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A-LevelChemistryOrganic synthesis9701/12 · Feb/Mar 2021 · Q271 Mark

In this question you can assume that ¹H and ³H have the same chemical properties. A sample of ethanal contains only one isotope of hydrogen, ¹H. It is reduced to compound Z, C₂H₆O, in a nucleophilic addition reaction using NaBH₄. All the hydrogen atoms in the NaBH₄ are the ³H isotope. NaBH₄ CH₃CHO → C₂H₆O compound Z Compound Z is then oxidised back to ethanal and water. C₂H₆O + [O] → CH₃CHO + H₂O Which statement about the final mixture of products is correct?

ABoth ethanal and water contain ³H atoms.
BEthanal is the only product containing ³H atoms.
CNeither ethanal nor water contain ³H atoms.
DWater is the only product containing ³H atoms.

✓ Correct answer

A: Both ethanal and water contain ³H atoms.

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About this question

Topic
Organic synthesis, A-Level Chemistry (syllabus 9701). Multiple choice, 1 mark.
Source
A-Level Chemistry, Feb/Mar 2021 Paper 1 Variant 2, question 27.

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