Question

Which of the following statements is not true about glucose?

• A. It is an aldose.
• B. On heating with HI it forms n-hexane.
• C. It exists in furanose form.
• D. It does not give Schiff's test.

Hint:

Schiff's reagent tests for aldehydes, and glucose, being an aldose, will give a positive result.

Answer 1

The Correct Option is A

The query requires identification of the false statement regarding glucose. The options are assessed as follows:

• Glucose is an aldose: This is accurate, as glucose possesses an aldehyde group on its initial carbon atom. This statement is true.
• Upon heating with HI, glucose yields n-hexane: This is a definitive reaction where the entirety of the glucose molecule is reduced to n-hexane when subjected to hydrogen iodide. Consequently, this statement is also true.
• It adopts the furanose form: Glucose characteristically forms a pyranose ring upon cyclization, rather than a furanose structure. Hence, this statement is not true for glucose.
• It does not react with Schiff's test: Glucose does not yield a positive Schiff's test. Although it contains an aldehyde group, it readily forms a stable cyclic hemiacetal, which generally does not react with Schiff's reagent. Therefore, this statement is true.

Based on the preceding evaluation, the incorrect statement concerning glucose is: It exists in furanose form.