Which of the following cannot be explained by the open chain structure of glucose?
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → Glucose exists in two forms in nature; $α$ and $β$.
- Glucose reacts with hydroxylamine → can be explained by open-chain aldehyde group (forms oxime).
- Glucose undergoes oxidation with nitric acid → can be explained by aldehyde and –CH₂OH groups in open chain form (forms gluconic and glucaric acids).
- Glucose reacts with acetic anhydride to form pentaacetyl glucose → all –OH groups in open-chain form can be acetylated.
- Glucose exists in two forms in nature; α and β → cannot be explained by open-chain structure, because α and β forms are cyclic (pyranose) forms resulting from ring closure (hemiacetal formation).