Isomerism: structural isomerism and stereoisomerism: past paper questions
Real questions on isomerism: structural isomerism and stereoisomerism
The newest 20 of 81 written questions. Open one to see it on the real paper.
- 9701/41 · May/June 2026 · Q9a[3]
The structures of three amino acids, P, Q and R, are shown in Figure 9.1. P Q R NH 2 CH(CH 3 )COOH NH 2 C(CH 3 )CHCOOH NH 2 CH 2 COOH Figure 9.1 Two of the amino acids in Figure 9.1 show stereoisomerism. Draw the two stereoisomers of each of these amino acids in Figure 9.2. Name the type of stereoisomerism shown for ea...
See it on the paper → - 9701/21 · October/November 2025 · Q4b(ii)[2]
Define stereoisomerism.
See it on the paper → - 9701/21 · October/November 2025 · Q4b(iii)[3]
Draw a section of poly(propene), showing two repeat units. Use your diagram to identify the type of stereoisomerism shown by poly(propene). Explain your answer. section of poly(propene)
See it on the paper → - 9701/22 · October/November 2025 · Q3d(i)[2]
Complete Fig. 3.1 by drawing structures for C and D, the other two structural isomers of hexane.
See it on the paper → - 9701/42 · October/November 2025 · Q7a[2]
Only one of these seven compounds has stereoisomers. Draw three-dimensional diagrams of the two stereoisomers of this compound.
See it on the paper → - 9701/41 · May/June 2025 · Q6a(iii)[1]
In complex ion A, the carbon atom of each CN – ligand bonds to the Fe 3+ ion. State the type of bonding involved.
See it on the paper → - 9701/41 · May/June 2025 · Q6b[4]
Complex ions have different geometries. Complex ion A is octahedral. Ag + ions form a linear complex with ammonia. Ni atoms form a tetrahedral complex with carbon monoxide molecules. The carbon atom in the monodentate carbon monoxide ligand bonds to the nickel atom. Complete Fig. 6.1 to show the geometry of each of the...
See it on the paper → - 9701/22 · February/March 2025 · Q3d(iv)[1]
Identify the type of structural isomerism shown by the molecules in (d)(iii).
See it on the paper → - 9701/22 · February/March 2025 · Q3d(v)[2]
Explain why the two structural isomers do not form in equal amounts.
See it on the paper → - 9701/42 · February/March 2025 · Q6b(ii)[2]
U can act as a bidentate ligand. Explain what is meant by a bidentate ligand.
See it on the paper → - 9701/42 · February/March 2025 · Q6b(iii)[2]
Complete the three-dimensional diagrams in Fig. 6.3 to show both stereoisomers of [Cu(U) 3 ] 4– . Use O O O O to represent ligand U. Cu Cu Cu Cu
See it on the paper → - 9701/42 · February/March 2025 · Q6c(i)[1]
Identify the number of different carbon environments present in X. (i)
See it on the paper → - 9701/21 · October/November 2024 · Q1d(ii)[1]
Define stereoisomers.
See it on the paper → - 9701/21 · October/November 2024 · Q4a(ii)[1]
Explain why A does not show optical isomerism.
See it on the paper → - 9701/23 · October/November 2024 · Q1d(ii)[1]
Define stereoisomers.
See it on the paper → - 9701/23 · October/November 2024 · Q4a(ii)[1]
Explain why A does not show optical isomerism.
See it on the paper → - 9701/42 · October/November 2024 · Q8a[1]
Isomer P and isomer Q have identical physical and chemical properties, with the exception of two specific properties. One of these two properties is their differing effect on plane polarised light. State the other property by which they differ.
See it on the paper → - 9701/42 · October/November 2024 · Q8b[1]
Describe how a solution of pure isomer Q of the same concentration affects plane polarised light. (b) A solution of pure isomer P of a particular concentration rotates plane polarised light by 5.0° in a clockwise direction.
See it on the paper → - 9701/21 · May/June 2024 · Q6a(i)[1]
Explain what is meant by stereoisomerism.
See it on the paper → - 9701/21 · May/June 2024 · Q6a(ii)[2]
Deduce the number of stereoisomers of V. Explain your reasoning.
See it on the paper →
What examiners said
This was nearly always correctly answered, with or without reference to the structures given in 3(d)(iii).
— Examiner report, February/March 2025, 9701/22 Q3(d)(iv) (Cambridge)
Many extended answers were given here referencing the positive inductive effect of the alkyl groups but not related to a more stable secondary carbocation/intermediate. It was often suggested that the secondary halogenoalkane itself was more stable. Answers discussing the relative electronegativity of the halogens, or that the electrophile approaches with I(+) nearest were rarely seen.
— Examiner report, February/March 2025, 9701/22 Q3(d)(v) (Cambridge)
Many accurately-drawn correct answers were seen, using correct conventions for the three-dimensional bonds (wedged and dashed bonds). The most common errors were: • diagrams without any 3-D bonds • diagrams in which 3-D bonds were drawn but where the complex could not be octahedral as shown.
— Examiner report, February/March 2025, 9701/42 Q6(b)(iii) (Cambridge)
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