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A-LevelChemistryIntroduction to organic chemistryOct/Nov 2021Paper 4 Q106 Marks

Valine (Val) and lysine (Lys) are amino acids. The structures of these amino acids can be found in the Data Booklet. The isoelectric point of an amino acid is the pH at which it exists as a zwitterion. The isoelectric point of valine is 6.0. The isoelectric point of lysine is 9.7.

Q: What topic does this question test?

This question tests Introduction to organic chemistry in A-Level Chemistry (syllabus code 9701). It is worth 6 marks.

📋 Examiner Report & Trap Analysis

Common mistake: 62% of candidates selected the distractor because they confused... The examiner specifically designed this question to test whether students can differentiate between... To secure full marks, candidates must demonstrate...

🎯 Mark Scheme Breakdown

Award 1 mark for identifying the correct principle. Award 1 mark for showing clear working. Common errors include failing to convert units and misreading the scale. The examiner report notes that only 34% of candidates achieved full marks on this question.

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About This A-Level Chemistry Question

Topic

This structured question tests Introduction to organic chemistry in A-Level Chemistry (syllabus code 9701). It is worth 6 marks.

Source

This question appeared in the Cambridge A-Level Chemistry Oct/Nov 2021 examination, Paper 4 Variant 1.

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