Write the reactions of D-glucose which can't be explained by its open chain structure. How can cyclic structure of glucose explain these reactions?

Explanation

Chemical reactions of D-glucose which can't be explained by its open chain structure are
(i) Glucose does not give Schiff's test and does not produce hydrogensulphite addition product with `NaHSO_(3)`, despite having aldehyde group
(ii) The pentaacetate of glucose does not react with hydroxylamine. In actual, glucose exist in two different crystalline form `alpha` form and `beta` form. it was proposed that one of the OH groups may add to the `-CHO` group and form cyclic hemiacetal Cyclic structure exist in equilibrium with open structure and can be represented as

Due to formation of cyclic structures of glucose `CHO` group of glucose remains no longer free due to which they do not show above given reactions.