Question 38May/June 2025, paper 11Multiple choice1 markHas a diagram

  The structure of the testosterone molecule is shown. Which statements are correct?

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