Question:
Assertion (A): The pentaacetate of glucose does not react with \(H_2N-OH\).
Reason (R): It indicates the presence of free −CHO group in glucose.
Assertion (A): The pentaacetate of glucose does not react with \(H_2N-OH\).
Reason (R): It indicates the presence of free −CHO group in glucose.
Reason (R): It indicates the presence of free −CHO group in glucose.
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Hydroxylamine \(H_2N-OH\) reacts with a free aldehyde (\(-CHO\)) group to form an oxime. Whether glucose pentaacetate reacts with it tells us whether a free \(-CHO\) group is available.
Updated On: Jun 16, 2026
- Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
- Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
- Assertion (A) is true, but Reason (R) is false.
- Assertion (A) is false, but Reason (R) is true.
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The Correct Option is C
Solution and Explanation
Concept:
Hydroxylamine \(H_2N-OH\) reacts with a free aldehyde (\(-CHO\)) group to form an oxime. Whether glucose pentaacetate reacts with it tells us whether a free \(-CHO\) group is available.
Step 1:
Assertion: Glucose pentaacetate does not react with \(H_2N-OH\). This is TRUE. In the pentaacetate all five \(-OH\) groups are acetylated and the sugar is locked in the cyclic form, so no open chain \(-CHO\) group is available to react.
Step 2:
Reason: This indicates the PRESENCE of a free \(-CHO\) group. This is FALSE. The fact that it does not react actually indicates the ABSENCE of a free \(-CHO\) group in glucose pentaacetate.
Step 3:
So the Assertion is true but the Reason is false.
Answer: Option (3) — Assertion (A) is true, but Reason (R) is false.
Hydroxylamine \(H_2N-OH\) reacts with a free aldehyde (\(-CHO\)) group to form an oxime. Whether glucose pentaacetate reacts with it tells us whether a free \(-CHO\) group is available.
Step 1:
Assertion: Glucose pentaacetate does not react with \(H_2N-OH\). This is TRUE. In the pentaacetate all five \(-OH\) groups are acetylated and the sugar is locked in the cyclic form, so no open chain \(-CHO\) group is available to react.
Step 2:
Reason: This indicates the PRESENCE of a free \(-CHO\) group. This is FALSE. The fact that it does not react actually indicates the ABSENCE of a free \(-CHO\) group in glucose pentaacetate.
Step 3:
So the Assertion is true but the Reason is false.
Answer: Option (3) — Assertion (A) is true, but Reason (R) is false.
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