AQA A-Level Chemistry Paper 3, 2021: Question 33
1 mark · Easy difficulty · Multiple Choice
This question tests your ability to recognise polymer structures, specifically those formed by condensation reactions between a dicarboxylic acid and a diamine. You need to identify the structure that contains the characteristic amide linkage (-CONH-) repeated along the chain, which defines a polyamide.
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Question text
33 Which is the repeating unit of a polyamide?
[1 mark]
A
B
C
D
Mark scheme
Show the mark scheme
33 D 1
How to answer it
Multiple Choice Explained: Which is the repeating unit of a polyamide?
Correct Answer: D
Why? Polyamides contain amide linkages (-CONH-) formed by condensation reactions between carboxylic acids (or acyl chlorides) and amines. Option D shows this characteristic amide bond in a repeating unit, making it the correct choice.
Why A is incorrect:
Option A shows a structure with an amine group, but no amide linkage is present. It resembles a monomer, not the repeating unit of a polyamide.
Why B is incorrect:
Option B shows a structure typical of an ester (–COO– group), not an amide. Esters are found in polyesters, not polyamides.
Why C is incorrect:
Although it contains both –CO– and –NH2 groups, Option C is not a repeating unit. It more closely resembles an intermediate monomer or an incomplete structure.
Topics
Organic Chemistry · 3.3.12 Polymers
Question and mark scheme from the AQA A-Level Chemistry examination, Paper 3, 2021. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.