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Chemistry · 2026 · 3 marks
CBSE 2026 · Region 1 · Set 3 · Q26
How do you explain the presence of following in open structure of glucose? (a) all the six carbon atoms are in a straight chain. (b) five -OH groups…
How do you explain the presence of following in open structure of glucose ?
(a)
all the six carbon atoms are in a straight chain.
(b)
five -OH groups which are attached to different carbon atoms.
(c)
an aldehyde group.
Marking-scheme solution
(a)
Glucose on reaction with HI forms n-hexane confirms straight chain of
six carbon atoms. /
(b)
Glucose on reaction with (CH3CO)2O forms pentaacetate as a stable
compound and confirms the presence of $\displaystyle 5$-OH group. /
(c)
Glucose on reaction with Br2 water gives Gluconic acid and confirms the
presence of aldehydic group. /
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CBSE Class 12 Chemistry past-paper question from the 2026 board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.