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CAIE IGCSE Chemistry Structural Isomerism

CAIE IGCSE Chemistry Structural Isomerism
Cambridge IGCSE Chemistry 0620 syllabus for exams in 2026, 2027 and 20282026–2028

Practise defining structural isomers and drawing distinct arrangements with the same molecular formula while preserving valencies and functional groups.

How this is tested

  • define structural isomers as compounds with the same molecular formula but different structures
  • verify an isomer pair by matching every atom count before comparing structural formulae
  • draw a different valid carbon skeleton or functional arrangement without changing the formula

Question 30

[Maximum number: 1]

Which structures represent a pair of structural isomers?
1CH3CH2CH2CH2CH2CH31 \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{3}2CH3CH2CH2CH2CH(CH3)22 \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}\left(\mathrm{CH}_{3}\right)_{2}3CH3CH(CH3)CH2CH2CH33 \mathrm{CH}_{3} \mathrm{CH}\left(\mathrm{CH}_{3}\right) \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{3}4CH3CH(CH3)CH2CH2CH2CH34 \mathrm{CH}_{3} \mathrm{CH}\left(\mathrm{CH}_{3}\right) \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{3}

A

1 and 2

B

1 and 3

C

2 and 4

D

3 and 4