NEETChemistryBiomolecules
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): D-glucose gives Schiff's test and forms the hydrogen sulphite addition product with NaHSO₃ . Reason (R): The aldehyde group in D-glucose is not free as it is involved in hemiacetal formation to give a cyclic structure. In the light of the above statements, choose the most appropriate answer from th
Options
- ABoth (A) and (R) are correct and (R) is the correct explanation of (A)
- BBoth (A) and (R) are correct but (R) is not the correct explanation of (A)
- C(A) is correct but (R) is not correct
- D(A) is not correct but (R) is correct
Correct answer
D. (A) is not correct but (R) is correct
Step-by-step solution
Assertion (A) is incorrect because despite having an aldehyde group, D-glucose does not give Schiff's test and it does not form the hydrogen sulphite addition product with NaHSO₃ . Reason (R) is correct because the aldehyde group in D-glucose is not free. It undergoes intramolecular reaction with the -OH group at C-5 to form a cyclic hemiacetal structure, which explains the absence of certain characteristic reactions of free aldehydes. Therefore, (A) is not correct but (R) is correct. Answer: (A) is not correct but